Re: Curved seat stays

[Werehatrack]

On Fri, 6 May 2005 02:29:59 -0400, "Nobody" <[email protected]>
wrote:

>My Cannondale aluminum frame has seat stays that curve from the inside out.
>What is the purpose of this?

I have been told that it gives more tire clearance, but that
explanation doesn't wash. I have concluded that the principal
advantage is that it looks neat. And it gives the salesmen something
to point at and act like it's *special*. Claims have been made that
it provides a little flex in the frame and gives a smoother ride, but
I sure as hell can't see any such advantage in mine; I think that
claim is just marketeer hype.

--
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[Sheldon Brown]

I believe the laterally curved seat stays originated with mountain
bikes, where they actually do have functional value:

Being wider at the top gives better tire clearance.

Being narrower where the cantilever brake pivots are is generally
desirable as far as the brake setup is concerned.

Translating this design to a bike with caliper or disc brakes, however
is the triumph of style over substance.

My Hetchins has longitudinally curved seatstays and chainstays, but I
like it despite that fact.

Sheldon "Likes Straight Tubes Except For Fork Blades" Brown
+----------------------------------------------+
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[Werehatrack]

On Sat, 07 May 2005 13:24:17 -0400, Sheldon Brown
<[email protected]> wrote:

>I believe the laterally curved seat stays originated with mountain
>bikes, where they actually do have functional value:
>
>Being wider at the top gives better tire clearance.
>
>Being narrower where the cantilever brake pivots are is generally
>desirable as far as the brake setup is concerned.

Not necessary, however, as it's easy enough to simply offset the
pivots on the tube so that they're closer to the wheel
centerline...as, in fact, was done on several frames I have. The
S-curve does permit them to be mounted more centrally on the stay
tube, but I don't see that this is a terribly compelling reason.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

 

[Sheldon Brown]

I wrote:
>
>>I believe the laterally curved seat stays originated with mountain
>>bikes, where they actually do have functional value:
>>
>>Being wider at the top gives better tire clearance.
>>
>>Being narrower where the cantilever brake pivots are is generally
>>desirable as far as the brake setup is concerned.
>
Werehatrack wrote:
>
> Not necessary, however, as it's easy enough to simply offset the
> pivots on the tube so that they're closer to the wheel
> centerline...as, in fact, was done on several frames I have. The
> S-curve does permit them to be mounted more centrally on the stay
> tube, but I don't see that this is a terribly compelling reason.

I never said that it was a "terribly compelling" reason, but some bikes
use very fat tires on very skinny rims, (not a good idea, but quite
common) and this is a way to make such setups work slightly better.

Rear canti studs do generally mount off center on the stays, but if the
stays are way far apart to clear super-fat tires, a bend like this can
greatly simplify cantlever brake setp.

It is by no means the only solution to this problem, but it's one that
does work.

Shimano's "parallel-push" V-Brakes are another solution.

Wide rims to match the wide tires are yet another.

Sheldon "Not Terribly Compelling" Brown
+------------------------------------------------------+
| It were not best that we should all think alike; |
| it is difference of opinion that makes horse-races. |
| -- Mark Twain |
+------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[[email protected]]

Sheldon Brown wrote:

> >>I believe the laterally curved seat stays originated with mountain
> >>bikes, where they actually do have functional value:
> >>Being wider at the top gives better tire clearance.
> >>Being narrower where the cantilever brake pivots are is generally
> >>desirable as far as the brake setup is concerned.

> I never said that it was a "terribly compelling" reason, but some
bikes
> use very fat tires on very skinny rims, (not a good idea, but quite
> common) and this is a way to make such setups work slightly better.
>
> Rear canti studs do generally mount off center on the stays, but if
the
> stays are way far apart to clear super-fat tires, a bend like this
can
> greatly simplify cantlever brake setp.

Rick Hunter (http://www.huntercycles.com/mainpage.html) builds
cyclocross bikes with curved seat stays for greater tire clearance
for more or less this reason. Of course, cyclocross bikes tend to
run wide (ish) tires on road-width rims. And use cantilever brakes.
The stays on his bikes also look nice, and give a distinctive
appearance, which is not a bad thing for a custom or small-shop
framebuilder.

Ben