Modern Geo Talk: Chainstays, Stack, Reach, and Bitching About It

Big Bird
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5/27/2026 8:42am

Just a check in to (Probably.) piss some people off. I'm updating my old home made 26" DH bike to take 27.5" wheels. It's got 9.5" travel and the chain stays are growing from 16.5" to a whopping 17.25"! I know. They're getting kind of long, but I had to add 3/4" to fit those huge wheels.

Eae903
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5/27/2026 9:31am
Big Bird wrote:
Just a check in to (Probably.) piss some people off. I'm updating my old home made 26" DH bike to take 27.5" wheels. It's got 9.5"...

Just a check in to (Probably.) piss some people off. I'm updating my old home made 26" DH bike to take 27.5" wheels. It's got 9.5" travel and the chain stays are growing from 16.5" to a whopping 17.25"! I know. They're getting kind of long, but I had to add 3/4" to fit those huge wheels.

I mean, you're a traitor, but at least you didn't talk about fc/rc ratio 

2
ntm95
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5/27/2026 11:00am
I listened to the episode and found it interesting. I have to wonder if some of it is that taller riders are just historically used to...

I listened to the episode and found it interesting. I have to wonder if some of it is that taller riders are just historically used to bikes with shorter RCs so that’s what test riders end up preferring. Santa Cruz also talked about changes they make when making a bike for taller or shorter riders on their Tallboy episode of The Roller Door and while they didn’t go into detail as much as the Spot discussion, the takeaway was kinda the same that shorter riders preferred longer RCs and taller riders preferred shorter RCs

Taller riders historically getting the shaft with the one size fits all chainstay approach, has been my experience.

It takes time to adapt to a longer rear end and riding through your feet and hips. The longer you've been on a short rear end, the longer it takes to recalibrate ones riding style, but the benefits are certainly there afterwards. There's just a weird in between period that makes you think short rear ends aren't so bad.

 

4
5/27/2026 12:19pm
I listened to the episode and found it interesting. I have to wonder if some of it is that taller riders are just historically used to...

I listened to the episode and found it interesting. I have to wonder if some of it is that taller riders are just historically used to bikes with shorter RCs so that’s what test riders end up preferring. Santa Cruz also talked about changes they make when making a bike for taller or shorter riders on their Tallboy episode of The Roller Door and while they didn’t go into detail as much as the Spot discussion, the takeaway was kinda the same that shorter riders preferred longer RCs and taller riders preferred shorter RCs

ntm95 wrote:
Taller riders historically getting the shaft with the one size fits all chainstay approach, has been my experience.It takes time to adapt to a longer rear...

Taller riders historically getting the shaft with the one size fits all chainstay approach, has been my experience.

It takes time to adapt to a longer rear end and riding through your feet and hips. The longer you've been on a short rear end, the longer it takes to recalibrate ones riding style, but the benefits are certainly there afterwards. There's just a weird in between period that makes you think short rear ends aren't so bad.

 

Yeah, that’s why Im wondering if theres selection bias as test riders as a population are likely to have been riding for a long time.

codahale
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5/27/2026 2:26pm
Big Bird wrote:
Just a check in to (Probably.) piss some people off. I'm updating my old home made 26" DH bike to take 27.5" wheels. It's got 9.5"...

Just a check in to (Probably.) piss some people off. I'm updating my old home made 26" DH bike to take 27.5" wheels. It's got 9.5" travel and the chain stays are growing from 16.5" to a whopping 17.25"! I know. They're getting kind of long, but I had to add 3/4" to fit those huge wheels.

Nah, that’s AI

1
codahale
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5/27/2026 2:30pm

Yeah, that’s why Im wondering if theres selection bias as test riders as a population are likely to have been riding for a long time.

I think it’s also probably taller riders hitting the limits on wheelbase. If the brand is committed to long reaches already, they might only be testing an XL front triangle with a long mule rear triangle, and the thing the test riders are reacting to is that the wheelbase is way longer than they like. I think the inverse of this is when brands started doing long reaches, all the tall riders (including me) loved that because all of a sudden the wheelbase was more proportional to the rider height and I didn’t feel like a circus bear as much.

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BlueSpruce
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5/27/2026 4:27pm
codahale wrote:
I think it’s also probably taller riders hitting the limits on wheelbase. If the brand is committed to long reaches already, they might only be testing...

I think it’s also probably taller riders hitting the limits on wheelbase. If the brand is committed to long reaches already, they might only be testing an XL front triangle with a long mule rear triangle, and the thing the test riders are reacting to is that the wheelbase is way longer than they like. I think the inverse of this is when brands started doing long reaches, all the tall riders (including me) loved that because all of a sudden the wheelbase was more proportional to the rider height and I didn’t feel like a circus bear as much.

Theoretically yes but I don't think that's what's happening with most brands. I think I mentioned this before but I had a XXL Hightower V3 and that bike felt so long and cumbersome. Felt like the front wheel was in a different zip code. My new XL Crafty has nearly identical front triangle geo but fits perfect and feels much easier to maneuver. Instead of the front wanting to push wide in every corner, it hooks up and carves the corner. It's counterintuitive but when the F:R gets way out of wack, the short chainsay  actually makes the bike feel longer and more cumbersome. 

 

If I wanted something more nimble than my Crafty I'd go for something with a steeper HTA and shorter front center then you can reduce the rear center a bit. Keep the F:R balanced. This will be so much more effective at reducing the size and "size feel" of the bike rather than just shortening the chainstay. For me the bike has to be balanced period.

3
codahale
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5/27/2026 6:57pm
BlueSpruce wrote:
Theoretically yes but I don't think that's what's happening with most brands. I think I mentioned this before but I had a XXL Hightower V3 and...

Theoretically yes but I don't think that's what's happening with most brands. I think I mentioned this before but I had a XXL Hightower V3 and that bike felt so long and cumbersome. Felt like the front wheel was in a different zip code. My new XL Crafty has nearly identical front triangle geo but fits perfect and feels much easier to maneuver. Instead of the front wanting to push wide in every corner, it hooks up and carves the corner. It's counterintuitive but when the F:R gets way out of wack, the short chainsay  actually makes the bike feel longer and more cumbersome. 

 

If I wanted something more nimble than my Crafty I'd go for something with a steeper HTA and shorter front center then you can reduce the rear center a bit. Keep the F:R balanced. This will be so much more effective at reducing the size and "size feel" of the bike rather than just shortening the chainstay. For me the bike has to be balanced period.

For sure -- I’ve owned a series of XXL Santa Cruz bikes and know exactly the front wheel feeling you’re talking about. You turn as gently as you can, twist your hips to the outside, lean the bike, weight your outside foot, and the front wheel goes “aight imma head out” and you go teeth-first into the center point of the turn.

I think an under-discussed aspect of a long front center is how it changes the spatial relationship between your center of mass and the front contact patch. When you lean a bike, you’re limited in how far to one side you can shift your weight: you’re only as tall as you are tall and too much lean and you’ll clip a pedal. The longer the front end is, the more acute the angle between your center of mass and the front contact patch, which means the reaction force keeping the moment arm of your body at net zero torque (i.e., you’re not just falling over to one side) is on a tangent to the arc of the turn, which is to say, doing more to push you wide than to rail the turn. The part of this I haven’t done as much thinking about is the role of the rear contact patch in a turn. Anyway, I’m over my high school trig/physics quota for the day.

2
BlueSpruce
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5/27/2026 7:51pm
codahale wrote:
For sure -- I’ve owned a series of XXL Santa Cruz bikes and know exactly the front wheel feeling you’re talking about. You turn as gently...

For sure -- I’ve owned a series of XXL Santa Cruz bikes and know exactly the front wheel feeling you’re talking about. You turn as gently as you can, twist your hips to the outside, lean the bike, weight your outside foot, and the front wheel goes “aight imma head out” and you go teeth-first into the center point of the turn.

I think an under-discussed aspect of a long front center is how it changes the spatial relationship between your center of mass and the front contact patch. When you lean a bike, you’re limited in how far to one side you can shift your weight: you’re only as tall as you are tall and too much lean and you’ll clip a pedal. The longer the front end is, the more acute the angle between your center of mass and the front contact patch, which means the reaction force keeping the moment arm of your body at net zero torque (i.e., you’re not just falling over to one side) is on a tangent to the arc of the turn, which is to say, doing more to push you wide than to rail the turn. The part of this I haven’t done as much thinking about is the role of the rear contact patch in a turn. Anyway, I’m over my high school trig/physics quota for the day.

The interesting thing is that the differences are apparent at both slower and faster speeds. Where you are positioned between the wheels makes a much larger impact than a few millimeters difference in total wheelbase. The difference in F:R ratio is surprisingly important in tight switchbacks, tech climbing, etc. The longer Crafty feels more maneuverable even in the slow tight stuff. 

 

An extreme example is if you've ever owned a BMX bike with rear pegs and have rode around standing on the pegs - the front end pushes wide at any speed and you have to lean on the bars to have any weight on the front wheel. It makes the bike feel way longer and cumbersome despite the wheelbase not changing. 

4
sethimus
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5/27/2026 10:45pm Edited Date/Time 5/27/2026 10:46pm
codahale wrote:
I think it’s also probably taller riders hitting the limits on wheelbase. If the brand is committed to long reaches already, they might only be testing...

I think it’s also probably taller riders hitting the limits on wheelbase. If the brand is committed to long reaches already, they might only be testing an XL front triangle with a long mule rear triangle, and the thing the test riders are reacting to is that the wheelbase is way longer than they like. I think the inverse of this is when brands started doing long reaches, all the tall riders (including me) loved that because all of a sudden the wheelbase was more proportional to the rider height and I didn’t feel like a circus bear as much.

forbidden bikes have similar wheelbases than their competitors with short chainstays

they increase cs and stack but reduce reach

2
Primoz
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5/27/2026 11:28pm Edited Date/Time 5/27/2026 11:30pm

Just got through the Spot podcast and... Am I the only one that heard more or less an hour of serving koolaid? 

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codahale
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5/28/2026 6:33am
sethimus wrote:

forbidden bikes have similar wheelbases than their competitors with short chainstays

they increase cs and stack but reduce reach

Yeah, my Mistress has almost exactly the same wheelbase as an XXL Hightower. Folks attribute a lot of dynamics to a long reach that I think are actually the result of a long wheelbase. But there’s a feedback loop in the market, where brands’ marketing sells the stability and capability of a long wheelbase via the specific design choice they used to achieve that -- a long reach -- and then that becomes part of what shop staff and informed buyers start looking for specifically. I know I absolutely would not have bought a bike with a 460mm reach off the rack, but it turns out it totally fits.

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sethimus
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5/28/2026 9:22am Edited Date/Time 5/28/2026 9:24am
codahale wrote:
Yeah, my Mistress has almost exactly the same wheelbase as an XXL Hightower. Folks attribute a lot of dynamics to a long reach that I think...

Yeah, my Mistress has almost exactly the same wheelbase as an XXL Hightower. Folks attribute a lot of dynamics to a long reach that I think are actually the result of a long wheelbase. But there’s a feedback loop in the market, where brands’ marketing sells the stability and capability of a long wheelbase via the specific design choice they used to achieve that -- a long reach -- and then that becomes part of what shop staff and informed buyers start looking for specifically. I know I absolutely would not have bought a bike with a 460mm reach off the rack, but it turns out it totally fits.

knowing what i know now i hate myself for not trying the banshee titan with the long drop outs when i had it

imho banshee had it figured out before everyone else.

will fit the longer cs on my velduro asap when they are available 

Big Bird
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5/28/2026 10:29am
codahale wrote:

Nah, that’s AI

Why would you say that? AI can suck-it. I'm not at all a fan of AI.

codahale
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5/28/2026 12:10pm
codahale wrote:

Nah, that’s AI

Big Bird wrote:

Why would you say that? AI can suck-it. I'm not at all a fan of AI.

Just a stupid joke about the impossibility of enjoying a bike without long chainstays

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Big Bird
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5/28/2026 12:38pm
codahale wrote:

Just a stupid joke about the impossibility of enjoying a bike without long chainstays

Ah. I've been doing it for years. Luckily the bike is going to an old trials riding friend and his son. So the short stays aren't a problem.

BlueSpruce
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5/29/2026 6:49am
codahale wrote:
Yeah, my Mistress has almost exactly the same wheelbase as an XXL Hightower. Folks attribute a lot of dynamics to a long reach that I think...

Yeah, my Mistress has almost exactly the same wheelbase as an XXL Hightower. Folks attribute a lot of dynamics to a long reach that I think are actually the result of a long wheelbase. But there’s a feedback loop in the market, where brands’ marketing sells the stability and capability of a long wheelbase via the specific design choice they used to achieve that -- a long reach -- and then that becomes part of what shop staff and informed buyers start looking for specifically. I know I absolutely would not have bought a bike with a 460mm reach off the rack, but it turns out it totally fits.

Have you ridden a newer XXL Hightower?

codahale
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5/29/2026 6:59am
BlueSpruce wrote:

Have you ridden a newer XXL Hightower?

Nope. Had one on order but cancelled it after riding the Mistress. I have owned two Megatowers and a Tallboy, though, all in XXL.

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Suns_PSD
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5/29/2026 7:21am
sethimus wrote:
knowing what i know now i hate myself for not trying the banshee titan with the long drop outs when i had itimho banshee had it...

knowing what i know now i hate myself for not trying the banshee titan with the long drop outs when i had it

imho banshee had it figured out before everyone else.

will fit the longer cs on my velduro asap when they are available 

Have you detected an issue with the chainstay length on your new Rogue? Are you on a L or XL?

snowsnakes
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5/29/2026 7:31pm
sethimus wrote:

forbidden bikes have similar wheelbases than their competitors with short chainstays

they increase cs and stack but reduce reach

codahale wrote:
Yeah, my Mistress has almost exactly the same wheelbase as an XXL Hightower. Folks attribute a lot of dynamics to a long reach that I think...

Yeah, my Mistress has almost exactly the same wheelbase as an XXL Hightower. Folks attribute a lot of dynamics to a long reach that I think are actually the result of a long wheelbase. But there’s a feedback loop in the market, where brands’ marketing sells the stability and capability of a long wheelbase via the specific design choice they used to achieve that -- a long reach -- and then that becomes part of what shop staff and informed buyers start looking for specifically. I know I absolutely would not have bought a bike with a 460mm reach off the rack, but it turns out it totally fits.

That’s kinda why I’m thinking the S3 forbidden Reya might be more my size than the S4. 475 reach is 5-10mm short of what I typically go for, but the S4 seems like it might start to get a bit cumbersome if I end up stretched towards the front. 

JVP
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6/3/2026 1:11pm

What do people like for sizing on a fun park/DH bike like the new Norco Torrent or Transition TR11 compared to trail/enduro bikes?

I haven't owned a bike with a dual crown in quite a few years. My sweet spot for a 160/170 bike is 500 reach and 64 head angle. Downsize the DH bike a little on reach or keep it the same as the pedal bike? Whistler laps, shuttling certain steep loamy spots, plenty of tech but still fun on Aline, no racing.

1
gibbon
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6/3/2026 2:20pm
codahale wrote:

Nah, that’s AI

Big Bird wrote:

Why would you say that? AI can suck-it. I'm not at all a fan of AI.

That is exactly what an Ai would say...................

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Eae903
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6/3/2026 2:37pm
JVP wrote:
What do people like for sizing on a fun park/DH bike like the new Norco Torrent or Transition TR11 compared to trail/enduro bikes?I haven't owned a...

What do people like for sizing on a fun park/DH bike like the new Norco Torrent or Transition TR11 compared to trail/enduro bikes?

I haven't owned a bike with a dual crown in quite a few years. My sweet spot for a 160/170 bike is 500 reach and 64 head angle. Downsize the DH bike a little on reach or keep it the same as the pedal bike? Whistler laps, shuttling certain steep loamy spots, plenty of tech but still fun on Aline, no racing.

Little shorter on reach, little higher on stack, little shorter cs

paddydigital
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6/3/2026 10:07pm
JVP wrote:
What do people like for sizing on a fun park/DH bike like the new Norco Torrent or Transition TR11 compared to trail/enduro bikes?I haven't owned a...

What do people like for sizing on a fun park/DH bike like the new Norco Torrent or Transition TR11 compared to trail/enduro bikes?

I haven't owned a bike with a dual crown in quite a few years. My sweet spot for a 160/170 bike is 500 reach and 64 head angle. Downsize the DH bike a little on reach or keep it the same as the pedal bike? Whistler laps, shuttling certain steep loamy spots, plenty of tech but still fun on Aline, no racing.

I like the bar height and total reach to be pretty similar so the fit/riding position feels the same between bikes. Then, ideally, pair that with longer stays and slacker HTA on the dh bike to get slacker and longer while preserving front-rear balance. 
 

That being said, as long as the fit is relatively close you don’t need to overthink it. You’re gonna be having way too much fun on Aline to wonder if your reach is 10mm too short. 

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seanfisseli
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6/4/2026 12:10am

I came back to check in and let everybody know that I figured out what flickable means. I am pretty sure that it means something like the feeling of standing on the rear pegs of a BMX bike and feeling the whole front end sort of flick around the pivot point of the rear wheel. Of course, on a mountain bike, we don’t have pegs, but if we have short chainstays the flickable feeling comes from the phenomenon of turning the bars and feeling the whole front end flick around, pivoting around the back end of the bike.


 I think that this added responsiveness at the bars is something that a lot of riders like. Especially if those riders are hunched over and putting weight on the front of their bike (a body position adapted to make up for lack of front end grip/bikes with too low of stack…) It would follow that you would want more responsiveness since you are sort of hindering that front end from coming around with your weight. If you were to put that rider on a bike with a more balanced ratio, they might feel like the front end isn’t as responsive because now there is too much weight on the bars, and the payment point has moved forward and so the bars aren’t having as big of an impact on the turning.

I think this is the reason that we have such massive arguments about chainstay length and handling. The people who are looking for a more responsive feeling at the handlebars are not going to like a long chain stay bikes. And people who want a bike that steers better through the feet are going to hate short chain stay bikes. 

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AgrAde
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1 day ago

lmao

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Primoz
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1 day ago Edited Date/Time 1 day ago

Flickable means its responsive to inputs and changes direction (rotates) quickly without too much effort. It doesn't mean unstable though as it still gives you the confidence to lean on it aggressively. 

Front end turning while standing on rear pegs is probably the opposite of what Flickable is...

That's how I see it. The term is used for bikes and cars. And it usually means you throw it in a corner, aggressively, it will hook up, rotate and won't spit you off. 

Based on that it doesn't have an relation with one geometry value, it has more to do with balance and grip levels to handle the energy of inputs. 

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seanfisseli
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1 day ago
Primoz wrote:
Flickable means its responsive to inputs and changes direction (rotates) quickly without too much effort. It doesn't mean unstable though as it still gives you the...

Flickable means its responsive to inputs and changes direction (rotates) quickly without too much effort. It doesn't mean unstable though as it still gives you the confidence to lean on it aggressively. 

Front end turning while standing on rear pegs is probably the opposite of what Flickable is...

That's how I see it. The term is used for bikes and cars. And it usually means you throw it in a corner, aggressively, it will hook up, rotate and won't spit you off. 

Based on that it doesn't have an relation with one geometry value, it has more to do with balance and grip levels to handle the energy of inputs. 

I’m just trying to decode the people saying that making chainstays longer makes a bike less flickable. 

1
1 day ago
I came back to check in and let everybody know that I figured out what flickable means. I am pretty sure that it means something like...

I came back to check in and let everybody know that I figured out what flickable means. I am pretty sure that it means something like the feeling of standing on the rear pegs of a BMX bike and feeling the whole front end sort of flick around the pivot point of the rear wheel. Of course, on a mountain bike, we don’t have pegs, but if we have short chainstays the flickable feeling comes from the phenomenon of turning the bars and feeling the whole front end flick around, pivoting around the back end of the bike.


 I think that this added responsiveness at the bars is something that a lot of riders like. Especially if those riders are hunched over and putting weight on the front of their bike (a body position adapted to make up for lack of front end grip/bikes with too low of stack…) It would follow that you would want more responsiveness since you are sort of hindering that front end from coming around with your weight. If you were to put that rider on a bike with a more balanced ratio, they might feel like the front end isn’t as responsive because now there is too much weight on the bars, and the payment point has moved forward and so the bars aren’t having as big of an impact on the turning.

I think this is the reason that we have such massive arguments about chainstay length and handling. The people who are looking for a more responsive feeling at the handlebars are not going to like a long chain stay bikes. And people who want a bike that steers better through the feet are going to hate short chain stay bikes. 

That is literally the exact opposite of flickable. 

Also long chainstays doesn’t give you more leverage over your rear wheel, the opposite is true. 

Also, long chainstays ftw

seanfisseli
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1 day ago
I came back to check in and let everybody know that I figured out what flickable means. I am pretty sure that it means something like...

I came back to check in and let everybody know that I figured out what flickable means. I am pretty sure that it means something like the feeling of standing on the rear pegs of a BMX bike and feeling the whole front end sort of flick around the pivot point of the rear wheel. Of course, on a mountain bike, we don’t have pegs, but if we have short chainstays the flickable feeling comes from the phenomenon of turning the bars and feeling the whole front end flick around, pivoting around the back end of the bike.


 I think that this added responsiveness at the bars is something that a lot of riders like. Especially if those riders are hunched over and putting weight on the front of their bike (a body position adapted to make up for lack of front end grip/bikes with too low of stack…) It would follow that you would want more responsiveness since you are sort of hindering that front end from coming around with your weight. If you were to put that rider on a bike with a more balanced ratio, they might feel like the front end isn’t as responsive because now there is too much weight on the bars, and the payment point has moved forward and so the bars aren’t having as big of an impact on the turning.

I think this is the reason that we have such massive arguments about chainstay length and handling. The people who are looking for a more responsive feeling at the handlebars are not going to like a long chain stay bikes. And people who want a bike that steers better through the feet are going to hate short chain stay bikes. 

That is literally the exact opposite of flickable. 

Also long chainstays doesn’t give you more leverage over your rear wheel, the opposite is true. 

Also, long chainstays ftw

I’m just trying to figure out what they’re flicking. Any clues?

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