# 68 degree HTA too slack for rigid?



## coke (Jun 7, 2008)

I'm having a custom 29+ rigid singlespeed built with a 490mm ac fork, and based upon my previous bikes, I'm thinking a 68 degree head tube angle will be about right. My concern is that I've never ridden a rigid bike that was any slacker than 70 degrees. 

I've had hardtail and FS bikes as slack as 67 and they felt pretty good on all my local trails. The only time it was a problem was on very steep uphill switchbacks, where I would be seated, the front would be slightly unweighted, the fork would reach full extension, and the rear shock would compress. This would result in something slacker than 67, and it was somewhat floppy and cumbersome. 

On climbs like that while riding a rigid singlespeed, I'm typically out of the saddle and don't have to worry about rear suspension compressing, so I'm thinking I can get by with 68.

Does anyone have any thoughts on this? Should I go to 68.5 or 69? I currently have 72 and 71 degree hta rigid singlespeeds and they are definitely too steep. I have a 67.5 hardtail with 120mm fork and it feels about perfect. I have a 67 full suspension with 150mm fork, and it feels good in most places but is a little too slack on some of the slow technical sections of trail.


Thanks!


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## yzedf (Apr 22, 2014)

My standard 29er is roughly 68 degrees HTA rigid and I think it's great


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## Sparticus (Dec 28, 1999)

I'd go 68 degrees for sure. Certainly no steeper anyway.
=s


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## life behind bars (May 24, 2014)

What's the frame builder have to say?


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## coke (Jun 7, 2008)

He thinks it's a little too slack, but doesn't have any personal experience with this type of setup. Their standard offering is closer to 70.


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## life behind bars (May 24, 2014)

I have to ask, what motivates you to go that slack in the first place? Does it fit your particular style or are you chasing the flavor of the week? Going that slack usually involves some other geometry tweaks like a longer front center, short chain stays and a steeper seat tube. In for a penny, in for a pound as they say.


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## coke (Jun 7, 2008)

I'm basing all the geo off of my past bike experience. 

From the bikes I've owned, 68-69 seems to be the sweet spot for our trails. I've just never had the opportunity to ride a rigid bike with that geo, and not sure if there are any unexpected downsides.


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## chayzed (Mar 30, 2010)

Don't forget the fork offset which affects the 'trail' measurement will also affect the overall handling... Just saying..


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## coke (Jun 7, 2008)

I've been working with the builder on trail. It's easy for me to compare hta and other numbers between my bikes, but i don't have a good idea of what trail would be optimal.

This is the fork I plan to use NINER BOOST RDO MTB FORK


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## Cotharyus (Jun 21, 2012)

All I can do is a little comparison for you. My SS has a 70 degree HTA when spec'd with a 100mm fork, or equivalent A/C. I rode it like that for a while, and in the mode, it was the slackest bike I'd ever owned. I posed no problems for me. Due to age, milage, and abuse (on me, not the bike) I elected to put a suspension fork on the bike, and ended up with a 120mm fork, making the HTA 69 degrees. I'd say it works just fine - but you're talking rigid. Well. I lock my fork out (bar mounted lock out, it's great...) for climbing and still, no issues. Not sure how much another degree would affect things, but maybe this helps a little?


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## *OneSpeed* (Oct 18, 2013)

coke said:


> I've been working with the builder on trail. It's easy for me to compare hta and other numbers between my bikes, but i don't have a good idea of what trail would be optimal.
> 
> This is the fork I plan to use NINER BOOST RDO MTB FORK


That's good to hear, your going to want a high offset fork with a "slack" rigid bike.

My thoughts: My Krampus was 69, but had long chainstays. It climbed ok but was slow in tight turns. My old Kona Unit was 71 and turned super quick, in a good way, I liked it on local trails that are tight and twisty.

Krampus + dropper was a pretty fun setup even without suspension. Only complaint on that frame was the chainstays. I just sold it and plan to build a 29+ wheelset for the Wednesday. I like the geo better, and I have a lefty on there. :thumbsup:

I just went through the custom frame design process myself. I ordered a SS 29er frame. Originally I wanted a 70 degree HTA. My concept was modern XC geo. After deciding on a 51mm offset fork, I decided to go with a 69 HTA. I want the bike to be snappy and quick turning, Short chainstays will help (425-430 iirc), but I think I'm OK with where I ended up. (BTW this is all on a big XL frame). I don't have it yet so I can't give a ride report other than it's freakin Awesome!!

There are a couple other factors that should be taken into account though. Front-center and BB drop are probably the next most important. And of course personal preference and local terrain. HTA alone is not enough information to determine how your bike will handle. If your going for a "trail" SS then I think you hit the nail in the head.

If I lived in an area that had longer, faster, flowier (what? it's a word) downhills, I would go slacker, but as it is I prefer to climb and need a quick bike for tree lined trails.


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## coke (Jun 7, 2008)

*OneSpeed* said:


> That's good to hear, your going to want a high offset fork with a "slack" rigid bike.
> 
> My thoughts: My Krampus was 69, but had long chainstays. It climbed ok but was slow in tight turns. My old Kona Unit was 71 and turned super quick, in a good way, I liked it on local trails that are tight and twisty.
> 
> ...


They use a titanium plate that connects to their chainstays and it's one of the reasons I chose this builder. I need good vertical compliance and the plate is designed to flex. It does limit how short chainstays can be though. It's looking like 437mm with a 3" tire. Can go a little shorter with a smaller tire.

Still discussing bb height but they recommend 12.75". It's very rocky here and I don't want to go too low


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## azjonboy (Dec 21, 2006)

My blacksheep, rigid, has a 69.5 HA. It climbs well, no wandering, in steep technical stuff.
The fork is based off the Reba and has a 46mm offset.

My 2015 Les had a 69. HA at 120mm. I had a Reba on it , also 46 mm offset. I wandered like crazy on steep, technical climbs. 

My 2017 Les has a 69 degree HA, also at 120 mm. I put the Fox 34 Fit on it, with 51 mm offset. It handles much better with the higher offset.

Personally, I'd go with 69 degree head angle. I'd also go with the taller bottom bracket. My Blacksheep has a 12.9" bb height, the Les has a 12'1" bb height. I hate the lower height of the Les for my riding. 

I'm in Arizona and have lots of rocks, so the higher bb is a must have.

My Blacksheep frame is 19.5" with a 24" tt. I also went with a 5" head tube to give the front end more stiffness. 

Two questions for you to consider. Are you thinking 68 degrees for descending? How fast are you really going to descend those rocky trails on a rigid fork? 

Good luck!!


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## *OneSpeed* (Oct 18, 2013)

Another factor I forgot to mention is stem length which can make a difference. I guess I was just assuming everyone aims for a short stem now-a-days. 

azjonboy, are you experiencing wandering on a SS while doing standing climbs? or seated and spinning on a geared bike?


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## yzedf (Apr 22, 2014)

azjonboy said:


> My blacksheep, rigid, has a 69.5 HA. It climbs well, no wandering, in steep technical stuff.
> The fork is based off the Reba and has a 46mm offset.
> 
> My 2015 Les had a 69. HA at 120mm. I had a Reba on it , also 46 mm offset. I wandered like crazy on steep, technical climbs.
> ...


My 68 degrees rigid descends pretty darn fast, I have no problem keeping up until things get rather hectic. Sure, I'm a bit faster with my Rockshox, but that's really only when I miss a line. Not to mention my RDO fork is way stiffer than any XC squishy fork is, none of that horrible twisting and flexing, especially noticeable when riding down a rocky shoot that the front end would normally dive on and provide a few pucker moments. Of course I'm almost 200lbs and riding on terrain that most people use 120mm or more full suspension bikes on. I'm not a horribly fast rider, but I am usually top 1/3 or so on Strava riding rigid.


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## azjonboy (Dec 21, 2006)

Experienced wandering on the 2015 Les, SS or geared, when seated, climbing technical stuff.

Yzedf - descending fast on a rigid bike is a blast! But there are times and places on our trails where that's also a nightmare


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## teamdicky (Jan 12, 2004)

Someone else's theory on one thing combined with my own.

I think that suspension forks work well with a slacker HTA. Angle of impact better in line with the fork's action.

That said, the opposite from rigid forks. The only compliance you get from a rigid fork is fore/aft flex. Put the fork legs more in line with the impact, you're gonna feel the hits more.

And yes, I've tried this out before.

500mm A-C Roca Roka ti fork with high 69'ish°/low 70'ish°:










470mm A-C ENVE with 71° HTA:


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## coke (Jun 7, 2008)

azjonboy said:


> Two questions for you to consider. Are you thinking 68 degrees for descending? How fast are you really going to descend those rocky trails on a rigid fork?
> 
> Good luck!!


It's more for cornering and overall stability than pure descending. I love how my slacker bikes corner. With my steeper bikes, they are almost twitchy and have very little forgiveness for errors made while cornering. With my slacker bikes, I feel like I can shift my weight and move around more in corners, and they also provide more forgiveness when tires start to slide.

Descending is a strength of mine, and I do fairly well on my current bike. Last year I raced my rigid singlespeed in the geared class against hardtails and FS bikes. I usually don't loose much time on descents, except for the really rough courses. Regardless of geo, rigid bikes are limited when it gets rough.


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## azjonboy (Dec 21, 2006)

I hear what you're saying about Wanting to rail corners. Both of my bikes excel at tight handling and hard cornering. Will a 68 degree HA be better or worse? I don't know. I do know my bikes handle anything i throw at them. The Blacksheep is a better handling bike than the Les, but it was custom designed whereas the Les is off the shelf. 

If you're coming from a 71 or 72 degree bike, the 69 will be a noticeable change. From 69 to 68? Probably not as noticeable as the first change.


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## evoracer (Feb 26, 2008)

My old Nimble9 SS with 130 fork felt cumbersome/floppy on shallow, slow climbs while seated. Standing while on slow technical, climbing, or fast sections was never an issue. Bike was a hoot!

My current SC Highball SS with full rigid 490ac fork doesn't have any issues up or down. Another fun bike.


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## eri (Sep 4, 2012)

teamdicky said:


> Someone else's theory on one thing combined with my own.
> 
> I think that suspension forks work well with a slacker HTA. Angle of impact better in line with the fork's action.
> 
> ...


If I was the op i'd drop this custom builder and try to buy Dicky's bike (or have a copy made.)

Look at that thing! Short chainstays, low top tube, bent seat tube but straight at the top for a dropper. Drewl.


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## coke (Jun 7, 2008)

eri said:


> If I was the op i'd drop this custom builder and try to buy Dicky's bike (or have a copy made.)
> 
> Look at that thing! Short chainstays, low top tube, bent seat tube but straight at the top for a dropper. Drewl.


His bike is one reason I started looking at ti as an option, but I don't believe it was designed with clearance for 29x3" tires.

I'm going with short chainstays, but they aren't too short. With the 3" tire it will be about 17.2. I have health issues, and one of the primary reasons I'm having this bike built is for comfort while in the saddle. I know there are lot of factors, but I think in general you'll sacrifice a little compliance as the chainstays are shortened.

Going with 12x157 super boost

They can do a curved seat tube if needed at no extra charge, but as of now I'm not sure it will be needed.

I'm doing a curved top tube to get more standover. Should allow a little more post to be exposed too for more comfort.

I'm getting internal routing for a dropper post.

No routing for derailleurs since this bike will always be a singlespeed.

I have that same enve fork on my current bike. It's a really nice fork, but for this build I'm going with the new Niner since it has a longer A-C and boost spacing.

Here's a pic of their base design. I'm making a LOT of changes though, and of course mine will be set up as a rigid SS.


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## coke (Jun 7, 2008)

teamdicky said:


> Someone else's theory on one thing combined with my own.


I'm also a fan of Nox wheels and pink. I was 100% decided on Nox Kitsuma 29 for this bike, but was a little concerned with the width for a 3" tire and it also seemed a little heavy. After speaking with the builder, we've decided to go with Kappius laced to project 321 hubs. These may be a little wide for 2.6 & 2.8 tires, but as of now I don't plan on running that size. If I'm going to a race where I feel the big 3" tires will be too much of a disadvantage, I have a lighter 29er rigid SS I can use instead of this bike.

Kappius rims have 40mm internal width and weigh 435g. I know they won't be as durable as nox, but I'm thinking that as long as run enough air to avoid rim strikes they should be fine.

Here's a pic of the setup on my current bike. Nox rims, enve fork, and pink hubs. This setup has been flawless and I've never had to touch a spoke, even after a few hard rim strikes.


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## eri (Sep 4, 2012)

coke said:


> His bike is one reason I started looking at ti as an option, but I don't believe it was designed with clearance for 29x3" tires.
> 
> I'm going with short chainstays, but they aren't too short. With the 3" tire it will be about 17.2. I have health issues, and one of the primary reasons I'm having this bike built is for comfort while in the saddle. I know there are lot of factors, but I think in general you'll sacrifice a little compliance as the chainstays are shortened.


Wow. Looks great. Bent top tube is such a good idea. Why wouldn't you get the bent seatstay too?

Assuming bike will have sliders... build the bike with all the room it can provide. That way you can run a shorter chainstay if you feel like it. Put on a regular 29x2.35 in the back and then choose your csl.

Build the bike so you can make the chainstays too short, then extend to where you like it.

At least that's what I'd do.


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## coke (Jun 7, 2008)

eri said:


> Wow. Looks great. Bent top tube is such a good idea. Why wouldn't you get the bent seatstay too?
> 
> Assuming bike will have sliders... build the bike with all the room it can provide. That way you can run a shorter chainstay if you feel like it. Put on a regular 29x2.35 in the back and then choose your csl.
> 
> ...


Seat tube angle looks good as is. I think sometimes a bend is added for tire clearance, but the builder says the tire will hit the rear plate before it gets too close to the seat tube.

Yeah the frame will have sliders. Trying to allow for the ability to run slightly larger or slightly smaller tires.


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## hardmtnbiker (Feb 22, 2005)

Going with 12x157 super boost

I've never heard of Super Boost single speed specific hubs. But I know geared hubs will work with more spacers, then can serve double duty if you wanna use geared.
I have 2 rigid SS bikes, my Sir9 has a steep 70 HTA with the Niner carbon fork. My Seven has 68.5 with the ENVE MTN fork (offset to the front)but I run fat 2.6 tires on i35 rims or 3" tire on i40 rims. So the HTA is actually closer to 67.5 or 68. 
Personally I enjoy the slacker HTA, the bikes are small and have short wheel base. True the slacker HTA takes a little more finesse on steep climbs but the descents are way better. The steeper HTA take more finesse on the descents. 
Good luck, and please post pics when it's completed.


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## bikeny (Feb 26, 2004)

Coke, sounds like an interesting build you're working on. I like the decision to go 157mm for the rear, I did the same on my custom build last year. I'm just using a standard 157mm DT hub, don't know if any Super Boost hubs are actually available? It's the same as the old 157mm Downhill standard, so any of those hubs will work. I swap between SS and geared, and what I did was get a steel freehub for my DT hub. I keep the cassette on the original aluminum freehub, and put the SS cog and spacers on the steel one. Swapping is as easy as pulling one off and sliding the other one on. The flange spacing is not as wide on the old 157mm hubs as on the new Super boost, but at least it's symmetrical. I also managed to find a really rare and sweet DT Swiss 440FR 157mm singlespeed hub. I haven't done anything with it yet, but the flange spacing is huge, should build a bomber wheel!

Also, what width BB are you going with? I went 83mm to better match up with the wider rear end, and that also allowed the builder to make the CS length even shorter, as it freed up precious room in the area. May be worth asking the builder about it.

Oh yea, mine was build to also take 27.5x3.8 tires for my winter setup.








Edit: Forgot to mention, I went with 68 deg. HTA and am very happy with it. I have to 'throw' it around a bit in the tight stuff, but otherwise all good. I also had my builder extend the headtube up so I could get my bars up high without tons of spacers.


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## coke (Jun 7, 2008)

hardmtnbiker said:


> Going with 12x157 super boost
> 
> I've never heard of Super Boost single speed specific hubs. But I know geared hubs will work with more spacers, then can serve double duty if you wanna use geared.
> I have 2 rigid SS bikes, my Sir9 has a steep 70 HTA with the Niner carbon fork. My Seven has 68.5 with the ENVE MTN fork (offset to the front)but I run fat 2.6 tires on i35 rims or 3" tire on i40 rims. So the HTA is actually closer to 67.5 or 68.
> ...


Thanks for the comments about your bike. I couldn't decide between 68 and 69, so now we're looking at 68.5 lol.

The rear hub is a geared hub. I made the mistake of using ss specific hubs in the past. I swap parts between bikes and buy/sell way too often, and a ss hub severely limits options and resale.


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## coke (Jun 7, 2008)

bikeny said:


> Coke, sounds like an interesting build you're working on. I like the decision to go 157mm for the rear, I did the same on my custom build last year. I'm just using a standard 157mm DT hub, don't know if any Super Boost hubs are actually available? It's the same as the old 157mm Downhill standard, so any of those hubs will work. I swap between SS and geared, and what I did was get a steel freehub for my DT hub. I keep the cassette on the original aluminum freehub, and put the SS cog and spacers on the steel one. Swapping is as easy as pulling one off and sliding the other one on. The flange spacing is not as wide on the old 157mm hubs as on the new Super boost, but at least it's symmetrical. I also managed to find a really rare and sweet DT Swiss 440FR 157mm singlespeed hub. I haven't done anything with it yet, but the flange spacing is huge, should build a bomber wheel!
> 
> Also, what width BB are you going with? I went 83mm to better match up with the wider rear end, and that also allowed the builder to make the CS length even shorter, as it freed up precious room in the area. May be worth asking the builder about it.
> 
> ...


This is the hub I'm going with. It's a 12x157 geared hub. 291g (I'm trying to keep this build around 20 pounds), 216 points of engagement, QUIET, and ceramic bearings https://project321.com/product/dh-150-157-rear-hub/

BB will be 83mm. I've had fatbikes before, and the extra width doesn't bother me


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## hardmtnbiker (Feb 22, 2005)

I'm sure you'll be fine on the climbs with 68.5 and fun on the descents too. 

Yeah the SS specific hubs are limited application and I'm sure the a geared 12x157 has some pretty widely spaced flanges for a strong wheel build.
I haven't rode a geared bike in almost 3 years and the 29er's I tried back then had noticeable wheel flex with 142x12 and 148x12. I found out that SS specific 135/142 even had wider flanges than gears 148. Just FYI.


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## coke (Jun 7, 2008)

hardmtnbiker said:


> I'm sure you'll be fine on the climbs with 68.5 and fun on the descents too.
> 
> Yeah the SS specific hubs are limited application and I'm sure the a geared 12x157 has some pretty widely spaced flanges for a strong wheel build.
> I haven't rode a geared bike in almost 3 years and the 29er's I tried back then had noticeable wheel flex with 142x12 and 148x12. I found out that SS specific 135/142 even had wider flanges than gears 148. Just FYI.


The niner one 9 I posted above has a 142x12 onyx SS hub laced to nox teocalli rims. I'm 155 pounds, and have no flex issues at all. I have very little room between my chainstays and tires, and thanks to the stiff wheel it doesn't rub. I had roval traverse sl fattie wheels on there before those wheels, and the tire would buzz the chainstays in the corners. I'm sure the wider SS hub helps minimize flex.


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## hardmtnbiker (Feb 22, 2005)

I'm curious about the new P321 hub with magnetic pawls. I'm contemplating whether I want to get one for my Seven or just wait and use the Boost148 SS version on a new SS frame.


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## coke (Jun 7, 2008)

hardmtnbiker said:


> I'm curious about the new P321 hub with magnetic pawls. I'm contemplating whether I want to get one for my Seven or just wait and use the Boost148 SS version on a new SS frame.


Currently on the wait list for this bike, but it should be done in August. When it gets here, I'll be able to compare the new magnetic hubs with what I already have. Onyx, old p321 with i9 internals, and dt with 54t. Onyx are by far my favorite and I like them more than anything I've ever ridden, but I decided not to use them on this build due to the weight.

This is what I expect:

Drag - Expect p321 to have slightly more than onyx. On a stand, the onyx rear rolls about as smooth as a front hub and it does seem to make a difference on the trails. The old p321 were very draggy, but from the videos I've seen online, the new design seems to roll a LOT smoother.

Noise - Onyx are totally silent. From what I've seen online, p321 make some noise, but it doesn't seem like it will be audible while riding.

Engagement. - Onyx are instant. The only lag I experience is when the slack is being taken up in my chain. The new p321 design has 216 points. I'll miss the instant engagement, but 216 will be enough.

Weight - Onyx 504.6g. P321 291.4g

While looking up those hub weights, I came across this https://onyxrp.com/store/specialty/dh-iso-hg-157-12mm-thru-2/ It only weighs 413.9. Don't remember seeing that when I was deciding on my wheel build. I may have still gone with p321, but the weight savings over their normal hub would have made it a much more difficult choice.


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