Re: [CR]Death Blow to a campy crank spider arm?

(Example: Framebuilding:Tubing)

From: <NortonMarg@aol.com>
Date: Sun, 13 Jul 2003 18:54:34 EDT
Subject: Re: [CR]Death Blow to a campy crank spider arm?
To: Bikerdaver@aol.com
cc: classicrendezvous@bikelist.org

In a message dated 7/13/03 2:06:51 PM Pacific Daylight Time, Bikerdaver@aol.com writes:


> I now have what appears to be a bent crank spider arm(s) as
> about 90 degrees of the large chainring rubs the derailluer cage for each
> rotation. Does anyone have a way or repairing this? Should I take a mallet
> to it or
> what?

If you have a lathe available, mount the arm with chainrings on an axle (use a bolt so it stays put), remove the bolt and put the assembly on the lathe centers. Check your runout with a dial indicator on the chainring. There is a tool for straightening the spider of a steel crank that is a heavy bar of steel with a slot near the end that is wide enough to slip over a spider arm so that you can lever it in or out a tad. You can make your own tool, but be sure to radius the edges so you don't leave marks on the spider. I suppose you could do this on the bike if you managed to mount a dial indicator on either the downtube or seat tube.
Stevan Thomas
Alameda, CA