# Stack height



## NWA_Tre (Sep 30, 2021)

TLDR: What stack height do you like, and why? Are stacks measured consistently across manufacturers?

I searched this topic and primarily found convo's from 4 years ago. Much has changed in geo since then, so I wanted to get some updated opinions. I found this thread on VitalMTB that's semi-recent, and everyone basically disagrees on the topic whilst also disagreeing on how comparable Motocross was to MTB in this regard...

I have a spreadsheet of bikes I'm interested in with all of the geo measurements. I also have bikes I've ridden (rode?) on the sheet so I can start to formulate what I think I like and don't like, similarities, differences, etc. The state of buying bikes these days has forced this sort of approach. Dealers don't have bikes to sit on, and a few of these bikes aren't even offered around me anyway.

I've spent time obsessing over certain measurements, but typically only when they stand out with all else mostly equal. One such measurement is stack height. Most of the bikes I'm looking at have somewhat comparable stack heights, within 20mm of one another. Close enough that you could use spacers or bars to make them even. However sometimes I come across a bike that has a stack that's WAY different.

One such example is the Esker Japhy, which lists a 614 stack height (size Large). Now, Esker says on their geo chart that their numbers are at 30% sag, so that number is likely a little taller at static height, but still...This also calls into question if all manufacturers measure stack the same way? I emailed Esker on the subject and their response started out like this:

"Take your fork A-C and add the head tube length to get stack height."

That's not at all how stack height has been explained to me before. What I expect stack height to mean is the vertical distance from the bottom bracket plane to the head tube plane (top of HT). Now, if I do some triangle calculations, I come up closer to the 650's with the Marzocchi fork the Japhy build is spec'd with.

So I pressed Esker (reply actually came from Krueger Outdoors?) further and they said, "Just talked to our tech guy who said stack is the distance from the tire tread (assuming he means contact patch?) to the top of the steerer stem cap. I just measured my J1 Large and came up with 44.5 inches."

Again, not accurate from what I have seen. When I do this calc (taking off tire radius and assumed extra steerer length above top of HT) I again come out at a more typical stack compared to other bikes.

So we have a number of items here:

Low/High/Rider specific stack height...implications on handling (first) and comfort (second). TLDR: old guys want high bars, young guys disagree but many want low bars.
Is stack measured consistently across manufacturers?
What the Helsinki is the dang stack height of the Esker Japhy, in terms that are comparable to other models?!?


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## Hexsense (Aug 10, 2021)

Answer the TLDR,
My preferred stack for 5'6.5 rider:
road: 520mm, -17 degree stem. I stay in drop 40% of the time. Drop is 125mm lower than bar top.
gravel: 540mm, -6 degree stem. Drop of gravel bike is about half way between top and drop of road bike. And it's top is tall and comfy.
29er MTB: lowest possible given the fork height. It's never low enough. For example, if the bike has 600mm stack then I have to use -25 degree stem, or maybe Syntace Drop Force, or some -30 degree stem. MTB riding position is quite dynamic so I'm not quite precise in measuring it correctly with sag. All I know is, I can't get low enough using flat bar unless I got to around 560mm stack. Which is not seen on 29" wheel MTB with suspension fork.


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## NWA_Tre (Sep 30, 2021)

Hexsense said:


> 29er MTB: lowest possible given the fork height. It's never low enough...All I know is, I can't get low enough using flat bar unless I got to around 560mm stack. Which is not seen on 29" wheel MTB with suspension fork.


Curious, do you feel this has to do with front wheel handling/traction?


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## Hexsense (Aug 10, 2021)

No, just proper ergonomics with RAAD around 56 degree. I have long torso for my height and use quite low saddle height. My low-ish stack height doesn't look impressive anymore when consider as saddle to bar drop. Low saddle, then the bar have to be low too.
See, on road, stack scale with frame size. But on MTB, it's already too tall with smallest sizes. But then become a bit too low on large,XL (which require raiser bar etc.).
I trained from road and only pedal well with my torso lean a bit forward. That make my shoulder socket lowered, and thus if the bar is high, then I have to bend the elbow a lot to keep my torso where I want and my hand on the bar.


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## NWA_Tre (Sep 30, 2021)

Hexsense said:


> No, just proper ergonomics with RAAD around 56 degree. I have long torso for my height and use quite low saddle height. My low-ish stack height doesn't look impressive anymore when consider as saddle to bar drop. Low saddle, then the bar have to be low too.
> See, on road, stack scale with frame size. But on MTB, it's already too tall with smallest sizes. But then become a bit too low on large,XL (which require raiser bar etc.).
> I trained from road and only pedal well with my torso lean a bit forward. That make my shoulder socket lowered, and thus if the bar is high, then I have to bend the elbow a lot to keep my torso where I want and my hand on the bar.


when seated pedaling on flat ground are your hands weighting the bars? In other words heavy hands? My current bike (likely too large) feels that way and it's painful on flat, semi-smooth courses. I'm fine on descents (out of saddle) and in/out of saddle climbs, though. Still, since I may end up ordering my next bike without the luxury of getting to try it first (due to bike shortages), I'd like to have an idea on stack height.


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## looks easy from here (Apr 16, 2019)

I'm 6' with a +2 ape index. I like tall stack. IIRC my bike has a stack of 624mm, with 6mm of spacers and bars with 38mm of rise. Though I suspect part of my preference is affected by flexibility, core strength and confidence to lean forward to attack downhills that could all use some improvement.


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## NWA_Tre (Sep 30, 2021)

looks easy from here said:


> I'm 6' with a +2 ape index. I like tall stack. IIRC my bike has a stack of 624mm, with 6mm of spacers and bars with 38mm of rise. Though I suspect part of my preference is affected by flexibility, core strength and confidence to lean forward to attack downhills that could all use some improvement.


I'm about the same ape as you. What's your inseam, if you don't mind me asking, haha? Mine is 32". Are you heavy handed seated on flat ground?


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## Hexsense (Aug 10, 2021)

NWA_Tre said:


> when seated pedaling on flat ground are your hands weighting the bars? In other words heavy hands? My current bike (likely too large) feels that way and it's painful on flat, semi-smooth courses. I'm fine on descents (out of saddle) and in/out of saddle climbs, though. Still, since I may end up ordering my next bike without the luxury of getting to try it first (due to bike shortages), I'd like to have an idea on stack height.


Most people think low stack alway cause weight on the hands. That's true if lowered bar force your torso to lean at a steeper angle.
In my case, it's opposite. My torso want to lean at a certain angle regardless of the bar height. If the bar is too high, I bend elbow and rest too much weight with my hand. But if the bar height is lowered, then I use less hand support and more of core muscle support. So, for me, tall bar cause heavy hands. Low enough bar (just right, not too low that it force me to lean more than I want) reduce weight from my hands.

To combat weight on hands, I might try to pull saddle more rearward on your current bike first though.


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## NWA_Tre (Sep 30, 2021)

Hexsense said:


> Most people think low stack alway cause weight on the hands. That's true if lowered bar force your torso to lean at a steeper angle.
> In my case, it's opposite. My torso want to lean at a certain angle regardless of the bar height. If the bar is too high, I bend elbow and rest too much weight with my hand. But if the bar height is lowered, then I use less hand support and more of core muscle support. So, for me, tall bar cause heavy hands. Low enough bar (just right, not too low that it force me to lean more than I want) reduce weight from my hands.


it's an interesting point. And I probably do need to work on my core. To be clear, I'm heavy on the hands only seated on flat ground. I saw another member say the same but that they got used to it because in every other situation they felt good. Wondering if that's my fate as well.


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## looks easy from here (Apr 16, 2019)

NWA_Tre said:


> I'm about the same ape as you. What's your inseam, if you don't mind me asking, haha? Mine is 32". Are you heavy handed seated on flat ground?


I'm about a 32, also. No, I'm pretty upright and my hands are pretty light on the bars on flat ground.


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## NWA_Tre (Sep 30, 2021)

looks easy from here said:


> I'm about a 32, also. No, I'm pretty upright and my hands are pretty light on the bars on flat ground.


You ride a Large or XL? Thanks for playing 20 questions 😆


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## looks easy from here (Apr 16, 2019)

Large/19" 2017 Jamis DragonSlayer. It has a short reach (426mm) but slightly longish ett (~630mm?). I have a 60mm stem and 780mm bars. But I also have a -2° Works Components angleset, which drops the front end a bit, and a 10mm Reverse Angle spacer in place of the crownrace, which raises it back up a little.

Back on the topic of stem and bars, they also affect how you load your hands. Wider bars pull you forward, shorter stems let you sit back. My bike came with 720mm flat bars and an 80mm stem which I ran for about 6 months. Then I put 800/20mm risers and the 60mm stem on, also for about 6 months, but they still felt too low, and I was unsure about the width. Finally I put on the 780/38mm risers (still with the 60mm stem) and it feels perfect.


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## NWA_Tre (Sep 30, 2021)

looks easy from here said:


> Large/19" 2017 Jamis DragonSlayer. It has a short reach (426mm) but slightly longish ett (~630mm?). I have a 60mm stem and 780mm bars. But I also have a -2° Works Components angleset, which drops the front end a bit, and a 10mm Reverse Angle spacer in place of the crownrace, which raises it back up a little.


My bike is a Fuji Nevada 1.7 XL. 459 reach, 653 ETT, 635 stack (at 69* HTA, 73* STA). I have a 40mm stem and 780 bars with 25mm rise. I started with 60mm stem and flat bars with just a little backsweep. My stem is all the way up, probably 25mm spacers.


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## NWA_Tre (Sep 30, 2021)

Doing the math on the Japhy, I think the 614 stack is at 30% fork sag - which Esker has a little note at the bottom of their geo chart that says


> Hardtail geometry based on 30% fork sag.


Actual stack by my rough calculations (size Large) should be more like 645ish. Not horribly low at all 

Wondering if any Japhy owners can confirm?


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## Fuse6F (Jul 5, 2017)

i find dramatic increase with hand pressure after tipping my seat down.

stack height??? 

the whole bike geometry comes into question i guess. depends on what you want the bike to do? a bike set to 63 degree hta meant for going down the steep gnarly stuff will setup diff than one for general trail riding w 130mm fork. or you should want it to be.


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## NWA_Tre (Sep 30, 2021)

Fuse6F said:


> i find dramatic increase with hand pressure after tipping my seat down.
> 
> stack height???
> 
> the whole bike geometry comes into question i guess. depends on what you want the bike to do? a bike set to 63 degree hta meant for going down the steep gnarly stuff will setup diff than one for general trail riding w 130mm fork. or you should want it to be.


I want an all a rounder. There aren’t many downhill parks here. No lifts. No sustained long runs. Flow, tech, some occasional bike park stuff, maybe a trip to a more DH oriented park every few months. 

Seems like the bike in question doesn’t have a criminally low stack height as I previously thought. They just list all their geo at 30% sag, so it can be odd to see the numbers up next to other manufacturers who don’t.


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## Grinchy8 (Jul 6, 2021)

Is stack always measured to the top of the head tube? So it ignores stem length and steerer height?


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## Fuse6F (Jul 5, 2017)

NWA_Tre said:


> I want an all a rounder. There aren’t many downhill parks here. No lifts. No sustained long runs. Flow, tech, some occasional bike park stuff, maybe a trip to a more DH oriented park every few months.
> 
> Seems like the bike in question doesn’t have a criminally low stack height as I previously thought. They just list all their geo at 30% sag, so it can be odd to see the numbers up next to other manufacturers who don’t.



it makes it hard to compare diff bikes if others dont list the same

assume 64 degree hta unloaded and figure out the stack/opposite length increase by using 36mm for the hypotenuse.


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## looks easy from here (Apr 16, 2019)

Grinchy8 said:


> Is stack always measured to the top of the head tube? So it ignores stem length and steerer height?


Yes. It's strictly a frame measurement. Though it is based on having a fork with a specific axle to crown length.


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## NWA_Tre (Sep 30, 2021)

Grinchy8 said:


> Is stack always measured to the top of the head tube? So it ignores stem length and steerer height?


I believe so, and I think the reasoning is that within the range of Reach, you're not likely to move your body PAST the head tube (ie. super steep seated climbing, jumping, etc.).


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## NWA_Tre (Sep 30, 2021)

Fuse6F said:


> it makes it hard to compare diff bikes if others dont list the same
> 
> assume 64 degree hta unloaded and figure out the stack/opposite length increase by using 36mm for the hypotenuse.


yep, and I come out around 645 on the stack in that case...of course I'm making a few minor assumptions


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## frdfandc (Sep 5, 2007)

NWA_Tre said:


> it's an interesting point. And I probably do need to work on my core. To be clear, I'm heavy on the hands only seated on flat ground. I saw another member say the same but that they got used to it because in every other situation they felt good. Wondering if that's my fate as well.



I'm heavy on the hands when on flat ground as well, but fine when actually riding trails. So I've set my bikes up to fit this. I don't ride flat ground that often on my mountain bike. An occasional rail/trail. Normally I'm on my road bike for this.


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## NWA_Tre (Sep 30, 2021)

Last night I started consciously trying to ride in a more modern position and it went pretty well. I caught myself staying back a few times and noted the traction seemed to be horrible, which was a good reminder to get my head down and forward, and bend my elbows a bit. I honestly used to feel like I was pushing the bike through corners, or riding the back of the bike, praying the front would hold. It feels so much better to push back against the trail, to actively apply weight to the front end when needed. My HTA is 69*, so I have to be really fluid, loose, and ready to absorb things, move around, etc. But I want to get accustomed to this style before going to a more slacked out bike. So far, so good.


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## looks easy from here (Apr 16, 2019)

NWA_Tre said:


> I believe so, and I think the reasoning is that within the range of Reach, you're not likely to move your body PAST the head tube (ie. super steep seated climbing, jumping, etc.).


Nope. It's because it's just a measurement of the _frame's _dimensions, not the _bike's_ dimensions, along with most other geo measurements most manufacturers give (bb height is the one exception that springs to mind; it's dependent on tire diameter). Things like stems, steerer tube length and handlebars can be changed, and can muddle 1:1 comparison.

Though, as I said a couple posts back, all geo is attached to a specific fork atc length.


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## NWA_Tre (Sep 30, 2021)

looks easy from here said:


> Nope. It's because it's just a measurement of the _frame's _dimensions, not the _bike's_ dimensions, along with most other geo measurements most manufacturers give (bb height is the one exception that springs to mind; it's dependent on tire diameter). Things like stems, steerer tube length and handlebars can be changed, and can muddle 1:1 comparison.
> 
> Though, as I said a couple posts back, all geo is attached to a specific fork atc length.


right, I think my point was it almost doesn't make sense to measure stack any other way. As you said, it's a frame measurement, and coming out of the top of the HT is the steerer, which means you can't really use more reach beyond that point. Granted, a long steerer could further limit reach to a degree. I guess I feel geo numbers have to be looked at together, and Stack is appropriately measured in the context of other measurements.


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## frdfandc (Sep 5, 2007)

NWA_Tre said:


> right, I think my point was it almost doesn't make sense to measure stack any other way. As you said, it's a frame measurement, and coming out of the top of the HT is the steerer, which means you can't really use more reach beyond that point. Granted, a long steerer could further limit reach to a degree. I guess I feel geo numbers have to be looked at together, and Stack is appropriately measured in the context of other measurements.


When I did bike fittings, especially when someone was upgrading their bikes, I took 3 major measurements. Floor to top of handlebar, center of HT to nose of saddle, and center of bottom bracket to top of saddle.

With these 3 measurements, I was able to accurately get someone on the correct sized bike with the appropriate fitment (stem/handlebar/seat post swaps if needed). By learning this, I was able to transfer all measurements from one bike to another without much issue and purchase the needed parts for proper fitment.

On my MTB's, it was a straight offset seat post, 90mm stem, flat handlebar, 2 10mm spacers and 1 2.5mm spacer. This was my fit on 3 different bikes from different manufacturers. I was fitted to my road bike by a co-worker (I worked for a shop). We used a system similar to Retul, but used a fit bike that was able to make minute adjustments via a computer, which moved everything around. After the fitting, I made the appropriate changes immediately, with minor tweaks to the stem angle and seat position (fore/aft) over the following 2 months of riding.


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## NWA_Tre (Sep 30, 2021)

ETT is one that I like but I think should be measured with an industry standard. How about two seat positions: X mm from bottom bracket, and Y mm from bottom bracket. Give people some idea where the seat would be relative to that ETT measurement. As it is, nobody knows that seat height the mfr chose in measuring ETT. If I can’t sit on a bike, I need to know how long it’s going to feel seated.


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## frdfandc (Sep 5, 2007)

NWA_Tre said:


> ETT is one that I like but I think should be measured with an industry standard. How about two seat positions: X mm from bottom bracket, and Y mm from bottom bracket. Give people some idea where the seat would be relative to that ETT measurement. As it is, nobody knows that seat height the mfr chose in measuring ETT. If I can’t sit on a bike, I need to know how long it’s going to feel seated.


ETT is only the measurement from the center of the headtube to the center of the seat tube with the seat tube extended. Not where the seat tube physically ends. Add a couple inches to the top of the seat tube. Usually measured with a seat post installed and measurement parallel to the ground.


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## NWA_Tre (Sep 30, 2021)

frdfandc said:


> ETT is only the measurement from the center of the headtube to the center of the seat tube with the seat tube extended. Not where the seat tube physically ends. Add a couple inches to the top of the seat tube. Usually measured with a seat post installed and measurement parallel to the ground.


right, I know in theory how it's supposed to be measured, but the specific point in the seat post where the measurement is taken affects the ETT, as STA is less than 90 and the SP is getting further from the HT on the horizontal plane as you go up the SP. Now, if it's parallel to the ground from the top of the HTA, we have to look at STL to know how far our SP will be extended...but are any mfrs specifying where they took the ETT measurement?


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## frdfandc (Sep 5, 2007)

NWA_Tre said:


> right, I know in theory how it's supposed to be measured, but the specific point in the seat post where the measurement is taken affects the ETT, as STA is less than 90 and the SP is getting further from the HT on the horizontal plane as you go up the SP. Now, if it's parallel to the ground from the top of the HTA, we have to look at STL to know how far our SP will be extended...but are any mfrs specifying where they took the ETT measurement?


Take your tape measure and place it directly on top of the center of the head tube (bare frame). Then measure horizontally to the seat tube. Make sure to keep it level. Now extend the seat tube measurement up towards the seat. Where the seat tube measurement intersects with the tape measure is where the measurement is taken. Most often its about 1.5 to 2.5 inches above where the seat tube physically ends, unless the bike has compact geometry, where the top tube slants excessively down to the seat tube, leaving a large portion of the seat post exposed. Then you would measure straight back to the seat post. That's where the ETT is measured. Every bike is different based on the design of the frame. Some have more exposed seat post, others do not.


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## NWA_Tre (Sep 30, 2021)

frdfandc said:


> Take your tape measure and place it directly on top of the center of the head tube (bare frame). Then measure horizontally to the seat tube. Make sure to keep it level. Now extend the seat tube measurement up towards the seat. Where the seat tube measurement intersects with the tape measure is where the measurement is taken. Most often its about 1.5 to 2.5 inches above where the seat tube physically ends, unless the bike has compact geometry, where the top tube slants excessively down to the seat tube, leaving a large portion of the seat post exposed. Then you would measure straight back to the seat post. That's where the ETT is measured. Every bike is different based on the design of the frame. Some have more exposed seat post, others do not.


I think stack is most helpful in a rider’s true ETT. We all know our seat height above BB. Based on our inseam. Measuring directly from here to the top center of the HT would be most accurate for seated reach


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## NWA_Tre (Sep 30, 2021)

frdfandc said:


> Take your tape measure and place it directly on top of the center of the head tube (bare frame). Then measure horizontally to the seat tube. Make sure to keep it level. Now extend the seat tube measurement up towards the seat. Where the seat tube measurement intersects with the tape measure is where the measurement is taken. Most often its about 1.5 to 2.5 inches above where the seat tube physically ends, unless the bike has compact geometry, where the top tube slants excessively down to the seat tube, leaving a large portion of the seat post exposed. Then you would measure straight back to the seat post. That's where the ETT is measured. Every bike is different based on the design of the frame. Some have more exposed seat post, others do not.


I guess my larger point is that ETT should tell you something. Consumers shouldn't be left to do more geometry calculations in order to see how a given bike compares to their current rig, another new bike, etc. If it's measured from a consistent point, it would. Measuring it from a static height above the BB, along the seat tube/post (in the case of very short seat tubes) would provide better info, but stack height absolutely comes into play as well.


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## frdfandc (Sep 5, 2007)

NWA_Tre said:


> I think stack is most helpful in a rider’s true ETT. We all know our seat height above BB. Based on our inseam. Measuring directly from here to the top center of the HT would be most accurate for seated reach


Well you have frame stack and reach and then you have handlebar stack and reach. Frame stack and reach can only get you so far in choosing a frame. It shouldn't be the definitive answer for selecting a frame. You also have to include stem length and handlebar shape to get final measurements. You have to remember that these measurements work together to get you the proper fit. In all reality you can take 2 different frames with different ETT/stack/reach and make them the same when you're actually riding the bike. Which is what really matters. Actually riding the bike.


Here is a good article on stack/reach and bike fitment when dealing with MTB's









Tech Talk: The importance of stack and reach


Adjusting stack and reach is one of the best ways to tinker with geometry on your bike (click to enlarge). Photo courtesy of Art's Cyclery Editors Note: This article was written by Art's Cyclery web content editor Brett Murphy, who uses his mechanical engineering background to explain the...




www.mtbr.com


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## BansheeRune (Nov 27, 2011)

Grinchy8 said:


> Is stack always measured to the top of the head tube? So it ignores stem length and steerer height?


This method gives a baseline regardless of axle to crown to be used.

Stack is a figure that is a constant.
Stem length and, bar height are all variables that a maker cannot answer since rider choice will change the constant.

That aside, A/C will make a modest tweak to STA/HTA as well as BB height.


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