So other people think short chain stays are stupid too

Posted by: Endur-Bro

Can someone explain how short chainstays climb better?

To climb effectively you need two things:

1) enough traction on the rear wheel to make use of the power available.

2) front wheel stays down so you can steer and don't loop out.

If you have a problem with either ^^^ you don't climb well.

• As you move the rear wheel backwards [longer CS] you are moving it away from the rider's CG [assuming everything else stays the same] so there is less weight on it and that results in less traction. But, that also means more weight on the front wheel.
• Conversely as you move the wheel forwards [shorter CS] you are moving it closer to the rider's CG [assuming everything else stays the same] so there is more weight on it and that results in more traction. But, that also means less weight on the front wheel.
• My body type carries most of its weight in the upper half so my front wheel is easily weighted and it's hard for me to weight the rear wheel. I never loop out on a bike when climbing for example even with very short CS. However, it's really easy for me to spin the rear tire on a bike that doesn't have short CS because that wheel is not close enough to my CG.
• This situation is made worse by longer bikes [moving bars forward] and steeper STAs [moving CG forward].
• One solution is to shorten the CS. Brings the rear wheel closer to CG and improves traction.
• Another solution is to slacken the effective STA such as with an offset seatpost. Moves CG backwards.
• Final solution is to bring bars closer such as with a shorter frame and/or high Stack. Moves CG backwards.
• Not shockingly my bikes combine some or all of these factors because that works for me.

Now this ^^ all relates to the rider's CG. That's why you have a bunch of people saying they climb better with short CS, a bunch who say they climb better with longer CS, and a bunch who don't care about the topic because most bikes just work fine for them. They are all right.

Posted by: Endur-Bro

Can someone explain how short chainstays climb better?

Short is a relative thing. For large bikes bikes where the seat height places the riders centre of mass, which is about belly button area, over the rear tire, the rider will loop out too easily. People talk about weighting the front wheel but a more correct term is keeping the weight ahead of the rear axle. When climbing steep trails we tend to pull back on the bars to counter pedalling forces. We don’t push down. Standing climbing is a bit different. There shorter chainstays may be better.

I think the designers that make the rear centre the same across all sizes are compromising somewhere. They steepen the seat tube angle as a bandaid for too short stays. Then state that it’s more efficient with zero ergonomic data to back that up. So then short guys like me get saddled with shitty seat tube angles and tall riders get the wrong weight distribution with a super long front centre and dinky rear.

I find it odd that people want longer and longer reach and slacker head angle for more stability yet want short stays. Those seem to be opposite things. To me I think the same rear end for all sizes is a cheepniss thing. It’s less costly to make all rear triangles the same. One mold, one size of aluminum tubes to cut and weld, one rear kinematic. If it’s more costly the manufacturer may lose sales. The same rear triangle for all seems to be a vestige of the road bike design foisted on mountain bike design. A better solution might be to maintain the wheelbase of a bike but move the bb forward on larger bikes. Maintain the same front-rear ratio for all sizes. But make them longer of course as the frame size increases.

Posted by: Vikb

Posted by: Endur-Bro

Can someone explain how short chainstays climb better?

That drawing has the centre of mass too far forward. It’s more near the riders belly button.

Imagine if we theorized all the stupid out of mountain biking. How boring would it be.

😂😂

I am obviously an insensitive bastard cuz the cockpit on my last 2 non-custom but dentist-grade expensive bikes has been perfect off the shop floor but I probably don't know what is good for me

I was thinking about it ( on the john ) and I think I can feel more on a long bike

or maybe I feel that i feel more ?

Posted by: XXX_er

I am obviously an insensitive bastard cuz the cockpit on my last 2 non-custom but dentist-grade expensive bikes has been perfect off the shop floor but I probably don't know what is good for me

I was thinking about it ( on the john ) and I think I can feel more on a long bike

or maybe I feel that i feel more ?

https://youtu.be/-iW0FVLd-3M?si=dyX-XyTZeqT98TBq

Posted by: XXX_er

I am obviously an insensitive bastard cuz the cockpit on my last 2 non-custom but dentist-grade expensive bikes has been perfect off the shop floor but I probably don't know what is good for me

I was thinking about it ( on the john ) and I think I can feel more on a long bike

or maybe I feel that i feel more ?

Related...

https://nsmb.com/forum/forum/health-and-fitness-23/topic/the-single-most-important-factor-in-our-health-132998/

IIRC the early short CS 29ers were lauded essentially because they made dual 29ers ride more compactly for <6' people and so they were considered good for everyone at every size. It took another 15 years for manufacturers to realize that different sized people are sized differently and that the same CS for every size rider is lazy design and generally not ideal. And despite that some models should have shorter CS even in bigger sizes depending on the intended use of the bike. But it's mountain biking, always selling the simplest single solution to all the people in all the places doing all the things.

Posted by: Blofeld

This is very exciting! If you’re going custom you could get sliders set up for a 450-470mm chainstay range. I like the sound of that length for an XL-ish bike and a tendency to loop out. Slider options are great if you ever change fork length as well.

I think if your baseline is a 20” Stooge Scrambler the low A2C (and resultant stack) would make it fit very small (for the reach) compared to other hardtails you’d be able to test out. As V mentioned, the slack SA and (presumably) high saddle is going to put your weight pretty far back on the bike, despite the longish CS. Shortening the stem (bars rearward and a bit lower) also may make the front end feel lighter when climbing, so that’s something to consider as well.

I don’t believe that reach is a very good metric for bike sizing. If you’re going to go custom, I’m sure whomever your working with will be able to sort your cockpit dimensions out with whatever value you’d like as a reach number. In terms of steep climbs where the battle is spinning out vs looping out, the main factor should be where your saddle and centre of gravity sit relative to the rear wheel.

I'm riding two bikes regularly, a Surly Ice Cream Truck with an 80mm stem and a Stooge Scrambler with a 100mm stem. Both are susceptible to loop-outs, and with those stem lengths both are pretty close to the same size. The Ice Cream Truck has a bit higher stack with a 140mm fork, but you're right, the Stooge has a colossal spacer stack.

I was thinking sliders as well, maybe 460-480mm?

Posted by: velocipedestrian
I don't think I'll ever get a custom frame, not because I don't like the idea, but the analysis paralysis would preclude me ever committing to a set of numbers.

I'm kind of the opposite - excited to crunch numbers and come up with something original that fits me well.

Posted by: Vikb

Posted by: Endur-Bro

Can someone explain how short chainstays climb better?

To climb effectively you need two things:

1) enough traction on the rear wheel to make use of the power available.

2) front wheel stays down so you can steer and don't loop out.

If you have a problem with either ^^^ you don't climb well.

• As you move the rear wheel backwards [longer CS] you are moving it away from the rider's CG [assuming everything else stays the same] so there is less weight on it and that results in less traction. But, that also means more weight on the front wheel.
• Conversely as you move the wheel forwards [shorter CS] you are moving it closer to the rider's CG [assuming everything else stays the same] so there is more weight on it and that results in more traction. But, that also means less weight on the front wheel.
• My body type carries most of its weight in the upper half so my front wheel is easily weighted and it's hard for me to weight the rear wheel. I never loop out on a bike when climbing for example even with very short CS. However, it's really easy for me to spin the rear tire on a bike that doesn't have short CS because that wheel is not close enough to my CG.
• This situation is made worse by longer bikes [moving bars forward] and steeper STAs [moving CG forward].
• One solution is to shorten the CS. Brings the rear wheel closer to CG and improves traction.
• Another solution is to slacken the effective STA such as with an offset seatpost. Moves CG backwards.
• Final solution is to bring bars closer such as with a shorter frame and/or high Stack. Moves CG backwards.
• Not shockingly my bikes combine some or all of these factors because that works for me.

Now this ^^ all relates to the rider's CG. That's why you have a bunch of people saying they climb better with short CS, a bunch who say they climb better with longer CS, and a bunch who don't care about the topic because most bikes just work fine for them. They are all right.

LOL 😂

I love how the image you chose to prove your point is a marketing image for Aenomaly Constructs Switchgrade; which effectively steepens the STA when climbing.  Notice the saddle tilted down and the lever below the saddle nose? 

By the way; it's a great product.  Been using mine all week on my new: super steep, super slack, 460mm CS, Über-Enduro bike. Which oddly enough is a better tech climber than my Gen 1 Chromag Surface.  ¯\(ツ)/¯

Posted by: Endur-Bro

I love how the image you chose to prove your point 

The image wasn't chosen to prove my point. It's just an illustration regarding weight distribution and CG. If your new bike with long CS climbs well for you that's great. They obviously suit some people. Unfortunately they don't work well for everyone...that was my point.

Posted by: Endur-Bro

I love how the image you chose to prove your point is a marketing image for Aenomaly Constructs Switchgrade; which effectively steepens the STA when climbing. Notice the saddle tilted down and the lever below the saddle nose?

By the way; it's a great product. Been using mine all week on my new: super steep, super slack, 460mm CS, Über-Enduro bike. Which oddly enough is a better tech climber than my Gen 1 Chromag Surface. ¯(ツ)/¯

Ya think you might be taking the image a little too literally? It’s just a drawing showing where center of mass and various forces could be in a relative sense; it really doesn’t need to be super accurate.

Posted by: Vikb

The image wasn't chosen to prove my point. It's just an illustration regarding weight distribution and CG. If your new bike with long CS climbs well for you that's great. They obviously suit some people. Unfortunately they don't work well for everyone...that was my point.

How do you think weight distribution works?