# Effects of chainstay length on bicycle performance?



## mozami (Nov 14, 2010)

Do shorter stays really provide snappier acceleration? Suppose everything is the same (wheels, tyres, BB drop, gearing etc). I've been doing some empirical testing with my langster and singlecross and the said hypothesis is 'just' noticeable... however Im not sure whats the major contributor; the extra 35mm difference in chainstays or the extra mass in the drivetrain from the longer chain...
Anyone have any views?
Is it why track bikes have very short stays? and the major trend in newer 29er bikes is minimising chain stay length to overcome sluggish starts (on the track the gearing is pretty high after all)? I suppose the penny farthing would accelerate like crazy!


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## Dave Hickey (Jan 27, 2002)

I based my feelings on ride quality and not science. 

I prefer shorter stays on all my bikes. It provided quicker handling and I feel climbing is easier with the rear wheel tucked up underneath you....


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## UrbanPrimitive (Jun 14, 2009)

I've not come across the claim that short chainstays provide better acceleration. I have, however, come across claims that shorter stays result in snappier _handling_. That is, in part, due to shortening the wheel base. Longer stays are generally considered to provide more stability and keep a better line when under a heavy load. That can be translated to mean it takes more steering to change your path. Riding on a track in a mass start event quick handling is more important as you probably aren't hauling three days worth of food and clothes in your skinsuit. Shorter stays will also result in a slightly lighter frame, but not by much. Shaving off 8mm of tubing that's less than .9mm thick isn't going to make much difference. Decreasing the wheel base, however, will result in much quick handling. Think of the difference between a Porsche and a Ford F150. If you really want to dig into check out thePaterek Manual.


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## mozami (Nov 14, 2010)

UrbanPrimitive said:


> ..Shorter stays will also result in a slightly lighter frame, but not by much. Shaving off 8mm of tubing that's less than .9mm thick isn't going to make much difference. Decreasing the wheel base, however, will result in much quick handling. Think of the difference between a Porsche and a Ford F150. If you really want to dig into check out thePaterek Manual.


I would think the weight saving in the frame is pretty negligible however the longer chain might add a few tens of grams. Other positive aspect of long stays is better ride quality, as you sit less directly over the rear wheel and a better chainline, good for triples. 

Has anyone ever ridden a recumbent, and tried going uphill (same as accelerating)...its really difficult and the long effective chainstays may be one of the reasons...


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## m_s (Nov 20, 2007)

On a road or road-biased bike I prefer a balance. A longer wheelbase can track better over rough surfaces. If I raced on the road I would want different things than for my general riding and training on road and dirt roads. I don't corner particularly hard on my fixed gear, so snappier handling isn't a big deal, and I'll take some extra comfort of a longer frame since I'm seated a lot even over rough ground.

29ers are a different beast. The obsession with short chainstays is because most designs simply lengthen the stays as much as needed to accommodate the large wheel without regard to handling, though this is changing. There is a limit. With 26ers, for example, short isn't always better because going as short as possible means you might end up with a bike that's too rear-biased in its weight and doesn't track well at all as well as getting a front end that wanders on climbs.


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## m_s (Nov 20, 2007)

mozami said:


> Has anyone ever ridden a recumbent, and tried going uphill (same as accelerating)...its really difficult and the long effective chainstays may be one of the reasons...


I think extreme rear weight bias and inability to stand are the reasons recumbents don't climb well. Wheelbase might be a factor, but it would seem down the list IMO.


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## UrbanPrimitive (Jun 14, 2009)

mozami said:


> I would think the weight saving in the frame is pretty negligible however the longer chain might add a few tens of grams. Other positive aspect of long stays is better ride quality, as you sit less directly over the rear wheel and a better chainline, good for triples.
> 
> Has anyone ever ridden a recumbent, and tried going uphill (same as accelerating)...its really difficult and the long effective chainstays may be one of the reasons...


Let's be honest: 20 grams of chain weight isn't going to make a noticeable difference acceleration or climbing. 20 grams of weight added to the chain, then the frame, then the wheels, the tires, the stem, the saddle, et cetera will eventually add up to a significant amount of weight that will effect performance. As for chainline, if we're talking about riding fixed or single, good chainline for triples doesn't matter. You need to line up your cranks with your cog and you're done. No shifting clearance needed. As for the more compliant ride, you're right but maybe not quite dead on the mark. The primary reason for a squishier ride with longer chainstays is they, almost universally, result in a lower angle _seat_stay. The lower angle of the seatstay results in more vertical compliance and thus vibration dampening.

I must apologize if I'm coming off as a know-it all or a [email protected]$$. Just trying to share the stuff I've learned after a _lot_ of digging, but I am well aware that I can come off as a jerk. No offense is intended. I'm just a bit tired and unaware.


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## mozami (Nov 14, 2010)

Good stuff coming through thanks...

Primitive, I've never heard of seatstay angles before but hey you learn everything new everyday...seat stay compliance is a strange fish, I generally go with the thinner the better philosophy

m_s: I have a vassago 29er, the geometry of which can be said to be anti-status quo... Long stays and slack angles and I do really notice the smoothing out of bumps under the rear wheel.


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## apoint (Nov 22, 2010)

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## apoint (Nov 22, 2010)

Shorter chain stays will give you shorter seat stays and a shorter Chain. Add it all up to a good bit of weight. Less energy to turn a shorter chain over 50 mile trip.


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