Chainstay bridge
Jobst Brandt
> Regarding chainstay bridges- they probably won't hurt anything but
> many years ago we did a series of sideways deflection test on frames
> in progress before and after chainstay bridges but with a hub locked
> in the frame and couldn't find any difference with 100lb hanging off
> the axle, frame supported at seat and head tubes.
I wrote about this in this forum years ago and should have offered it
to the FAQ to save us the problem of rehashing it yearly. The purpose
of the little tube was to help people make tire changes. Those who
believed otherwise built frames wihtout them in the days of horizontal
dropouts and discovered that popping a wheel out, jammed the tire
between the chainstays and when they pulled it out of there it was
back in the dropouts and back and forth a couple of times when you are
flustered. That was its only purpose on a racing bicycle. Besides,
the "rear triangle" is a tetrahedron, the most rigid solid figure you
can construct, the rear axle being a short element of the six element
figure.
> Jim Adney started this, I think. Anyway, anyone (D Rinard?) done
> any more-rigorous test here? I'm pretty sure they don't do anything
> unless you need fenders.
Since the advent of vertical dropouts they have no function,
especially with tires barely clearing the seat tube today. The old
saw of wiping tires is also kaput, because one can break a finger
getting it jammed between tire and seat tube. Thanks alot. On the
other hand, I have my Silca Impero pump held by a braze-on behind the
seat tube with plenty of tire clearance.
Jobst Brandt <jbr...@hpl.hp.com>