So other people think short chain stays are stupid too

Posted by: Vikb

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.

Isn't a bike ultimately a big lever pivoting on the rear axle? Weight closer to the rear axle has less leverage on the rear axle effectively weighting the whole lever less. Longer chainstays place the weight further forward effectively increasing leverage on the rear axle (traction) and on the front wheel (steering pressure). Any taller rider on a short CS bike will tell you that you get the opposite with a slack seat tube angle that puts you way back. I'm 6'6" and had an Evil Wreckoning with a 74' ESTA and guess what? It sucked. At full extension I was sitting barely forward of the rear axle and the bike had shitty everything. When I switched to a Geometron G1 I was positioned more centrally between the two axles and it climbed comfortably on steep and mellow grades. At my height the requisite WB was massive and caused a different set of problems but as far as climbing balance it was pretty clear that shorter rear center isn't better. Balanced is better.

Posted by: craw

Isn't a bike ultimately a big lever pivoting on the rear axle? Weight closer to the rear axle has less leverage on the rear axle effectively weighting the whole lever less. Longer chainstays place the weight further forward effectively increasing leverage on the rear axle (traction) and on the front wheel (steering pressure). 

That's definitely not correct in terms of how to understand weighting the wheels. You can't add weight to both wheels at once that would make no sense. You've only got a finite amount of weight to share between your contact points with the ground. If you move your CG between the wheels you are putting more weight on the wheel you move the CG towards. As I mentioned above that can be achieved a number of ways [CS length, STA, front centre, etc...]. There is no lever effect in play as far as weighting wheels goes. 

All that said I'm not suggesting short/shorter CS are a good solution for everyone. In fact that's exactly opposite of what I am saying. So if short CS and slacker STAs don't work for you I get it and I am glad you found a geo that gives you what you want from your bike. Just keep in mind that because you find it awesome that doesn't mean that somebody else [like me] might find it terrible.

Posted by: craw

Isn't a bike ultimately a big lever pivoting on the rear axle? Weight closer to the rear axle has less leverage on the rear axle effectively weighting the whole lever less. Longer chainstays place the weight further forward effectively increasing leverage on the rear axle (traction) and on the front wheel (steering pressure). Any taller rider on a short CS bike will tell you that you get the opposite with a slack seat tube angle that puts you way back. I'm 6'6" and had an Evil Wreckoning with a 74' ESTA and guess what? It sucked. At full extension I was sitting barely forward of the rear axle and the bike had shitty everything. When I switched to a Geometron G1 I was positioned more centrally between the two axles and it climbed comfortably on steep and mellow grades. At my height the requisite WB was massive and caused a different set of problems but as far as climbing balance it was pretty clear that shorter rear center isn't better. Balanced is better.

Wild that until you got your G1 that had you and andy been on the same bike model, both of you would've been riding bikes with the same CS length.

It was always wild seeing yourself and other tall riders bikes with the saddle almost above the rear axle.  Even in whats likely the average biker height range The Wreckoning ST/STA appeared wack.

Posted by: Vikb

Posted by: craw

Isn't a bike ultimately a big lever pivoting on the rear axle? Weight closer to the rear axle has less leverage on the rear axle effectively weighting the whole lever less. Longer chainstays place the weight further forward effectively increasing leverage on the rear axle (traction) and on the front wheel (steering pressure). 

That's definitely not correct in terms of how to understand weighting the wheels. You can't add weight to both wheels at once that would make no sense. You've only got a finite amount of weight to share between your contact points with the ground. If you move your CG between the wheels you are putting more weight on the wheel you move the CG towards. As I mentioned above that can be achieved a number of ways [CS length, STA, front centre, etc...]. There is no lever effect in play as far as weighting wheels goes. 

All that said I'm not suggesting short/shorter CS are a good solution for everyone. In fact that's exactly opposite of what I am saying. So if short CS and slacker STAs don't work for you I get it and I am glad you found a geo that gives you what you want from your bike. Just keep in mind that because you find it awesome that doesn't mean that somebody else [like me] might find it terrible.

Ya having given it more thought I'm in agreement with this. I think I was trying to work in/resolve my negative experiences with short chainstays. Going from a bike with a slack STA and short RC to the Geometron G1 with 79 ESTA, long wheelbase and long RC was a revelation but it wasn't great in a lot of situation (very tight trails, riding on flat ground). Then I switched to a more moderate big bike (XXL Megatower with slightly slacker ESTA, slightly shorter WB, slightly shorter RC) and it's so much more versatile. It's surprising actually how much better it is.

Posted by: craw

It's surprising actually how much better it is.

When it comes to MTB geo I am genuinely stoked when I hear/see someone finds something that works great for them. I'm glad you got to try enough bikes to find what puts a smile on your face. **two thumbs up**

i prefer the titan mullet with the 452mm cs to the full 29er rise with the 445mm cs on tight alpine tracks

Posted by: craw

Posted by: Vikb

Posted by: craw

Isn't a bike ultimately a big lever pivoting on the rear axle? Weight closer to the rear axle has less leverage on the rear axle effectively weighting the whole lever less. Longer chainstays place the weight further forward effectively increasing leverage on the rear axle (traction) and on the front wheel (steering pressure). 

That's definitely not correct in terms of how to understand weighting the wheels. You can't add weight to both wheels at once that would make no sense. You've only got a finite amount of weight to share between your contact points with the ground. If you move your CG between the wheels you are putting more weight on the wheel you move the CG towards. As I mentioned above that can be achieved a number of ways [CS length, STA, front centre, etc...]. There is no lever effect in play as far as weighting wheels goes. 

All that said I'm not suggesting short/shorter CS are a good solution for everyone. In fact that's exactly opposite of what I am saying. So if short CS and slacker STAs don't work for you I get it and I am glad you found a geo that gives you what you want from your bike. Just keep in mind that because you find it awesome that doesn't mean that somebody else [like me] might find it terrible.

Ya having given it more thought I'm in agreement with this. I think I was trying to work in/resolve my negative experiences with short chainstays. Going from a bike with a slack STA and short RC to the Geometron G1 with 79 ESTA, long wheelbase and long RC was a revelation but it wasn't great in a lot of situation (very tight trails, riding on flat ground). Then I switched to a more moderate big bike (XXL Megatower with slightly slacker ESTA, slightly shorter WB, slightly shorter RC) and it's so much more versatile. It's surprising actually how much better it is.

Vik describes it well, but you aren't totally wrong in terms of talking about a lever effect. Short chain stays in relation to a long front end will create a lever effect. If your centre of mass is closer to the rear wheel, it's going to make it easier to pull up or lift the front end. This effect will be even more pronounced when climbing. And for a taller person, or someone with more mass, this effect will also be more noticeable. 

It's important to consider the rider and the bike as a system, so bike geo, seat position, stem length, bar sweep/rise and your anthropometric measurements will affect how the bike rides. We also have to include our position on the bike as well, so in some instances there will be more rear wheel level effect and in other there will less, or worse more front wheel and you'll be OTB. 

All this is to say there are a large amount of variables to consider, and some of these are in a constant state of change. A bike design/set-up that hits the sweet spot will climb and descend well, but not do either great. A bike that descends great will not climb well, just like a bike that climbs great will not descend very well. It seems we're at the point where a one bike solution works well for most people, but I still prefer having a multiple bike solution, and that doesn't have to cost a ton if you're min-maxing.

Posted by: craw

Then I switched to a more moderate big bike (XXL Megatower with slightly slacker ESTA, slightly shorter WB, slightly shorter RC) and it's so much more versatile. It's surprising actually how much better it is.

i was just generally impressed with the overall balance of the mega geo. they've got things well sorted - with size specific rear centers AND head tubes (stubby ht's on large bikes suck). it's a nice bike.

Chainstay length, tire diameter, bottom bracket drop, total weight, weight bias, and for rear suspension anti-squat, wheel path-nothing to it~ I can say my original Rocky Sherpa with an IRC Racer X-1 tire would not break traction under any circumstance, and it had 18.5" chainstays with a 26" wheel. So maybe people that make bikes know what they're doing?

Another thing he mentions in the video is the idea of getting the grips aligned with the steerer tube. 

I find getting my grips in the right spot (both in terms of height and in terms of stem length) to get the right steering feel to be very elusive. 

By "right steering feel" I mean not nervous or twitchy, or floppy, or like it's going to jackknife when going down steep switchbacks. 

When the bars are in the right spot relative to the steering axis, front axle, bottom bracket, trail/contact patch/my body/???, everything feels locked in and I stop thinking about my bike and just ride. 

I've not found this position to be consistent for me bike to bike, even in cases where two frames have the same head angle and fork offset, the longer bike (significantly longer reach and taller stack) felt better with a longer stem, which doesn't even make sense. 

I'd love to find a formula for what feels good, but I'm not hopeful that I ever will...

^Have you measured bb centre to grip centre or grip edge? It might start to give you a baseline measurement.