Re: [CR]RE: to squeeze or not to squeeze? that is the question...


Example: Racing:Beryl Burton

Date: Tue, 20 Feb 2001 17:23:29 -0500
To: Bicycle Classics inc <bikevint@tiac.net>, <classicrendezvous@bikelist.org>
From: Harvey M Sachs <sachs@erols.com>
Subject: Re: [CR]RE: to squeeze or not to squeeze? that is the question...
In-Reply-To: <3.0.32.20010220121650.00ef0070@pop.tiac.net>


Some thought and real experiments lead me to disagree this one time with Mike Kone on one or two things in his very thougtful post:

<snip>
>MK: 134mm axles will not work for 130mm space unless one believes that 2mm on
>either side of the locknuts is OK - I don't know anybody who is comfortable
>with this risk.

HS: Actually, I'm comfortable with this. I believe that the wheel is _located_ by the axle, but held in place by the QR or nuts. Consider a really lousy experiment: Assume a horizontal dropout. Now, compare the peak force of a rider "stomping" in low gear with the impact of the biggest bump that just doesn't bend the axle. I suspect they are of the same order of magnitude. If the axle doesn't slip, it would suggest that the QR clamping is carrying the load. But, I could be wrong -- the argument surprised me the first time I heard it.


><snip>
>
>MK: Finally, I hope folks will realize that cold setting a frame to
>change the
>spacing rarely causes a failure, but it does kink the seatstay and
>chainstay. To do a re-spacing correctly some builders will actually remove
>the chainstay and seatstay bridges and then install or move them after the
>frame is cold-set. This is a tad nuts, but it can minimuze the stress in
>those areas.

HS: Bike tubing of usual types withstands a few cycles of cold setting quite well. Setting the fork ends by a couple of mm in about 180 mm, or about 1%, seems to be well within tolerances. My procedure is to pull at the drop-out, so the strain can be distributed along the length. If the tube "kinks", which I take to means developing a wrinkle or kink, it would seem to me that the brazing operation had been done at much too high a heat level. But, I could be wrong. I have not had this problem.

Now, don't try this with aluminum or unobtanium...

thanks!
harvey sachs