# Rider Area Distance fit theory... thoughts?



## tjc4golf (Mar 5, 2010)

I was just introduced to the concept of rider area distance (RAD) on Jeff Lenosky's YouTube channel. RAD is the length from bottom bracket to handlebar. It's the hypotnuse of the triangle created if you connected the stack and reach to form a triangle.

The RAD idea was first proposed by Lee Likes Bikes (LLB) who has proposed the formula: RAD = rider height * 4.47

Supposedly with MTBs getting longer RAD numbers are getting out of whack.

I'm 5"10" and ride a size M bike. The bike manufacturer's chart say 5'10" overlaps with L so you'd think M would be a little small. But my RAD is a 791mm and my bike measures 844.5mm from BB to bars.

Lenosky says he agrees with LLB for full suspension bikes but actually likes his hardtail shorter than what LLB's RAD suggests because of the way a hardtails suspension makes it longer whereas the full suspension bike's suspension makes it shorter. That would make my hardtail that's already too long even longer.

I was just curious to see what other people thought about this RAD concept and how their RAD and actual measurements compare.


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## Mark_BC (Sep 19, 2012)

I have a long torso in relation to my legs so I wonder if this captures it better


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## Varaxis (Mar 16, 2010)

Even if long enduro bikes had similar RAD, their long wheelbases would make techniques require more force to pull off. That's part of the benefit of the long wheelbase, to make the bike more numb to input forces, like a rock or other obstacle smashing into the wheel. When the bike feels calmer, you feel like you have room to go harder.

The bike is built to be optimized towards a certain kind of riding. Building around a # like RAD, HA, ETT, STA, or whatever has its own trade-offs. If I downsized because the RAD was too long, it'd probably compromise the seated position's comfort, perhaps leading to excess pressure on the hands and butt. Since the RAD is correct, I'd and the reach is familiar, I'd be left to blame something like the steep STA or maybe accuse modern geo as going the wrong direction since it makes choosing a bike with proper RAD in your size very hard.


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## tjc4golf (Mar 5, 2010)

Varaxis said:


> Even if long enduro bikes had similar RAD, their long wheelbases would make techniques require more force to pull off. That's part of the benefit of the long wheelbase, to make the bike more numb to input forces, like a rock or other obstacle smashing into the wheel. When the bike feels calmer, you feel like you have room to go harder.
> 
> The bike is built to be optimized towards a certain kind of riding. Building around a # like RAD, HA, ETT, STA, or whatever has its own trade-offs. If I downsized because the RAD was too long, it'd probably compromise the seated position's comfort, perhaps leading to excess pressure on the hands and butt. Since the RAD is correct, I'd and the reach is familiar, I'd be left to blame something like the steep STA or maybe accuse modern geo as going the wrong direction since it makes choosing a bike with proper RAD in your size very hard.


I think one of the points Lenosky makes is the recent fascination with long and slack, enduro-influenced geometry has made it harder to find bikes that fit in a traditional, well-rounded sense. Too much enduro-specialization sacrifices all-around performance.


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## CrozCountry (Mar 18, 2011)

Not necessarily. Bikes have longer reach, but stems are shorter too. 35-50mm stems are the norm, compared to 80-90mm a decade ago. And even longer before that. This ~40mm difference is in the ballpark of the difference in reach.

RAD is an approximation, reach + stack to the handlebars paint a more accurate picture. For example, on one of my bikes my the bar was too high, not RAD too long. Shorter stem would have the opposite effect of lowering the stem (but they both would have the same RAD effect).


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## emu26 (Jun 23, 2008)

I think this is way to serious a bike related topic to be in the OC. I'm now going to have to go off and check all of these dimensions to see where my latest build sits. Although completely different geo to my hardtail, I sized the frame so that I could keep seat clamp to centre of bar and bb to centre of seat clamp the same as my hardtail without the use of an offset post. I have achieved that and yet the two bikes assume completely different seated feels.I'll come back with more detail later.

Other than that, all I can say is all of my bikes have always been RAD to the MAX


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## Gumby_rider (Apr 18, 2017)

If I only ride downhill or jump then RAD is prob great but I don’t. Pedaling on bike with RAD fit sucks. My bike is RAD++.


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## jeremy3220 (Jul 5, 2017)

I think the height based formulas aren't accurate enough. There was a video Lee was in where he showed how to measure RAD directly and I found this much more useful because it accounts for everything (height, arm length, inseam, etc). At 6'5" my calculated RAD is way smaller than my actual RAD. I was surprised to find that my gigantic XXL Santa Cruz is about 1" below my RAD. Also, his bar width calculation says my max bar width would be 860mm!


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## MOJO K (Jan 26, 2007)

pages of this discussion


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## Rngspnr (Feb 15, 2016)

I've watched these videos and like everyone here got to thinking how does my current bike fit me? Well I did the ladder test and the RAD equations and my bike came up pretty much spot on. My bike felt like a great fit from the first day of building it. Now I think these equations are good for your average trail riding especially tech and tight switchback trails. Which are my typical trails, I find that for where I ride a wheelbase of less than 1200mm is the best. Now for fast flow trails I could see a longer wheelbase and reach being more advantageous.


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## chomxxo (Oct 15, 2008)

In reading both threads I see a consistent misunderstanding of what RAD is and how to measure it. I bought the book "Dialed" and it definitely explains this in detail.

That said, the book includes recommended reach measurements that are outdated. Reach is relative to the seat tube angle and older bikes at 72*, for instance, have shorter reach than a 75* STA new bike with longer reach. 

RAD is simply the distance between BB and the top-center line of the handlebars. Regardless of your bike design, it's supposed to be the same. RAAD, or the angle of your RAD, is adjustable considering whether you are a DH or XC rider, but RAD should be the same. 

In studying the book I shortened my stem to a stubby 35mm AND threw some backsweep in to get down to the shorter RAD I needed on a bike with 505mm reach. It feels great--the idea is that your bike is more maneuverable and you have some slack in your arms to handle terrain and cornering better. Too stretched out and you can't control the bike adequately.


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## b rock (Jan 5, 2017)

jeremy3220 said:


> I think the height based formulas aren't accurate enough. There was a video Lee was in where he showed how to measure RAD directly and I found this much more useful because it accounts for everything (height, arm length, inseam, etc). At 6'5" my calculated RAD is way smaller than my actual RAD. I was surprised to find that my gigantic XXL Santa Cruz is about 1" below my RAD. Also, his bar width calculation says my max bar width would be 860mm!


I suspected my bike was a bit long from how it felt at pump tracks and flat corners and stuff. So I did the on the bike check by paying super close attention to this part of the video of where the knuckles are supposed to be (behind the middle of the grips) and how to do your posture with the on the bike check, and confirmed that my knuckles were about 40 cm below the center of the grips: 




I think the on the bike check is the best way to go to see if your bike setup is too long vs all the measurements and multipliers, as you can't mess anything up except your posture. I used barstools with some plastic beneath the pedals to prevent damage. Once you are convinced by the on the bike check, and want to move forward, I found that measuring my height really carefully in cm made a difference for the next step, because I had rounded up my height in inches and stuck with that number for a long time, even though it wasn't quite right.

For me, the multiplier formula for RAD is a few mm too large vs the on the bike check, but there is "rider and bike calculator" available on his site if you sign up for a free month that agreed with the on the bike check pretty closely, and helps you pick out a stem and handlebar if you can use the handlebars that people have measured setbacks for (some good ones for me there). I swapped to a 30mm stem and 15mm rise handlebars and the bike feels easier to corner and hop, and it felt fine on a steep loose trail. But, I had waited until my stock handlebars and stem were 3 years old, and I wanted to replace them anyways for safety, since they had hit the dirt many times.

As far as the recommendations for bars over 800mm in width for people a few inches over 6', he answers this question a lot, and says that bigger number is just a max for people, and usually people go a little bit below the max, like with RAD. I went with 800mm instead of the ~830mm recommendation, even though 820mm bars exist, because I couldn't find a 30mm stem that was rated for more than 800mm bars.


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## One Pivot (Nov 20, 2009)

I think mtb "fit" is a scam. Bikes fit trails to a pretty large degree. 

Crazy low, slack bikes pop up around the time that flow trails get huge. Low bb's rip on flow trails. "Back country" used to be kind of popular, and a 14" bb was great for crawling over huge rocks on an unestablished trail. 

If OG nasty slow chunk trails get popular again, someone will "revolutionize" fit again and bikes will change. We'll all wonder how we ever rode LLS bikes.


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## BansheeRune (Nov 27, 2011)

One Pivot said:


> I think mtb "fit" is a scam. Bikes fit trails to a pretty large degree.
> 
> Crazy low, slack bikes pop up around the time that flow trails get huge. Low bb's rip on flow trails. "Back country" used to be kind of popular, and a 14" bb was great for crawling over huge rocks on an unestablished trail.
> 
> If OG nasty slow chunk trails get popular again, someone will "revolutionize" fit again and bikes will change. We'll all wonder how we ever rode LLS bikes.


Have to laugh at the whole thing...

Frankly, my slack, high BB bike with a stack that doesn't require slumping over to grip the bar does me dandy! I hate the hell out of having to call AAA to get a bicycle that high centered on a speed bump in front of the corner package store...


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## MtbrWNoMtn (Sep 10, 2020)

43yo noob recently began jumping and such, all very tame small stuff. Working on manuals and wheelies. 6'3" on XL Hardtail that was rad+ by the recent joy of biking video approach. I went with a shorter stem, bars with more back sweep, and moved some of the spacers around. Ended up slightly rad- and I am enjoying the change. No issue feeling cramped in cockpit pedaling and am able to generate noticeably more torque. Will I fiddle with it some more, yeah that's part of the fun, but count me as a rad fan.

On related note, did anyone notice how high Lee kept his seat when working the technical climbs in the video this week? I realize his understanding and ability is 1000x mine but that's not my approach to those sorts of things. Get that seat out of the way  I'm probably using 10x more energy while he's 10x more successful lol, but still, drop the dropper for more chi bud.

Joy of biking videos have been solid for me in my learning stages.


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## TylerVernon (Nov 10, 2019)

I like my enduro bikes with an ett of 600 and my trail and xc bikes at 640mm.


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## RS VR6 (Mar 29, 2007)

My RAD is about 80cm actually measuring myself. One bike is just about spot on...the other bike is about 1cm short. I measured my GF and she is about 78cm. The RAD on her bikes are both about 81cm.

The thing is that out of the four bikes in the garage...the one that has the longest reach...measured the shortest. All bikes have a 50mm stem. The Ripley V3 LS and Spesh Stumpjumper (411 and 413) both have fairly short reaches...but both have the longest RAD. The V1 Evil Following (feels like it fits me best) has a 419 reach and Banshee Spitfire V2 has a reach of 430. All bikes are mediums.

I'm also thinking about trimming my bar down from 760 to 740.


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## stripes (Sep 6, 2016)

I'm going to have the unpopular opinion about reading what you someone says in a fit that works for everyone. it doesn't fit everyone. Everyone is built differently.

If you're interested in getting fitted, go pay a reputable fitter for mountain bikes and get fitted for your bike. This way they can SEE you and how you move. Not just plug in random numbers from a formula online and this is your fit.

The RAD concept fit is a one-size fits all, and does not take into account any mobility issues you may have, weird things that go on with your body, nor does it take into account a seated bike position. I know, because I've done this with Lee before (had several in-person sessions with him, including the whole step ladder thing), and it still ended up not benefiting me. Lee's got a good idea, but it doesn't match a lot of the newer geos, so he suggests sizing down. I ended too crunched up, which did nothing to help my spine or hips. Don't assume that this is one-size that fits you. He looks for specific movements on the bike, but he doesn't watch the way your spine and hips behave on the bike even when you do this in person. Nor does every person my height want to run 740mm bars and a 40mm stem, ugh.

Full disclosure: I like Lee, and I think he's a fantastic skills teacher. He taught me how to pump, and helps me refine other things (I have another clinic with him in a couple weeks). But I did tell him he's not allowed to ever talk bike fit with me, so we agree to disagree on his RAD principle.


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## MOJO K (Jan 26, 2007)

stripes said:


> I'm going to have the unpopular opinion about reading what you someone says in a fit that works for everyone. it doesn't fit everyone. Everyone is built differently.


Fitting a bike is very much like trying on shoes. The size charts, construction, style, value, and reviews might all seem right but you don't really know anything until you slip 'em on, lace 'em up, and take a couple steps.


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## cookieMonster (Feb 23, 2004)

I’m tired of thinking about bike measurements, so I’m just gonna go ride my bike and see how it goes.


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## Impetus (Aug 10, 2014)

I’ve really come to the conclusion that RAD just doesn’t work for me.
I have a degree in biomechanics, and am a sports/ortho physical therapist, so I can follow the logic of what Lee says, but neither of my bikes are even in that same zip code as my calculated RAD.
I’m 5’9”, my measurement with the marker in hand on the wall is IIRC 735mm. Both my FS and my hardtail have a RAD of something in the low 800s! Neither has a long reach- the HT is a 450 reach, the FS is a 445. I’m running 50 and 55mm stems with 780 bars. To get my bike fit down to the suggested RAD, I’d be in my 5’5” wife’s bike, or I’d be running a 32mm stem with flat bars, and I’d be slamming my knees into the dropper lever.

I’ve done the ladder-test and the bars are juuust short of being comfortably in hand, I’m also really comfortable on both my bikes, so I don’t sweat it.


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## jeremy3220 (Jul 5, 2017)

Impetus said:


> I've really come to the conclusion that RAD just doesn't work for me.
> I have a degree in biomechanics, and am a sports/ortho physical therapist, so I can follow the logic of what Lee says, but neither of my bikes are even in that same zip code as my calculated RAD.
> I'm 5'9", my measurement with the marker in hand on the wall is IIRC 735mm. Both my FS and my hardtail have a RAD of something in the low 800s! Neither has a long reach- the HT is a 450 reach, the FS is a 445. I'm running 50 and 55mm stems with 780 bars. To get my bike fit down to the suggested RAD, I'd be in my 5'5" wife's bike, or I'd be running a 32mm stem with flat bars, and I'd be slamming my knees into the dropper lever.
> 
> I've done the ladder-test and the bars are juuust short of being comfortably in hand, I'm also really comfortable on both my bikes, so I don't sweat it.


Did you do the wall test with your legs straight? They didn't explain it in the video but once you get into your riding foot position, straighten your legs.


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## old_er (Dec 27, 2020)

Interesting the timeliness of this topic. I bought a new mtb back in January, a 2020 SC Tallboy C V4 size large. I was able to take it for a brief test ride and found it fit very well. Shortly after that I start seeing this topic of RAD on Joy of Bikes and a few others. I'm somewhat OCD and this sent me into analysis mode. I found my new bike was bigger than my RAD. I only had a couple of rides on it and starting thinking my re-entry to mtb after some years away was already flawed. I'm pretty anal about my fit and tried a shorter stem (40mm vs 50mm) which made my bike very twitchy. I decided to ignore this RAD stuff and just ride and find my skills are coming back, albeit slowly. I had the opportunity to ride a bike that was my RAD size, I hated the fit, it felt very cramped. I am 5'11" and have 33.5" inseam and a very big wingspan.

Just like all the other formula driven bike fits it doesn't work for everyone. I'm sure some of you read Greg LeMond's book back in the 80's and set their seat height to inseam*0.883. I know I did until my knees told me otherwise.


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## Impetus (Aug 10, 2014)

jeremy3220 said:


> Did you do the wall test with your legs straight? They didn't explain it in the video but once you get into your riding foot position, straighten your legs.


I did. I've watched most of JoBs videos, a bunch of LLBs, and even a few random YTers making videos about JoB.
Even Assuming I didn't straighten my knees, and stayed in the 'slight-crouch' attack standing position, it doesn't come close to account for the near 100mm discrepancy.
It's bizarre.


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## RS VR6 (Mar 29, 2007)

Impetus said:


> I've really come to the conclusion that RAD just doesn't work for me.
> I have a degree in biomechanics, and am a sports/ortho physical therapist, so I can follow the logic of what Lee says, but neither of my bikes are even in that same zip code as my calculated RAD.
> I'm 5'9", my measurement with the marker in hand on the wall is IIRC* 735mm*. Both my FS and my hardtail have a RAD of something in the low 800s! Neither has a long reach- the HT is a 450 reach, the FS is a 445. I'm running 50 and 55mm stems with 780 bars. To get my bike fit down to the suggested RAD, I'd be in my 5'5" wife's bike, or I'd be running a 32mm stem with flat bars, and I'd be slamming my knees into the dropper lever.
> 
> I've done the ladder-test and the bars are juuust short of being comfortably in hand, I'm also really comfortable on both my bikes, so I don't sweat it.


I'm 5'8" 30 inseam and my RAD measured ~80cm. Are your arms super long or legs super short??

My GF at 5'6" 30 inseam measured at ~78mm.

I had to measure myself a few times because I kept bending at my waist to see the mark.

All my bikes are mediums with 50mm stems. All of my bikes are fairly short in reach. The RAD on all four measure between 79 and 81cm. One measured exactly at 80cm.


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## Impetus (Aug 10, 2014)

RS VR6 said:


> I'm 5'8" 30 inseam and my RAD measured ~80cm. Are your arms super long or legs super short??
> 
> My GF at 5'6" 30 inseam measured at ~78mm.
> 
> ...


I dunno. I just measured it again. I've got on my Specialized Rime shoes, my feet are 320mm apart, as if standing on pedals. My shoulders are back and down, elbows extended, arms along my thigh, a marker in my fist. I make a dot on paper. 742mm.

¯\_(ツ)_/¯


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## old_er (Dec 27, 2020)

RS VR6 said:


> I'm 5'8" 30 inseam and my RAD measured ~80cm. Are your arms super long or legs super short?😁
> 
> My GF at 5'6" 30 inseam measured at ~78mm.
> 
> ...


I was just reading yours and your girlfriends RADs. I am 5'11" with 33.5" inseam and 73.5" wingspan. My calculated RAD is 80cm and my actual body RAD is 78cm. That would put me on the same bike size as you and your GF.


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## stripes (Sep 6, 2016)

old_er said:


> I was just reading yours and your girlfriends RADs. I am 5'11" with 33.5" inseam and 73.5" wingspan. My calculated RAD is 80cm and my actual body RAD is 78cm. That would put me on the same bike size as your and you GF.


The point of the RAD measurement is to get people to size down one or two sizes, so you're not wrong.

I rode an XS at 5'5" based on that. Too twitchy, and I was way too crunched up. Now i get way ledgy trails were particularly nerve wracking.

Two years ago got on a medium and my riding has improved significantly. Body feels much better, and my bike handling is much better too because the twitchiness is gone.


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## BansheeRune (Nov 27, 2011)

stripes said:


> The point of the RAD measurement is to get people to size down one or two sizes, so you're not wrong.
> 
> I rode an XS at 5'5" based on that. Too twitchy, and I was way too crunched up. Now i get way ledgy trails were particularly nerve wracking.
> 
> Two years ago got on a medium and my riding has improved significantly. Body feels much better, and my bike handling is much better too because the twitchiness is gone.


Any time one can be on a bike that is relaxed in terms of fit as opposed to knees in front of the bar or reaching to the next door neighbors front door, the ride experience will be superior.
Now it would get down to what caster angle is comfortable for you and forget everyone else, not to mention STA and how that affects your spin and power production range.
Remember, you are the one writing the check, you are the one tasked with riding it. Fitment should be a pleasure, not a chore.


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## RS VR6 (Mar 29, 2007)

old_er said:


> I was just reading yours and your girlfriends RADs. I am 5'11" with 33.5" inseam and 73.5" wingspan. My calculated RAD is 80cm and my actual body RAD is 78cm. That would put me on the same bike size as you and your GF.


The RAD measurement is nothing more than the measurement from the crank spindle to the virtual center of your grips. It for the full range of motion. You can get the same RAD on a medium and a large. Most bikes are designed around a 30 to 50mm stem. I can get a small and use a longer stem...or a medium and use a shorter one. Its a consistent number that can me moved from bike to bike depending on the handling characteristics you're looking for. Your fit will be similar across multiple bikes. He's not a bike company trying to sell you a bike. He's just basing it on his experiences as a MTB coach.

People are going to have their preferences regardless of what anyone says. Do what makes you happy.


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## old_er (Dec 27, 2020)

RS VR6 said:


> The RAD measurement is nothing more than the measurement from the crank spindle to the virtual center of your grips. It for the full range of motion. You can get the same RAD on a medium and a large. Most bikes are designed around a 30 to 50mm stem. I can get a small and use a longer stem...or a medium and use a shorter one. Its a consistent number that can me moved from bike to bike depending on the handling characteristics you're looking for. Your fit will be similar across multiple bikes. He's not a bike company trying to sell you a bike. He's just basing it on his experiences as a MTB coach.
> 
> People are going to have their preferences regardless of what anyone says. Do what makes you happy.


I understand the concept. I can't get my size large Tallboy set to a 78cm RAD but I have tried another bike that was a medium that measured 78cm RAD. When I set my seat height for my legs the bar drop was uncomfortable and to get the bar height up it would have gone over RAD. I rode the bike and found my legs hitting the bars on standing pedaling and I was leaned over the bars quite a bit.

I'm not saying this fit doesn't work for some but it is not a universal thing. My Tallboy measures 84cm RAD and gives me the room I need for my legs and arms. The cool thing is the human body is remarkably adaptable. The best thing is a comfortable bike is one you like to ride. That makes me happy.


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## b rock (Jan 5, 2017)

I think the body measurements, aside from your height, are too easy to mess up. Is the pen level, are your hands the right distance apart, are you knees straight, are your shoulders packed? Etc etc. Just do the step ladder test with your bike if you feel like it is hard to pump, jump, turn, or your back hurts after a few hours riding. If you are mostly an XC, non technical rider, this stuff doesn’t apply as critically, same if you are a more passive rider, looking to sled down the hill.


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## stripes (Sep 6, 2016)

b rock said:


> I think the body measurements, aside from your height, are too easy to mess up. Is the pen level, are your hands the right distance apart, are you knees straight, are your shoulders packed? Etc etc. Just do the step ladder test with your bike if you feel like it is hard to pump, jump, turn, or your back hurts after a few hours riding. If you are mostly an XC, non technical rider, this stuff doesn't apply as critically, same if you are a more passive rider, looking to sled down the hill.


The RAD does not take into account seated pedaling. Enduro and XC both do it, and for me, that's where it kills me. My RAD is a lot smaller than where I'm comfortable uphill or seated pedaling.

It also doesn't work for me because it forces me into a much more cramped position that my spine seriously objects to, even on the pump track.

I wouldn't say DH riders are necessarily passive either-RAD is a fine that works for some folks, but it's not for everyone.


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## old_er (Dec 27, 2020)

stripes said:


> The RAD does not take into account seated pedaling. Enduro and XC both do it, and for me, that's where it kills me. My RAD is a lot smaller than where I'm comfortable uphill or seated pedaling.
> 
> It also doesn't work for me because it forces me into a much more cramped position that my spine seriously objects to, even on the pump track.
> 
> I wouldn't say DH riders are necessarily passive either-RAD is a fine that works for some folks, but it's not for everyone.


Your analysis is spot on.
I'm in the northeast (NY/NJ area) so undulating and technical (rocks and roots) are everywhere. Not a lot of long downhill or uphill but for some reason there seems to be more uphill than downhill.


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## stripes (Sep 6, 2016)

old_er said:


> Your analysis is spot on.
> I'm in the northeast (NY/NJ area) so undulating and technical (rocks and roots) are everywhere. Not a lot of long downhill or uphill but for some reason there seems to be more uphill than downhill.


It's crazy how many people take this as gospel. I've seen people ride with 30 and 50mm bars ridden upside down to meet their RAD, rather than fit the bike to them, they force themselves into a RAD. Lee thought of this back 5 years ago or so, where bike geometries were so different than they are now. It hasn't evolved at all, and as the bike change, it makes it really difficult for this to apply to everyone over the years. Even you and I, both riding different types (more park and DH for me, more XC for you), it doesn't work for us. A few of my other friends have had to readjust from it too--neck and shoulder issues from what I remember. Not worth getting hurt to match some numbers on the internet so I squish into them.


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## MtbrWNoMtn (Sep 10, 2020)

Seems to me that as bikes getting longer, RAD is more important if you are trying to do the things that require you to have leverage over the front end. If you are not able to generate a ton of torque on a BMX, that's fine only a small amount of torque is needed to pull a manual. Modern geometry enduro with 180mm travel bike, If you want to have more control over the front end, more ability to "PULL UP", manual, wheelie, drop off ledges with control at slower speeds. Having that leverage makes it require less energy to accomplish. If you're bombing smooth downhills holding on for dear life, that's different.

Also the "it doesn't feel right" argument is sometimes flawed imo. We get accustomed to a bike and then that feels right, change geometry, stem length, spacers, where the levers are... feel is impacted. Decide you like it for one reason or another it will feel right over time. Decide you don't like it for one reason or another and "it doesn't feel right".

Pick up something with some weight off the floor close to your feet. Now try to do it with it gradually further and further away from your feet. Leverage decreases as that distance increases plain and simple. If you have enough leverage to pop up tough climbs, manual without exerting everything you can, yank a J hop you are proud of, u good. Riding a bike giving you enjoyment, NICE!


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## chomxxo (Oct 15, 2008)

Agree, feel means almost nothing, not buying the "RAD is too short for my spine and climbing." I've shortened my RAD from what thought it should be before to the measured distance of about 30mm closer to me, and the bike climbs great. Now I can corner more confidently and lift the bike more easily. With steeper seat tube angles (or virtual STA by sliding your rails forward), it's not necessary to weight the front end as much and you can climb in a position that handles better.

Lee rails about super-long reach these days, but I wish he'd also mention that reach used to be much too short. There's nothing good about a bike with a 90mm-120mm stem--something was wrong with bikes a few years back, and now they're much better fits.


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## b rock (Jan 5, 2017)

stripes said:


> The RAD does not take into account seated pedaling. Enduro and XC both do it, and for me, that's where it kills me. My RAD is a lot smaller than where I'm comfortable uphill or seated pedaling.
> 
> It also doesn't work for me because it forces me into a much more cramped position that my spine seriously objects to, even on the pump track.
> 
> I wouldn't say DH riders are necessarily passive either-RAD is a fine that works for some folks, but it's not for everyone.


Yeah, there are too many variables to make one formula work every time, and this one isn't focussed on seated pedaling.

I think the step ladder test is a good starting point for people who don't feel quite right on their bike, since a professional fit might not work out either, and can be expensive, but perhaps better informed.

The sled comment is not aimed at DH riders, who can be very active and mobile on their bikes, but was more of a lazy way to say, sizing down won't work for people who feel really tied to the longest wheelbase they can work. Personally, I haven't sized down on my modern bike, just tweaked my reach and stack down a bit, and widened my handlebars at the same time, which can counteract the steering effect if simultaneously going to a shorter stem.


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## shakazulu12 (Jul 14, 2015)

Curiosity got the best of me. I bought his guide and will play around with it later. Though I suspect it's going to be tough with my build. I'm 5'11" with a 6'6" wingspan and I suspect no calculator out there is going to work with that.


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## old_er (Dec 27, 2020)

shakazulu12 said:


> Curiosity got the best of me. I bought his guide and will play around with it later. Though I suspect it's going to be tough with my build. I'm 5'11" with a 6'6" wingspan and I suspect no calculator out there is going to work with that.


Wow, that is a wingspan! Are your legs long as well? That would be an interesting fit.


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## shakazulu12 (Jul 14, 2015)

old_er said:


> Wow, that is a wingspan! Are your legs long as well? That would be an interesting fit.


Inseam is right at 34. Not sure if that's long or not as I haven't been riding that long. Arms sure helped when I was a basketball player though


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## old_er (Dec 27, 2020)

shakazulu12 said:


> Inseam is right at 34. Not sure if that's long or not as I haven't been riding that long. Arms sure helped when I was a basketball player though


I'd say you have relatively long legs too. What are you riding now?


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## stripes (Sep 6, 2016)

chomxxo said:


> Agree, feel means almost nothing, not buying the "RAD is too short for my spine and climbing." I've shortened my RAD from what thought it should be before to the measured distance of about 30mm closer to me, and the bike climbs great. Now I can corner more confidently and lift the bike more easily. With steeper seat tube angles (or virtual STA by sliding your rails forward), it's not necessary to weight the front end as much and you can climb in a position that handles better.
> 
> Lee rails about super-long reach these days, but I wish he'd also mention that reach used to be much too short. There's nothing good about a bike with a 90mm-120mm stem--something was wrong with bikes a few years back, and now they're much better fits.


Sure, you can have that conversation with my PT on how bad a cramped position is for my spine and hips.  I also can't ride bikes with too steep of a SA either.. same problem. The RAD works if you're gonna ride out of the saddle the whole time, but that's not realistic for 95% of the people out there.

Lee has always been railing about super long reach for years. It's not just these days, but for a long time. Back when he created his fit, people were regularly riding on 60-80mm stems, so he created this fit system to compensate for that, and back then it made a lot of sense, and it worked fine for me up until I got my first long/low/slack HA/steep SA bike in 2017. His fit was also good before the steeper SA too. Now we're pretty much on 35-50mm stems for the most part, and most bikes have their designs compensate for that.

Lee and I have an agreement: I can take skills lessons with him, and I think he's really a great instructor. But he cannot at all discuss bike fit with me. We agree to disagree on fit, and I respect him for that.


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## shakazulu12 (Jul 14, 2015)

old_er said:


> I'd say you have relatively long legs too. What are you riding now?


I'm riding a Large Megatower. So far, I really have no complaints and haven't gotten to messing with cockpit other than rotating the bars and moving the levers etc. But I also kinda wonder "what if?" and like to geek out on stuff sometimes. I'm treating it as an experiment that may or may not pencil out in performance, but I'll better understand my interaction with the bike.


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## stripes (Sep 6, 2016)

b rock said:


> Yeah, there are too many variables to make one formula work every time, and this one isn't focussed on seated pedaling.
> 
> I think the step ladder test is a good starting point for people who don't feel quite right on their bike, since a professional fit might not work out either, and can be expensive, but perhaps better informed.
> 
> The sled comment is not aimed at DH riders, who can be very active and mobile on their bikes, but was more of a lazy way to say, sizing down won't work for people who feel really tied to the longest wheelbase they can work. Personally, I haven't sized down on my modern bike, just tweaked my reach and stack down a bit, and widened my handlebars at the same time, which can counteract the steering effect if simultaneously going to a shorter stem.


I would agree not all pro fits are equal. There are some really crappy fitters out there too, which is why you have to find a reputable one in your area and if you can afford it. That's the hard part right? So yeah, then RAD does make a decent starting point.

The problem is people don't take RAD as a guideline--which is what they should do. Because because everyone references it, they think it's the Word, and never question.

There are other people who are other outliers: based on this formula, how would someone who's under 5' be able to fit? You'd want them on a kid's bike? What about the super tall people out there who are 6'4" and higher? And other folks with mobility issues...


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## jeremy3220 (Jul 5, 2017)

I think the main issue is in how it's measured. The height guideline is way too general. You need to measure RAD more directly. The wall method seems like it should be pretty accurate. I'm not sure how people are ending up feeling so cramped or running their bars upside down. I'm on a 76° STA bike with the seat slid forward and still feel very comfortable running a bit RAD-. Now if I went by the height calculator it would be a totally different story.


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## Gumby_rider (Apr 18, 2017)

Isn’t the internet great. How else people would have a chance to debate about a fit theory?

Watching the little kids with no upper body strength doing amazing on bikes that some might consider are too big for their size and weight almost half of their body weight pretty much convinced me that if the bike feels good then just ride it unless you get paid to ride then do what sponsors tell you. 

Personally I can’t imagine to be able to do anything well if it doesn’t feel good.


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## old_er (Dec 27, 2020)

Gumby_rider said:


> Personally I can't imagine to be able to do anything well if it doesn't feel good.


There are plenty of road bikers that go against that mantra. Zero spacers for the proper look and 8 cm drop from saddle to bars.


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## chomxxo (Oct 15, 2008)

I've never seen a rad kid with a RAD+ fit. The wheel size and weight might be proportionally larger, but their bikes are generally better fit than ours.

This stuff is hardly conjecture, and Lee has good reasons for saying that RAD- is fine, but RAD+ is dangerous.

I think you're trying to muddy the waters but you're just incorrect.



Gumby_rider said:


> Isn't the internet great. How else people would have a chance to debate about a fit theory?
> 
> Watching the little kids with no upper body strength doing amazing on bikes that some might consider are too big for their size and weight almost half of their body weight pretty much convinced me that if the bike feels good then just ride it unless you get paid to ride then do what sponsors tell you.
> 
> Personally I can't imagine to be able to do anything well if it doesn't feel good.


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## stripes (Sep 6, 2016)

chomxxo said:


> View attachment 1929197
> 
> 
> I've never seen a rad kid with a RAD+ fit. The wheel size and weight might be proportionally larger, but their bikes are generally better fit than ours.
> ...


Are you saying strictly for children or adults or both?

I ride RAD+, assuming this means greater than your RAD number. Doesn't appear to be dangerous.


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## old_er (Dec 27, 2020)

chomxxo said:


> View attachment 1929197
> 
> 
> I've never seen a rad kid with a RAD+ fit. The wheel size and weight might be proportionally larger, but their bikes are generally better fit than ours.
> ...


A typical BMX bike has a head tube angle around 74 to 76°, does Lee's RAD formula work in that realm? Most mountain bikes never had head tube angles steeper than 71° typically.
Kids tend to ride what they have, I know I did. Back the BMX craze of the mid 70's I wanted a BMX bike my parents said you already have a bike. I did what most kids did, scavenge and save and made my banana seat Huffy into a BMXer. I could wheelie for miles.


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## jeremy3220 (Jul 5, 2017)

old_er said:


> A typical BMX bike has a head tube angle around 74 to 76°, does Lee's RAD formula work in that realm? Most mountain bikes never had head tube angles steeper than 71° typically.


You definitely want your bmx to fit smaller than your trail bike. BMX is the extreme end of low stability and high maneuverability. I'm 6'5" and came from BMX, when I was shopping for my first mtb I thought a medium with 430mm reach felt fine. The shop had to talk me into an XL. Lee is a great mtb coach but I wouldn't trust him for bmx sizing.

I will say with those steep HTA's and tall bars, BMX bikes aren't as far off in fit as the wheelbase would suggest.


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## RS VR6 (Mar 29, 2007)

old_er said:


> There are plenty of road bikers that go against that mantra. Zero spacers for the proper look and 8 cm drop from saddle to bars.


When it comes to road bike fits...some fit for aero and output...some fit for comfort. If you're racing crits...you don't want that upright position. You're sacrificing power by sitting bolt upright.

The thing with the human body is that it can adapt...even to an extremely poor fit. I've done enough social rides too see a lot of poor fits. Friend of mine was one of them. He kept saying that it feels "comfortable"...it was comfortable until it injured his knees. I've also seen mountain bikers with the saddle pushed so far forward that their rear is hanging off the back of the saddle as they bounce along spinning at 120rpm. Some people don't know they have a bad fit until someone tells them they do...that or wait for an injury.

One of the early sales I did when I worked in a bike shop was a 56cm road bike to a 5'3" person. I asked if they are sure that they want that size. I also asked the manger if I should sell them that bike. He said I asked all the right questions and if that person insisted that they wanted that size...there is no problem selling them what they want. That person put the money down and bought the bike. Never seen them again. I'm 5'8"...my road bike is a 54cm...some other manufacturers I would ride a 52cm. Sizing a road bike isn't as ambiguous as a mountain bike.


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## old_er (Dec 27, 2020)

RS VR6 said:


> When it comes to road bike fits...some fit for aero and output...some fit for comfort. If you're racing crits...you don't want that upright position. You're sacrificing power by sitting bolt upright.
> 
> The thing with the human body is that it can adapt...even to an extremely poor fit. I've done enough social rides too see a lot of poor fits. Friend of mine was one of them. He kept saying that it feels "comfortable"...it was comfortable until it injured his knees. I've also seen mountain bikers with the saddle pushed so far forward that their rear is hanging off the back of the saddle as they bounce along spinning at 120rpm. Some people don't know they have a bad fit until someone tells them they do...that or wait for an injury.
> 
> One of the early sales I did when I worked in a bike shop was a 56cm road bike to a 5'3" person. I asked if they are sure that they want that size. I also asked the manger if I should sell them that bike. He said I asked all the right questions and if that person insisted that they wanted that size...there is no problem selling them what they want. That person put the money down and bought the bike. Never seen them again. I'm 5'8"...my road bike is a 54cm...some other manufacturers I would ride a 52cm. Sizing a road bike isn't as ambiguous as a mountain bike.


My comment about roadies was sarcastic humor. I realize bikes are fit particular ways for particular purposes. I road raced back in the early 80's, just club level stuff but bike fit became somewhat of an obsession. I bought Greg Lemond's book back in 87 and used the fit formulas he used from Cyrille Guimard. I forced myself to try to use that method for a while, what I realized is I didn't want to ride as much because the bike was no longer comfortable to ride.

A friend of mine is a road mileage junkie sometimes putting in 200+ miles on a weekend. His bike fit gave him thousands of pain free miles. He wanted to get to the next level and went to a "pro" fitter. After that Charlie wound up with neck and and hand pain that took him off the bike for a few months. Each bike fitter applies a theory but until they can step inside someones body they can't feel what is going on. I'm 55 so I am speaking from a little bit of life experience.


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## Riled (May 1, 2012)

The premise of RAD is based on getting the bike just short enough so you have better leverage to manual, row, pump, etc. If your riding style doesn’t use those things a lot, RAD isn’t going to benefit you as much. It does potentially sacrifice some stability by putting you on a shorter wheelbase.


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## RS VR6 (Mar 29, 2007)

old_er said:


> My comment about roadies was sarcastic humor. I realize bikes are fit particular ways for particular purposes. I road raced back in the early 80's, just club level stuff but bike fit became somewhat of an obsession. I bought Greg Lemond's book back in 87 and used the fit formulas he used from Cyrille Guimard. I forced myself to try to use that method for a while, what I realized is I didn't want to ride as much because the bike was no longer comfortable to ride.
> 
> A friend of mine is a road mileage junkie sometimes putting in 200+ miles on a weekend. His bike fit gave him thousands of pain free miles. He wanted to get to the next level and went to a "pro" fitter. After that Charlie wound up with neck and and hand pain that took him off the bike for a few months. Each bike fitter applies a theory but until they can step inside someones body they can't feel what is going on. I'm 55 so I am speaking from a little bit of life experience.


I didn't go get a fit on my road bike till I started feeling pain. I went full roadie and was doing about 80 to 100 miles a week. It was in my left lower back and the pain would shoot down my left leg. The ride the weekend after the fit was like a revelation. I was riding and climbing with more power and endurance. My saddle turned out was too low and too far back. He also switched me to a longer and lower stem. Moving me forward also let me ride in a lower more aggressive position. I asked about the lower bar position and comfort. He says as long as can ride without discomfort...I'm ok. I've used that same saddle position on all my mountain bikes. It been about 10 years now. No leg or lower back pain. I did move the bar on my road bike up since the fit though. I went from a -17 to a -8 rise stem. I don't ride the road bike like I used to.


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## Varaxis (Mar 16, 2010)

I see it as a matter of specificity training.

The old-school MTB position, especially with XC-style bikes, mimicked roadie positions. It's a common custom for riders to transfer their fit from one bike to the other. This allowed mtbers to take advantage of road training and the comfort/fit associated with it.

The new school bikes changed things. Longer WB and steeper STA allows them to ride _mountains_ better, both down and up. It's a different position that requires time to become more efficient at it, not too unlike how a TT or triathlon racer has to train in their own unique position to optimize their efficiency rather than train on a regular road bike. Their bikes offer an advantage that's worth the change.

These RAD guys enjoy BMX/pump-track riding and want to transfer it to MTB as much as possible. I suppose they're trying to appeal to riders who want to be "rad" too, getting these kind of skills. It's like they want to be reliant on these skills, rather than be reliant on modern bike geo. I understand the logic, that the skill can be transferred to a wide variety of bikes and are impressive to watch. Being overly reliant on modern geo makes you unwilling to ride lesser bikes.

These guys are like saying, "the closer the bike row movement is to a deadlift, the better." I argue that the long wheelbase makes the modern bikes difficult to use these techniques on, not the reach or whatever. 430mm reach with a 1250mm WB bike is a lot different than the same reach with a bike with 100mm shorter WB. Lee is 174cm (5' 8.5") and he's deciding between small and medium bikes. The difference between them is like 25mm reach and 25mm WB, so I bet they'll notice an improvement in kung-fu, but I worry about the fit of the small. Banging knees against the shift/dropper levers when pedaling doesn't sound like a fun time. I argue that they'd like a short WB with modern reach better, like a Forbidden Druid, Canfield Tilt, GG Trail Pistol, etc.

IMO, forcing the BMX handling feel (short WB) results in bikes like the Kona Honzo (OG, not ESD) and Canyon Stoic. They're like big BMX/DJ bikes or maybe like a slopestyle bike. The '21 Spec Status is probably their kind of bike (they might even like the old-school pedaling characteristic). It's akin to how forcing road bike fit resulted in the old XC bikes. What they refer to new/modern bikes are those that are more optimized for mountain-like terrain, which has been developed due to enduro racing. No surprise that they don't need all the features that make mountainous riding easier, based on where they show their riding footage.


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## RS VR6 (Mar 29, 2007)

Varaxis said:


> These guys are like saying, "the closer it is to a deadlift, the better." I argue that the long wheelbase makes the modern bikes difficult to use these techniques on, not the reach or whatever. 430mm reach with a 1250mm WB bike is a lot different than the same reach with a bike with 100mm shorter WB. Lee is 174cm (5' 8.5") and he's deciding between small and medium bikes. I worry about the fit of the small... banging knees against the levers when pedaling doesn't sound like a fun time.


I wonder what size Stumpjumper he rides. I can't tell of its a small or medium. He's got a tiny slammed stem on there. From some of the videos I've seen...I can see why he likes that deadlift position. Alex from JOB is building up a small and medium bike to see which one he prefers.

I watched a few of his videos trying to see how he came up with his RAD fit. From a few of the videos...I can see why he likes that "deadlift" position.

I put a 40mm stem on my GF's bike ( Medium Ibis Ripley V3 LS)...from a 50mm. I don't know if its in her head...but she's telling me that she likes the shorter stem more.


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## Riled (May 1, 2012)

The premise of RAD is based on getting the bike just short enough so you have better leverage to manual, row, pump, etc. If your riding style doesn’t use those things a lot, RAD isn’t going to benefit you as much. It does potentially sacrifice some stability by putting you on a shorter wheelbase.


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## stripes (Sep 6, 2016)

Riled said:


> The premise of RAD is based on getting the bike just short enough so you have better leverage to manual, row, pump, etc. If your riding style doesn't use those things a lot, RAD isn't going to benefit you as much. It does potentially sacrifice some stability by putting you on a shorter wheelbase.


So basically to turn your trail bike into a dirt jumper. Which makes total sense since Lee does 95% of his riding at Valmont.


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## jeremy3220 (Jul 5, 2017)

stripes said:


> So basically to turn your trail bike into a dirt jumper. Which makes total sense since Lee does 95% of his riding at Valmont.


Not in my experience. Based on the wall method my trail bike is RAD- and in no way shape or form does it fit small or cramped. The seated position with a 76° STA is quite spacious. I think his main goal is to prevent people from riding overly large bikes (hip angle too open). The problem is he has multiple methods of calculating RAD and some are definitely not useful (like estimating based on height).


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## old_er (Dec 27, 2020)

jeremy3220 said:


> Not in my experience. Based on the wall method my trail bike is RAD- and in no way shape or form does it fit small or cramped. The seated position with a 76° STA is quite spacious. I think his main goal is to prevent people from riding overly large bikes (hip angle too open). The problem is he has multiple methods of calculating RAD and some are definitely not useful (like estimating based on height).


I still can't get RAD thing out of my head. I understand what Lee is getting at but fit always has exceptions.
His body RAD measurement needs to be more consistent and precise. For sh*ts and giggles I took a wood dowel about the diameter of a handlebar and drilled a hole in the end to fit a pencil. I took my RAD measurement from the posture Lee suggests in JOB video. With this method my RAD cam out to 83cm versus 78cm with the marker against the wall.


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## jeremy3220 (Jul 5, 2017)

old_er said:


> I still can't get RAD thing out of my head. I understand what Lee is getting at but fit always has exceptions.
> His body RAD measurement needs to be more consistent and precise. For sh*ts and giggles I took a wood dowel about the diameter of a handlebar and drilled a hole in the end to fit a pencil. I took my RAD measurement from the posture Lee suggests in JOB video. With this method my RAD cam out to 83cm versus 78cm with the marker against the wall.
> View attachment 1929269


The exception would be people with long arms since the longer your arms for a given height, the shorter your wall measured RAD would be. It's not perfect. Maybe do the wall measurement then add 1/2 your ape index?

I kinda think hip angle would be a better metric, except it depends on riders maintaining a consistent position on the bike. If your bike is uncomfortably small that's an obvious indicator that it's too small regardless of fit metrics. However, it's harder for riders to know if their bike is larger than optimal (too stretched to generate power).


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## old_er (Dec 27, 2020)

jeremy3220 said:


> The exception would be people with long arms since the longer your arms for a given height, the shorter your wall measured RAD would be. It's not perfect. Maybe do the wall measurement then add 1/2 your ape index?
> 
> I kinda think hip angle would be a better metric, except it depends on riders maintaining a consistent position on the bike. If your bike is uncomfortably small that's an obvious indicator that it's too small regardless of fit metrics. However, it's harder for riders to know if their bike is larger than optimal (too stretched to generate power).


You are hitting the crucial point here is that there are so many variables a formula based fit cannot account for. At least one thing Lee has done is get us to think more about how we choose a bike even if we don't agree.


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## Gumby_rider (Apr 18, 2017)

I don't see how. Unless the bike is ridiculous large for the person's size, the proper techniques require only a tiny bit of force from the front. One can easily do any of those with RAD- to RAD++.



Riled said:


> The premise of RAD is based on getting the bike just short enough so you have better leverage to manual, row, pump, etc. If your riding style doesn't use those things a lot, RAD isn't going to benefit you as much. It does potentially sacrifice some stability by putting you on a shorter wheelbase.


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## Riled (May 1, 2012)

Gumby_rider said:


> I don't see how. Unless the bike is ridiculous large for the person's size, the proper techniques require only a tiny bit of force from the front. One can easily do any of those with RAD- to RAD++.


I agree with you, but that is what the premise of RAD appears to be when I watch the videos.

I can see that there is some minor difference in leverage depending on how big a bike is on you, but in practice I honestly don't know how big or noticeable it would be. I'm starting to think RAD is just a downstream way to measure wheelbase vs. rider weight and upper body strength. The wheelbase is ultimately the length of lever you're trying to lift, and the bike size vs. height just shifts the point you're lifting it from a few mm's. Whatever the point you're lifting the wheelbase lever from, you're using your weight shift and strength (row) to accomplish it. That's another reason I think RAD is victim to variables that a lot of people aren't talking about.


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## MtbrWNoMtn (Sep 10, 2020)

I find the arguments of the rad naysayers club bizarre.


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## Gumby_rider (Apr 18, 2017)

The naysayers said that RAD is uncomfortable for them. What's so bizarre about that? You questioning how comfortable others should be on THEIR bikes riding the types of trails they ride, now that's bizarre to me. This is after all recreational riding.



MtbrWNoMtn said:


> I find the arguments of the rad naysayers club bizarre.


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## MtbrWNoMtn (Sep 10, 2020)

Gumby_rider said:


> The naysayers said that RAD is uncomfortable for them. What's so bizarre about that? You questioning how comfortable others should be on THEIR bikes riding the types of trails they ride, now that's bizarre to me. This is after all recreational riding.


I specifically did the opposite of that. +1 for bizzario reply.


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## stripes (Sep 6, 2016)

MtbrWNoMtn said:


> I find the arguments of the rad naysayers club bizarre.


Because we all aren't built the same? Not everyone fits in a cookie cutter system.


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## MtbrWNoMtn (Sep 10, 2020)

stripes said:


> Because we all aren't built the same? Not everyone fits in a cookie cutter system.


I understand we are not all built the same. I can't speak for Mr. RipRow, but I suspect he has noticed that we are not all built the same. Do you believe RAD to be a cookie cutter system?

You're making my point for me.


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## stripes (Sep 6, 2016)

MtbrWNoMtn said:


> I understand we are not all built the same. I can't speak for Mr. RipRow, but I suspect he has noticed that we are not all built the same. Do you believe RAD to be a cookie cutter system?
> 
> You're making my point for me.


If you want, ask him. He loves to talk about it.

What is your point then? Your original post was a bit vague.


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## chomxxo (Oct 15, 2008)

Varaxis said:


> I see it as a matter of specificity training.
> 
> The old-school MTB position, especially with XC-style bikes, mimicked roadie positions. It's a common custom for riders to transfer their fit from one bike to the other. This allowed mtbers to take advantage of road training and the comfort/fit associated with it.
> 
> ...


One of the most insightful posts so far. Let me try to reconcile new geometry with Lee's great system but retro-grouch attitude. Here's my measurements:

6'4" tall, 6'7" wingspan, 37" true inseam. Tallboy 3 size XXL (505mm reach). When I discovered RAD I shortened the stem from 55 to 35mm and also employed some backsweep into the Enve M9 bars (cut to 770mm).

It might not sound like it, but I'm strictly an XC racer and my bike build is 23lbs. I'd recently gotten a pro bike fit to shorten my saddle height and crank length, but I realized something was still missing on the front end. It still felt like I was diving into corners and I couldn't lift the front end as well as I felt I should be able to.

I'd say, to reconcile old and new, you need a bike, regardless of discipline, with as short a stem as possible. A stem is a useless appendage. RAD was a novel concept for me to discover. As a stretched out XC racer I first discovered the need to replace long stems with long reach, but for years I never realized I could get better handling from shortening my stance.

A bike with maximum reach, minimum stem, but still fit to RAD is "magical" as Lee would say. To accommodate everyone there has to be a new default stem length on new frames of about 60mm, but I think we're there now, even with the best XC race bikes, so I don't see a problem.

For more magic, new bikes with steep STAs can avoid the climbing-dedicated pitfalls of old bikes (slammed banana  length stems paired with setback posts). You can have a more upright, better-handling stance and still climb as well or better.

Sent from my iPhone using Tapatalk


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## old_er (Dec 27, 2020)

chomxxo said:


> One of the most insightful posts so far. Let me try to reconcile new geometry with Lee's great system but retro-grouch attitude. Here's my measurements:
> 
> 6'4" tall, 6'7" wingspan, 37" true inseam. Tallboy 3 size XXL (505mm reach). When I discovered RAD I shortened the stem from 55 to 35mm and also employed some backsweep into the Enve M9 bars (cut to 770mm).
> 
> ...


Changing stem length has an impact on steering leverage. On a bike designed to have a stem going to no effective stem would make the steering very direct but also very twitchy. The stem is not just along for the ride.


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## chomxxo (Oct 15, 2008)

old_er said:


> Changing stem length has an impact on steering leverage. On a bike designed to have a stem going to no effective stem would make the steering very direct but also very twitchy. The stem is not just along for the ride.


You don't know what you're taking about, not having done it. useless conjecture. Lee talks about how negative stem even stabilizes the bike

Sent from my iPhone using Tapatalk


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## old_er (Dec 27, 2020)

chomxxo said:


> You don't know what you're taking about, not having done it. useless conjecture. Lee talks about how negative stem even stabilizes the bike
> 
> Sent from my iPhone using Tapatalk


????
I changed my stem from a 50mm to a 40mm on my Tallboy and immediately noticed a a twitchy-er steering. The stem acts as a lever on the steering axis. Longer will give you less movement on the steering axis for the input and shorter will give you more movement. This is simple leverage. If you have a stem behind the steering axis it will work the same but rider/ bar interference comes into play. I have ridden a modern mtb with a RAD calculated from my height of 5'11" of 80cm and I had some interference with my legs and the bars.

If Lee is your savior I have no problem but to say I don't know what I'm talking about or assuming I have never done it is ignorant on your behalf.


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## Stahr_Nut (Nov 7, 2006)

old_er said:


> If Lee is your savior I have no problem but to say I don't know what I'm talking about or assuming I have never done it is ignorant on your behalf.


I agree 100%. Bottom line is bike fit is not a simple subject and I don't understand how anyone can boil it down to one dimension. I've scanned through the four pages of posts in this thread and what I didn't see mentioned yet is headset spacers. In addition to stem length RAD can also be significantly adjusted by the addition or subtraction of headset spacers under the stem. But that will also generate a change in saddle height to bar drop which plays a huge part it bike fit, comfort and performance. I'm not about to go sacrificing my pedaling comfort for long days in the saddle endurance rides (which I spend the majority of my time doing) just to get my RAD number where it's "supposed" to be.


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## old_er (Dec 27, 2020)

Here is an interesting site to play on. It is a online stem comparison tool. It allows you to compare two bicycle stems with inputs for head tube angles, length, rise, and spacers.





Stem Comparison Tool | yojimg.net







yojimg.net


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## chomxxo (Oct 15, 2008)

Stahr_Nut said:


> I agree 100%. Bottom line is bike fit is not a simple subject and I don't understand how anyone can boil it down to one dimension. I've scanned through the four pages of posts in this thread and what I didn't see mentioned yet is headset spacers. In addition to stem length RAD can also be significantly adjusted by the addition or subtraction of headset spacers under the stem. But that will also generate a change in saddle height to bar drop which plays a huge part it bike fit, comfort and performance. I'm not about to go sacrificing my pedaling comfort for long days in the saddle endurance rides (which I spend the majority of my time doing) just to get my RAD number where it's "supposed" to be.


Not in this thread but covered extensively in Lee's book, it's RAAD you're looking for. If you're truly interested in a good fit then you'll do more than scan a few posts. Back to sleep...



old_er said:


> ????
> I changed my stem from a 50mm to a 40mm on my Tallboy and immediately noticed a a twitchy-er steering. The stem acts as a lever on the steering axis. Longer will give you less movement on the steering axis for the input and shorter will give you more movement. This is simple leverage. If you have a stem behind the steering axis it will work the same but rider/ bar interference comes into play. I have ridden a modern mtb with a RAD calculated from my height of 5'11" of 80cm and I had some interference with my legs and the bars.
> 
> If Lee is your savior I have no problem but to say I don't know what I'm talking about or assuming I have never done it is ignorant on your behalf.


Wrong. For one thing I've been critical of Lee on several points. Secondly, the "twitchy" thing is a newbie response to a parking lot ride. Anybody who rides fast will know that the bike becomes more stable at high speed with a shorter stem (as long as you have significant reach). Sssh, you're cluttering up the thread.


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## MtbrWNoMtn (Sep 10, 2020)

> What is your point then? Your original post was a bit vague.


comments like this are wrong and can mislead folks having a negative impact on their progression


> To get my bike fit down to the suggested RAD, I'd be in my 5'5" wife's bike, or I'd be running a 32mm stem with flat bars, and I'd be slamming my knees into the dropper lever.


Other's have already pointed out their comfort with lack of knee slam on their rad/rad- bikes; I'll share mine. My XL HT has been criticized on this board for having a short reach to begin with. From there I reduced stem, added more swept back bars, and moved spacers from under to over stem. My knees are in no danger of getting close to hitting the bars, no chance. I'm 4 inches taller than this poster on an XL, they wouldn't need to go to a small in my guestimation.



> the proper techniques require only a tiny bit of force from the front


I'm learning. Having leverage allows me to have some successes along the way working toward proper technique. Trials, bmx'rs, and DJ folks have no issue going to rear tire balance point at slow/no speed and hopping off a ledge, where I'd be in a dangerous OTB situation on said ledge. Now taking that away from the extreme one tire hop, I can now come off a log roll at my local trail because I can pop the front up enough to get off safely. Takes a lot of focus to carry in enough speed (it's a slow speed situation), I have to give a full down and back manual move HARD on my RAD- (many little rooty trail situations don't require much to pop over, this one makes me really focus on technique to get my max lift) to come off safe. OMG it feels so gnarly when I get it rightish, even have built to a wee bit of confidence with it. This is a progression, not a moment of going from crap technique to "it's effortless".

I think this comment can discourage folks that are working hard and getting better. Seems like he's indicating "well, I'm awesome, who cares about helping folks get to my awesomeness". I also think you take some of those ninja riders and stretch them out on a uber long bike, and they ain't gunna be doing that stuff.



> there are so many variables a formula based fit cannot account for.


RAD is about simplifying things down do a lever. Along the bottom bracket to center of grips line crossing, lee picked a point whose distance is scaled to the riders dimensions which he thinks gives folks enough leverage to do most of what is needed on a challenging trail. Start reducing that leverage, you're reducing the amount of torque you can generate into the bike period, you may not need that much torque, OK. It's not a "do it like this" it's a reference. A person out there with the same dimensions as me, but can bench 400 pounds, can increase that distance and generate the same force as I. Or they can keep the distance the same and generate more force/torque than I. From a pedals level position (not seated), these are the contact points, the person's measurement is relative to the riders body parts touching those contact points. Having more leverage is a recipe for success and fun.

Because of the lever simplification the approach is applicable to BMX, DJ, XC, Downhill, etc. Is this the one CORRECT distance? No, he has not claimed that. At that distance you will have good leverage, bring in for more, move out for less. Have more than you need? That's a problem I sure wish I had. Does that feel some like "I find it TOO easy to from a stand still go to rear one tire balance and can hop 4 feet from there in any direction while I wish I could only go 3 feet.... my Bunny Hops are just TOO high brah", um what? I've finally gotten to bunny hopping up regular sized curbs lmao, it took time, practice, and a heck of a lot of torque torque torque moves.



> Sure, you can have that conversation with my PT on how bad a cramped position is for my spine and hips.  I also can't ride bikes with too steep of a SA either.. same problem. The RAD works if you're gonna ride out of the saddle the whole time, but that's not realistic for 95% of the people out there.
> 
> Lee and I have an agreement: I can take skills lessons with him, and I think he's really a great instructor. But he cannot at all discuss bike fit with me. We agree to disagree on fit, and I respect him for that.


While I have no idea if you are at, above, or below Lee's skill level, I'd advice not censoring conversations on topics related to someone's knowledge base in which they are earning a living employing. Pro racers pay the Husband of Mrs. Likes Bikes to share his biking knowledge. I'm not going to pay a piano instructor to teach my little ones, but tell them to leave the chords out of it, even if they would accept my money to do so.

I did not sleep at a holiday inn express last night, and I'm not a physical therapist, but if you're trying to generate torque on a bicycle on which you have poor leverage, that is not contributing to the solution of your spine issues. Also, it sounds like you have a personal relationship with the MTB instructor in question. If you feel the need to check with him if he's aware the the body components of **** sapiens are not identically sized across the species, have at it. I'm good.

Finally there are several comments in here about seated riding. I'm not popping up 18inch ledges seated, only a little forward to back shift is needed to get over those 4 inch roots smoothly imo. However, you still have more leverage to row and anti row bringing everything in while seated. When I'm going over the gnarly stuff where I need significant torque, I'm out of the saddle.

I do apologize for my low chi moment calling others opinions bizarre. I will try to be more specific in points being made by others which I don't agree with and think they could hinder the progression of other noobs.

And my last quote 


> If you have enough leverage to pop up tough climbs, manual without exerting everything you can, yank a J hop you are proud of, u good. Riding a bike giving you enjoyment, NICE!


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## old_er (Dec 27, 2020)

chomxxo said:


> Not in this thread but covered extensively in Lee's book, it's RAAD you're looking for. If you're truly interested in a good fit then you'll do more than scan a few posts. Back to sleep...
> 
> Wrong. For one thing I've been critical of Lee on several points. Secondly, the "twitchy" thing is a newbie response to a parking lot ride. Anybody who rides fast will know that the bike becomes more stable at high speed with a shorter stem (as long as you have significant reach). Sssh, you're cluttering up the thread.


I live and ride in the northeast. Most of my riding is slower technical riding, if all my riding was fast a shorter stem length would be less noticeable.
Obviously this thread has become more of debate of mtb religion and less of geometry and physics.


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## 63expert (Jun 4, 2020)

Lee is a much better rider than I’ll ever be, and I’m sure that his instruction would improve my skill set. That being said, the “RAD” of my new bike, a 2021 Hightower in medium, is way longer than his height calculations would suggest that I have. My impression of my new bike is likely skewed as the bike I’m coming from is a 1996 GT Zaskar, also medium. Jumping on the 29” full squish from the 26 HT seemed so odd at first. The first mile or so of trail riding seemed a bit foreign, but after that the bike began to feel oh so right. I’m 5-8, so the medium Hightower is my recommended size. The bike has a 50mm stem. I cannot even imagine the RAD being shortened up to where the calculated distance should be. Maybe a shorter stem might feel better and I might give that a try. I know that climbing steep stuff the Hightower seems much more capable with more reach and wheelbase. 

Now for a slight rant. Lee’s term “RAD” seems to be an appropriation of an acronym to up the cool factor. Rider Area Distance. Area is a two dimensional measure of two distances. Distance is a one dimensional measure between two points. So “Area Distance” is a term like “Mass Weight”. 
A more correct term for the measure would be Rider Contact Distance, but then that wouldn’t make for the use of a kickass acronym. 

“Did you you see my dude shred the gnar??!!”

“ Yeah bro!!! That’s because he has his RAD so totally dialed!!!”


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## MtbrWNoMtn (Sep 10, 2020)

old_er said:


> I live and ride in the northeast. Most of my riding is slower technical riding, if all my riding was fast a shorter stem length would be less noticeable.
> Obviously this thread has become more of debate of mtb religion and less of geometry and physics.


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## old_er (Dec 27, 2020)

MtbrWNoMtn said:


> View attachment 1929475


I wasn't referring to your post as not using geometry or physics. Your post previous to this one has been the most detailed and specific on this thread.
Lee's concept of bike fit does have my interest but my analytical nature tends to search for information to understand what is presented.
I have a question for you. How did you get your RAD measurement? I have done mine three ways, the first using the calculated value base on height, the second using the marker against the wall as described in the JOB video, and third with a wood dowel with a hole in the end for a pencil using the same method a the second way. The results for me at 5'11" are 80cm, 78cm, and 83cm. My Tallboy's RAD is 85cm.


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## MtbrWNoMtn (Sep 10, 2020)

old_er said:


> I wasn't referring to your post as not using geometry or physics. Your post previous to this one has been the most detailed and specific on this thread.
> Lee's concept of bike fit does have my interest but my analytical nature tends to search for information to understand what is presented.
> I have a question for you. How did you get your RAD measurement? I have done mine three ways, the first using the calculated value base on height, the second using the marker against the wall as described in the JOB video, and third with a wood dowel with a hole in the end for a pencil using the same method a the second way. The results for me at 5'11" are 80cm, 78cm, and 83cm. My Tallboy's RAD is 85cm.


I've been drawn to the gadgetry, mechanics, and physics of it all. Bikes are friggen super kewl!! I did what they recommended on the JoB video and even made the string. I treat it as a reference eyeballing out the fact that I can't put the string inside if my bottom bracket and draw it straight to the string I had rubber banded from grip to grip (so like start from the outside of the bottom bracket and go maybe, an inch below the center of the grip to grip string). Lee was funny about how his earlier approach was more complex and after reading the comments he "independently and seprately from that thread" (was it on pink bike?) came up with the marker in the fist getting the distance from floor to your grab height.

He picked a distance he thinks is right, and yeah he has a TON of experience and skill so it's an opinion worth noting imo. Naysayers forget about that. Measure the distance you have now, reducing that distance increases torque, increase that distance and you reduce torque. If you have enough for your riding, you have enough. If your knee is hitting bar, you went too far and the force of the knee is going to jack up your torque anyway. However, given Lee's recommended distance, you are not in danger of knee smashing the bar, not even close.


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## jeremy3220 (Jul 5, 2017)

63expert said:


> the "RAD" of my new bike, a 2021 Hightower in medium, is way longer than his height calculations would suggest that I have.


The height calculations aren't very useful. They're just a rough estimate of your RAD. Actual RAD is going to be the distance that puts into a deadlift position. The wall measurement is more accurate. I wouldn't write off RAD if all you've done is estimate it based on height.


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## old_er (Dec 27, 2020)

jeremy3220 said:


> The height calculations aren't very useful. They're just a rough estimate of your RAD. Actual RAD is going to be the distance that puts into a deadlift position. The wall measurement is more accurate. I wouldn't write off RAD if all you've done is estimate it based on height.


I took an old broomstick and drilled a hole in the end to insert a pencil to use as a tool to measure body RAD. Your description of the deadlift position is much better than how I tried to describe it. I attached a couple of pictures. This method was the most consistent over repeated measurements.


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## MtbrWNoMtn (Sep 10, 2020)

old_er said:


> I took an old broomstick and drilled a hole in the end to insert a pencil to use as a tool to measure body RAD. Your description of the deadlift position is much better than how I tried to describe it. I attached a couple of pictures. This method was the most consistent over repeated measurements.
> View attachment 1929505
> View attachment 1929507


Makes good sense to me. Did that give you 80cm, 78cm, or 83cm? I was gunna say aim for the one in the middle rocky


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## MtbrWNoMtn (Sep 10, 2020)

FYI I went to this 30mm stem that's currently out of stock in USA








Shop






www.commencal-store.co.nz




and this high sweep back bar








3OX 16 Degree Aluminum MTB Handlebar


16° backsweep provides natural transition from arm to hand when in a stretch riding position. 4° upsweep brings elbows into position for dynamic riding style.




sqlab-usa.com




I was on the fence between the 12deg and 16 deg sweep back bar, but am glad I got more. Super comfy


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## old_er (Dec 27, 2020)

MtbrWNoMtn said:


> Makes good sense to me. Did that give you 80cm, 78cm, or 83cm? I was gunna say aim for the one in the middle rocky


That gave me the 83cm measurement.
I'm not sure what your rocky reference was.


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## MtbrWNoMtn (Sep 10, 2020)

old_er said:


> That gave me the 83cm measurement


Ahhh, nice. You're pretty close to what Mr. Likes Bikes is recommending. If you have any spacers below the stem you can move above to head in the more leverage direction


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## old_er (Dec 27, 2020)

MtbrWNoMtn said:


> Ahhh, nice. You're pretty close to what Mr. Likes Bikes is recommending. If you have any spacers below the stem you can move above to head in the more leverage direction


I have done some spacer moving since my last ride as my front wheel was losing some traction on seated climbing. I have to be careful about bar drop as I have basal joint arthritis in both thumbs. The results of wear and tear at 55. I'm using a PNW Range bar and Ergon GA-2 Fat grips which helps. I also have the GA-3 grips but found the GA-2 Fats work with my hands better.


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## MtbrWNoMtn (Sep 10, 2020)

old_er said:


> I'm not sure what your rocky reference was.


In Moscow, after Rocky Balboa said he was seeing 3 Ivan Drago's, Paulie told Rocky to hit the one in the middle. It was a dumb Rocky IV reference.



> I have done some spacer moving since my last ride as my front wheel was losing some traction on seated climbing. I have to be careful about bar drop as I have basal joint arthritis in both thumbs. The results of wear and tear at 55. I'm using a PNW Range bar and Ergon GA-2 Fat grips which helps. I also have the GA-3 grips but found the GA-2 Fats work with my hands better.


haha, I run those ga2's also. Sounds like, if you're going to tinker further, you want to focus on the X direction (bringing closer to you) vs Y direction (closer to the ground). Think that's bars and stem then, well frame too but I know I'm not going there for awhile. What stem are you running? Those bars, if I found the right ones in my quick google, appear to already have 10deg of sweep. The SQLabs 16deg may get you to RAD or RAD-, but you've got really nice bars you like.

Getting to RAD or RAD- would probably help you weight that front end easier on the climbs def maybe  I'd be surprised if you weren't a stronger more experienced rider than I already.


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## old_er (Dec 27, 2020)

Once thing to be aware of when reducing the spacers underneath the stem is it will increase reach.


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## RS VR6 (Mar 29, 2007)

I have short legs. I run no spacers under my stem.😆

I measured the RAD of my friend's Transition Spur. With a 40mm stem...it has a RAD of 82.5cm. My Evil Following V1 has a RAD of 80cm with a 50mm stem. Both medium. The Spur has a reach of 455 and the V1 Following has a reach of 419mm...the difference in RAD is only 2.5cm.


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## stripes (Sep 6, 2016)

MtbrWNoMtn said:


> comments like this are wrong and can mislead folks having a negative impact on their progression.


So you just come in here and **** on everyone's post because you're mad that people don't think about the geometry of this and would rather go ride their bikes in a comfortable way? Nice way to have a conversation.


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## MtbrWNoMtn (Sep 10, 2020)

stripes said:


> So you just come in here and **** on everyone's post because you're mad that people don't think about the geometry of this and would rather go ride their bikes in a comfortable way? Nice way to have a conversation.


I guess you didn't accept my apology. Not mad at all, my intention is to help. Peace


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## stripes (Sep 6, 2016)

MtbrWNoMtn said:


> I guess you didn't accept my apology. Not mad at all, my intention is to help. Peace


I didn't see it, but your post came across pretty harsh. We're good now though. Thanks for the apology, accepted.

What I don't get is why everyone is so insistent that they much match numbers. Fitting is so much more art than science that there's so much more to it than geometry and physics.

For example, there's a ton of posts on people wanted to get fitted for low back pain or sciatic issues. There's no way in hell RAD is going to fix that. Here's why: RAD takes into zero account the butt to hands measurement. This is the key fit for riding seated, which is where we spend most of our time climbing.

Lee is seriously fit. He's always going to optimize for himself and people who are much more athletic than I'll ever be. He also has different limitations than I do, or others do, so his fit accompanies his build more than people like myself who are outliers.


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## old_er (Dec 27, 2020)

What type of riding does Lee do? I see him in videos at pump tracks and feature parks. It is difficult for me to relate to him and his riding since it's not the same as what I ride. His spoken word is his own language which I find hard to take seriously. Maybe it's my age but I believe Lee is of similar age, I am 55.


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## stripes (Sep 6, 2016)

old_er said:


> What type of riding does Lee do? I see him in videos at pump tracks and feature parks. It is difficult for me to relate to him and his riding since it's not the same as what I ride. His spoken word is his own language which I find hard to take seriously. Maybe it's my age but I believe Lee is of similar age, I am 55.


Valmont Bike Park in Boulder, CO. He can ride trails, but he really likes hanging at the slalom and slope style.


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## old_er (Dec 27, 2020)

stripes said:


> Valmont Bike Park in Boulder, CO. He can ride trails, but he really likes hanging at the slalom and slope style.


I don't want to go to far off topic but you mentioned you have done some skills training with Lee. Are you able to take his techniques and apply them to the trail very well? I have have watched others such as Rich Drew and Jeff Lenosky and each has their own way of approaching and describing things. Jeff is from NJ which his home trails are very much the same as what I ride since we are in the NJ/NY area.


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## chomxxo (Oct 15, 2008)

stripes said:


> Are you saying strictly for children or adults or both?
> 
> I ride RAD+, assuming this means greater than your RAD number. Doesn't appear to be dangerous.


Well if you've measured it in the variety of ways mentioned and you still choose RAD+, then you've graduated from this discussion and can post elsewhere, because he's very clear about RAD+ not being a good idea in his book and videos.

I'm seeing posts from guys that are not very active on their mountain bike. If you're past retirement age or debilitated, all you do is ride up and down smooth terrain, RAD could help, but it's not intended for you.

I think the pun he chose is quite intentional. If you race DH, or get air, or race XC and are looking to push the limits of your bike handling and get faster, RAD is for you.


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## old_er (Dec 27, 2020)




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## stripes (Sep 6, 2016)

old_er said:


> I don't want to go to far off topic but you mentioned you have done some skills training with Lee. Are you able to take his techniques and apply them to the trail very well? I have have watched others such as Rich Drew and Jeff Lenosky and each has their own way of approaching and describing things. Jeff is from NJ which his home trails are very much the same as what I ride since we are in the NJ/NY area.


Yeah Lee does some AMAZING stuff that will never do (like the whale tail on the XL slopestyle), and while I don't agree with his fit, I'm able to apply a lot of things he taught me on the trail, particularly pumping shapes and cornering.

But, keep in mind that Colorado riding is not the same as California or the NE or the South or the PNW. Everywhere is gonna have their own styles of riding, and even types of bikes that might be more comfortable than others.

Most of the Colorado stuff is wide open, and either rocky, smooth, or loose (decomposed granite). NE riding is so different.


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## old_er (Dec 27, 2020)

stripes said:


> Yeah Lee does some AMAZING stuff that will never do (like the whale tail on the XL slopestyle), and while I don't agree with his fit, I'm able to apply a lot of things he taught me on the trail, particularly pumping shapes and cornering.
> 
> But, keep in mind that Colorado riding is not the same as California or the NE or the South or the PNW. Everywhere is gonna have their own styles of riding, and even types of bikes that might be more comfortable than others.
> 
> Most of the Colorado stuff is wide open, and either rocky, smooth, or loose (decomposed granite). NE riding is so different.


Thanks for the info. The northeast is definitely not wide open but there is some variety depending where your at. NY/NJ area is famous for rocks, roots, and undulating terrain. I am coming from an 02 Kona full suspension 26" wheel to a 2020 SC Tallboy I got back in January. I have been watching a few of these guys videos and practicing in my yard and on the trails. My neighbor's seven year old daughters get a kick out of the "older guy playing on his bike".


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## stripes (Sep 6, 2016)

old_er said:


> Thanks for the info. The northeast is definitely not wide open but there is some variety depending where your at. NY/NJ area is famous for rocks, roots, and undulating terrain. I am coming from an 02 Kona full suspension 26" wheel to a 2020 SC Tallboy I got back in January. I have been watching a few of these guys videos and practicing in my yard and on the trails. My neighbor's seven year old daughters get a kick out of the "older guy playing on his bike".


That's funny because it seems like it's a requirement to live in Colorado. There's a 75 year old guy who works in one of the Fruita bike shops that can ride circles around everyone a 1/3 his age.

I think it's great that you're out there working on your skills. One of my riding buddies is an old school XC racer and he does so much trials stuff that I watch him and want to be able to do it. At the same time, he won't jump off the stuff I will either.

I love the tech riding i had in NC. There's some seriously janky stuff out here that scares me here in Colorado, but I've been riding 30 years now, and it's worth it to me to ride what I want. At the same time, I know i need to challenge myself (in many ways), and as long as I'm out having fun, that's all that matters, right?

I had some chats today with other women riders, and a lot about fitting bikes. Honestly, people just care about being comfortable (male or female) that forcing their bike fit into a specific formula is going to make a lot of people quit out of frustration. Why are people so caught up in this anyway if their bike is exact RAD? It's not like it turns you automatically into Sam Hill or Rachel Atherton.


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## old_er (Dec 27, 2020)

stripes said:


> That's funny because it seems like it's a requirement to live in Colorado. There's a 75 year old guy who works in one of the Fruita bike shops that can ride circles around everyone a 1/3 his age.
> 
> I think it's great that you're out there working on your skills. One of my riding buddies is an old school XC racer and he does so much trials stuff that I watch him and want to be able to do it. At the same time, he won't jump off the stuff I will either.
> 
> ...


Your last paragraph rings so true. I have been riding on two wheels since I was four and when the bmx craze came through in the mid 70's we went crazy trying to emulate the pros. We didn't know about fit but could make those tweaked department store bikes do all kinds of crazy things. I got into mtb in the early 80's after seeing one in a magazine. I took old bikes and parts and got a close as I could to what I saw. My first real mtb was a 1984 Diamondback Trail Streak. I learned to hop onto picnic tables and whatever was around. Somewhere along the way I got serious with bikes on road and off and the fit obsession started. I have chased the elusive efficiency versus comfort balance for years. Every time I see a bike fit formula or theory I tend to dive into the research and go down the rabbit hole. Alex Bogusky made a great point on a recent interview on B1KER Bar to get out and just play on your bike. It really stuck in my head and brought me back to why I liked riding in the first place, to have fun. If RAD works great, if it doesn't nothing is dying or blowing up. Like Frank Zappa said "shut up 'n play yer guitar".


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## BansheeRune (Nov 27, 2011)

stripes said:


> That's funny because it seems like it's a requirement to live in Colorado. There's a 75 year old guy who works in one of the Fruita bike shops that can ride circles around everyone a 1/3 his age.
> 
> I think it's great that you're out there working on your skills. One of my riding buddies is an old school XC racer and he does so much trials stuff that I watch him and want to be able to do it. At the same time, he won't jump off the stuff I will either.
> 
> ...


Frankly, this whole RAD thing is nothing more than conjecture from one that has no idea of how others ride, what their physique is let alone, their expectations.
I for one have specific requirements that is placed into each of my CAD files for a custom frame that would contradict this faulty "equation" at the wholesale level.

I've done a number of size Marge frames in the years of frame building. Size Marge is a large HT/DT pair with the seat tube length of a medium. Good luck with RAD is all I can say of this topic since it is fundamentally flawed.

Rubbish!


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## old_er (Dec 27, 2020)

BansheeRune said:


> Frankly, this whole RAD thing is nothing more than conjecture from one that has no idea of how others ride, what their physique is let alone, their expectations.
> I for one have specific requirements that is placed into each of my CAD files for a custom frame that would contradict this faulty "equation" at the wholesale level.
> 
> I've done a number of size Marge frames in the years of frame building. Size Marge is a large HT/DT pair with the seat tube length of a medium. Good luck with RAD is all I can say of this topic since it is fundamentally flawed.
> ...


You have my curiosity, please elaborate on your theory.


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## jeremy3220 (Jul 5, 2017)

BansheeRune said:


> Frankly, this whole RAD thing is nothing more than conjecture from one that has no idea of how others ride, what their physique is let alone, their expectations.
> I for one have specific requirements that is placed into each of my CAD files for a custom frame that would contradict this faulty "equation" at the wholesale level.


Real RAD is the actual distance between your hands and feet in the deadlift position, not an equation. I think people are conflating estimated RAD with actual RAD.


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## MtbrWNoMtn (Sep 10, 2020)

Conjecture, religion, flawed... you all are silly








RAD- provides for more torque than RAD, RAD provides for more torque than RAD+. This is fact. If you row+anti-row the rollers, RAD and RAD- will produce more speed than RAD+. Row into the crest HARD, RAD and RAD- will produce more height and distance in the resultant jump. This skill translates to the trail directly in bunny hops, ripping berms, jumping, technical features, ups, downs, and arounds...

Someone said "tiny" amount of force.








Really? Tiny? More force more faster further and higher.

Don't need it? don't want it? makes you compromise in other areas? OK. I'm not going to end up on a BMX either.

These peeps have no benefit in computing RAD for this ride, seem to be enjoying the ride, good on them









I think the comfort argument may be confused with accustomed too. "RAD fundamentally flawed because seat tube length not accounted for"? Um no, your understanding of what RAD is, is fundamentally flawed.

Tell me you don't need the torque for your riding, or you need the stability a longer bike produces at speed down hill and conciously sacrifice nimbleness for that, or I really gave it a shot riding 3 times a week for 4 months and eliminated all other comfort impacting possibilities and a RAD setup is still not enjoyable for me or I was bunny hoppng so high that the thin air up there was making me light headed and I needed to reduce that altitude. The arguments being made against RAD are soft to say the least.


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## old_er (Dec 27, 2020)

MtbrWNoMtn said:


> Conjecture, religion, flawed... you all are silly
> View attachment 1929794
> 
> RAD- provides for more torque than RAD, RAD provides for more torque than RAD+. This is fact. If you row+anti-row the rollers, RAD and RAD- will produce more speed than RAD+. Row into the crest HARD, RAD and RAD- will produce more height and distance in the resultant jump. This skill translates to the trail directly in bunny hops, ripping berms, jumping, technical features, ups, downs, and arounds...
> ...


Interesting that if you actually apply Lee's techniques you show a picture that goes against them. Here's a picture of Lee with his notes in a similar application but more real world trail scenario. This is very similar to other skills teachers with the main premise of keeping hips over the bottom bracket.


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## dbltap (May 29, 2012)

Interesting. 6’ with avg proportions. I rode a medium ‘14 epic WC and kept having my knees hit the frame. Got a large and most of that has been eliminated. But the L ‘17 WC s-works just doesn’t respond like the M did.


Sent from my iPhone using Tapatalk


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## stripes (Sep 6, 2016)

Another school of thought, but works with modern geos: PVD/RAD Refined | Peter Verdone Designs

I haven't tried this yet but might be worth a shot.


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## old_er (Dec 27, 2020)

stripes said:


> Another school of thought, but works with modern geos: PVD/RAD Refined | Peter Verdone Designs
> 
> I haven't tried this yet but might be worth a shot.


It is interesting. I saw this on another thread on the forum and have been reading about it.


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## .je (Jan 15, 2019)

My new geo bike gas a long RAD so I calc'd & measured RAD and got a low number, applied it with a short stem it was much easier to wring around and lift... but weight was now so far back it was unbalanced unless I was uncomfortably leaned forward over my arms. Didn't want that. 

I found it comfy and easier to manipulate it with the stock longer stem & even more stack & RAD... which put it in line with other new bikes. Is that backward?


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## MtbrWNoMtn (Sep 10, 2020)

.je said:


> My new geo bike gas a long RAD so I calc'd & measured RAD and got a low number, applied it with a short stem it was much easier to wring around and lift... but weight was now so far back it was unbalanced unless I was uncomfortably leaned forward over my arms. Didn't want that.
> 
> I found it comfy and easier to manipulate it with the stock longer stem & even more stack & RAD... which put it in line with other new bikes. Is that backward?


It's backwords from RAD, but ride what you like. Sounds like you gave it a go and while you saw the benifits, the drawbacks you experienced outweighed those for your riding. Am curious if you stuck with it longer if it would start to feel right to you over time but...it's your shred stick, enjoy!


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## .je (Jan 15, 2019)

The control was fantastic but I couldn't deal with leaning over my arms that much. A ready position was unstable and the front wandered when pedalling, weight not centered, especially for a long front end like these. I find that more stack accomplished a lot of that leverage (some other bikes are already like this so it does not seem unusual). Maybe I'm just proportioned that way.


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## Varaxis (Mar 16, 2010)

@MtbrWNoMtn your logic is off. The leverage/torque they speak of relates more to the amount of power generated from changing the BB to grip length, and the body's various lengths.

You have to acknowledge that these guys are laymen. These revelations have come to them over the years. They don't communicate them that clearly, but there's certainly some insight to it.

Think of it this way: when you pick up a heavy object like a kettlebell, you get more lifting power when the object is a certain distance from your feet. If someone offers an illustration based on this fact, some people might believe it. They'd measure it and think, no wonder it's hard for me to lift my front wheel up! My bike's reach is so more much than this measurement! That grips are so far forward! It's like me trying to swing a kettlebell up from an already stretched position! You have to pick the weight of the upper body up + the kettlebell without help from the legs/feet!










Lee has the motivation to stay invested in his RipRow thing. When you row, you are using your hips to sort of anchor that movement. Imagine trying to do the row movement with your hands raised to pull towards your shoulders or lowered to pull towards your quads, and you'll likely imagine it's not as strong. It like trying to imagine using the chest or shoulders as the anchor point.

It's about taking advantage of using your natural strength, especially with this row and anti-row movement. RAD has useful insight, in bringing attention to human mechanics and making the bike fit it, but there are obvious flaws still. People are using RAD as a way to judge bike geo tables, not too unlike judging by the horizontal top tube or seat tube length. These figures are useful for determining seated pedaling fit, but there's the problem of people being religious about it, condemning bikes for not fitting their expected numbers. RAD's a modification of judging by reach and stack, for when out-of-the-saddle fit matters enough, tying it to a person's range of movement.

Being developed by a layman is the other flaw. The foundations are just plainly questionable and there's just a lot of confusion/stupidity surrounding it. I could talk myself up as being a has-been racer, coaching people regularly, advising them on bike buying decisions too, doing the "customer testimonial" trust-building video thing. I can spit out illustrations that are meaningless, that people take too literally like the skeleton one above. It merely has to "seem" right for people to get their interest piqued. Watch someone go out and actually measure themselves according to this image, and use whatever bias they have to connect with reality. _sarcasm on_ "This measurement is so much shorter than my new bike's reach, it's no wonder I feel like that bike is basically unrideable compared to my old favorite!" _sarcasm off_

Another major flaw is that it's not for everyone. I'm 5'7. I regularly do epic rides (multi-hour long outings). This by itself should be a huge hint that RAD is not a high priority. I don't have the endurance to ride actively out of the saddle to be the suspension for my bike. I value the bike doing a lot of the work for me, especially after I get tired. I have noticed performance gains from upsizing on bikes for the riding I like to do.

I don't credit extra reach as being the reason behind the extra performance behind upsizing. I can tweak my other smaller bikes with anglesets and longer forks, noting improvement in the performance I like for the riding I do. I wasn't so certain that it was the wheelbase lengthening since I liked certain bikes like my ROS9, Thunderbolt BC Edition, since I liked them more than I liked some long wheelbase bikes. I felt more balanced on some bikes in size med, rather than size large, like the Yeti SB150.

My ongoing experimentation led me to find the front:rear weight distro sweet spot through geo. One that made standing in a strong position the best place to be. Not having to shift my weight to the rear to compensate for the geo distributing too much weight on the front made things feel so natural, intuitive, and effortless. That feel of the bike basically reading my mind, doing what I was thinking of doing, in a predictable enough manner that I am doing 2-wheeled drifts... it's a mind-blowing experience that I'm trying to re-create reliably. I think the reason why I don't feel it on a lot of modern bikes, despite good balance, is because the tires are not matched.

I've had to define what a strong position is. It's not really one that's close to a deadlift, IMO. I feel strong when I engage my core (hip/pelvic area or belly button as my center) to carry the weight of my upper body. I feel like I have a lot of control when I'm not pushing/pulling on the bars, allowing my upper body to move freely. Basically, it's the basics of "heavy-feet and light-hands" and "bike-body separation" being implemented. It's still unclear how I can optimize bike geo and fit to make the rider's resting/neutral position be this, but I know there's a big difference in terms of weight distro between sitting and standing position.

We all have developed some sort of system to be picky about bikes. Some of us went through a process that fleshed out more insight through experimentation than others. What makes a bike stand out from others, being potentially the "bike-of-the-year" winner? We're basically betting thousands of dollars on this, picking one bike out of many, to learn from experience. It's like a process of trial and error...

Anyways, the cross-training thing is weird. Training specificity is a real thing. I don't lift weights or do that BMX stuff, but I do walk, run, jump, and whatever. If I can make my biking use that, and maybe make my biking help it, that would be better for me. What I consider to be a "pump" is merely letting the bike pitch up and down freely by itself, not letting my body be dead-weight that gets in its way.


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## MtbrWNoMtn (Sep 10, 2020)

Varaxis said:


> I am doing 2-wheeled drifts... it's a mind-blowing experience that I'm trying to re-create reliably.
> [/QUOTE]


VIDEO!!! Rock On

Yeah it's a simplification. Even to get to a particular BB to center of grip contact points distance on a particular bike there are multiple ways to get there and they will feel different. The simplification is true though that you will produce more torque and that is used lots of ways in MTB. Ack, I'm a noob, learning more everyday. Know what it feels like to exert force without leverage, then shuffle things around and ahh that was easy.

An older Syd and Macky video popped up in my queue recently, Lee was the guest. He talked about taking something complex and simplifying it as a general approach for him.

Still, a particular person on a particular bike, reduce that distance and pop that tire in the air with less force. That's my story and I'm sticking to it, well at least for today


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## ashwinearl (Jan 2, 2004)

Varaxis said:


> . I think the reason why I don't feel it on a lot of modern bikes, despite good balance, is because the tires are not matched.


This is interesting. I tried to remember the last time I had matched front/rear tires and it was some Maxxis Tomahawks, and I recall it was a great feeling. I need to experiment with this again.
Any more insight of what frame parameters (reach, stack, chainstay length, wheelbase...) that have predicted good fit, balance for you would be appreciated.


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## Varaxis (Mar 16, 2010)

ashwinearl said:


> This is interesting. I tried to remember the last time I had matched front/rear tires and it was some Maxxis Tomahawks, and I recall it was a great feeling. I need to experiment with this again.
> Any more insight of what frame parameters (reach, stack, chainstay length, wheelbase...) that have predicted good fit, balance for you would be appreciated.







I agree with everything this guy says except for the way he comes up with weight distro. He's trying to figure it out with math, and a simple equation, whereas I tried it with scales under each wheel and make my own judgment based on my preferred positioning and my best handling bikes in my quiver.

The RC:FC ratio (division) thing he does is flawed. I had my own Grim Donut custom-made with sliding dropouts, and tested with short wheelbase bikes, and find it's not a good way to determine weight distro.


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## mtskibum16 (Apr 14, 2009)

Impetus said:


> I've really come to the conclusion that RAD just doesn't work for me.
> I have a degree in biomechanics, and am a sports/ortho physical therapist, so I can follow the logic of what Lee says, but neither of my bikes are even in that same zip code as my calculated RAD.
> I'm 5'9", my measurement with the marker in hand on the wall is IIRC 735mm. Both my FS and my hardtail have a RAD of something in the low 800s! Neither has a long reach- the HT is a 450 reach, the FS is a 445. I'm running 50 and 55mm stems with 780 bars. To get my bike fit down to the suggested RAD, I'd be in my 5'5" wife's bike, or I'd be running a 32mm stem with flat bars, and I'd be slamming my knees into the dropper lever.
> 
> I've done the ladder-test and the bars are juuust short of being comfortably in hand, I'm also really comfortable on both my bikes, so I don't sweat it.


You must have incredibly long arms or something! I'm 5'9.5" with my a wingspan about 1" shorter than my height and measure a RAD of 838mm (33"). 


jeremy3220 said:


> The exception would be people with long arms since the longer your arms for a given height, the shorter your wall measured RAD would be. It's not perfect. Maybe do the wall measurement then add 1/2 your ape index?


Or short arms. Like the other post I quoted. He and I are only .5" apart but somehow his RAD is 735mm and mine is 838mm?? I don't see how arm length is all of a sudden the number one factor in a bike's fit. Or why of the two people very similar in size the one with longer arms would want a smaller bike?


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## Blastoff (Aug 15, 2021)

chomxxo said:


> In reading both threads I see a consistent misunderstanding of what RAD is and how to measure it. I bought the book "Dialed" and it definitely explains this in detail.
> 
> That said, the book includes recommended reach measurements that are outdated. Reach is relative to the seat tube angle and older bikes at 72*, for instance, have shorter reach than a 75* STA new bike with longer reach.
> 
> ...


Reach, as measured by all bicycle manufacturers, has absolutely no relation to the seat tube. All reach measurements are obtained by drawing a vertical line up from the center of the bottom bracket and a horizontal line back from the center of the top of the head tube. The horizontal distance from top center of the top tube to where it intersects with the vertical line drawn up from the bottom bracket is the reach. Just look at any frame geometry schematic on any website.


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## emu26 (Jun 23, 2008)

Blastoff said:


> Reach, as measured by all bicycle manufacturers, has absolutely no relation to the seat tube. All reach measurements are obtained by drawing a vertical line up from the center of the bottom bracket and a horizontal line back from the center of the top of the head tube. The horizontal distance from top center of the top tube to where it intersects with the vertical line drawn up from the bottom bracket is the reach. Just look at any frame geometry schematic on any website.


I had a guy on another forum try to tell me that reach was an active measurement that changed as the angle of the bike going up or down a trail changed. No matter how much I tried to explain the above and that it was a static measurement used as a tool to compare frames he wouldn't have it.


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## DIRTJUNKIE (Oct 18, 2000)

emu26 said:


> I had a guy on another forum try to tell me that reach was an active measurement that changed as the angle of the bike going up or down a trail changed. No matter how much I tried to explain the above and that it was a static measurement used as a tool to compare frames he wouldn't have it.


Those kind of guys make opening up threads about technical matters all worth it.


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## chomxxo (Oct 15, 2008)

Blastoff said:


> Reach, as measured by all bicycle manufacturers, has absolutely no relation to the seat tube. All reach measurements are obtained by drawing a vertical line up from the center of the bottom bracket and a horizontal line back from the center of the top of the head tube. The horizontal distance from top center of the top tube to where it intersects with the vertical line drawn up from the bottom bracket is the reach. Just look at any frame geometry schematic on any website.


Technically what you’re saying is correct but you’re also missing the boat on both RAD and STA. So back to my point: if you measured the reach on a 2012 bike vs a 2022, the new bike would be longer, but it actually needs to have a much longer reach measurement because conventional wisdom about KOPS has been defied and we’re good with putting the rider more forward than that. Setback posts used to be popular as well.
So yes reach is a measurement that doesn’t change but it’s never directly related to your body measurements, and unchanging, like RAD is. Study a bit more before whipping out Wiktionary


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## ashwinearl (Jan 2, 2004)

stripes said:


> The point of the RAD measurement is to get people to size down one or two sizes, so you're not wrong.
> 
> I rode an XS at 5'5" based on that. Too twitchy, and I was way too crunched up. Now i get way ledgy trails were particularly nerve wracking.
> 
> Two years ago got on a medium and my riding has improved significantly. Body feels much better, and my bike handling is much better too because the twitchiness is gone.


Wow xs to medium..

I am in the same situation. 5'4" but also long legs short torso. Been on XSs. I want to try going bigger but sizing up combined with the way geometries have also sized up has me nervous. I am starting with an -1 angle set and my Rocky Mountain altitude in the steepest setting for the steeper STA just to see impact. but reach will still be short, even shorter w/o chaning the stem.


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