[CR]The "flexing" of frames


Date: Wed, 05 Mar 2003 11:21:55 -0800
From: Brandon Ives <monkeylad@mac.com>
To: ADP <aphillips9@mindspring.com>
cc: classicrendezvous@bikelist.org
Subject: [CR]The "flexing" of frames

On Wednesday, March 05, 2003, at 10:33AM, ADP <aphillips9@mindspring.com> wrote:
>Racers are tough. Anything not steel, that has been raced hard on (by a
>big guy!) can be bent after just a season.

Actually, no they can't unless they're crashing them and this does go for steel too.
>Had a customer come in with a carbon fiber bike that the rear wheel wouldn't even line up properly
>anymore.

If it doesn't line up now it's either broken somewhere, or was never actually lined up. Of course this also assumes that the wheel is the same.
>She got it from a racer. My upstairs neighbor has got serious bottom bracket sway in his scandium Quattro. Scott is a stocky, powerful,
>400+ mile a week guy.

He's gotten stronger and the frame hasn't gotten weaker.
>Steel is more resilient, but my SO - big ring grinder that he is (man with
>knees of steel!) has broken a few frames - broke (era content here) an
>early 80s Merckx seat tube near the bottom bracket, and did a job on a
>Paramount.

Odds are this is from overheating the stay during the building.
>When do steel frames fatigue? Or do they?

Like anything else you buy used you gamble on how it was used before you got it. The three main breakages you get in steel frames are drive-side rear dropouts, chainstay breaks like your SOs from overheating, and the can-opener on the DT from not rounding the bottom headlug point under the DT. The first problem is to inspect the DO and see if you can find cracks. The chainstay problem from overheating is something you can't really tell until it cracks. On the third problem spot I just don't buy frames where the bottom point of that lug hasn't been rounded.
>I know I'm at less of a risk with my interest in smaller frames that fit,
>but something like a 56cm could be really beat! How do you tell?

I'm actually more wary about smaller frames because many of the builders have the same idea as you, that they won't be used as much. I remember a woman I worked with in '90 ordered a custom Eddy Merckx in a 46 or 48cm. It took 6 months and was one of the sloppiest built "custom" bikes I've ever seen. It had file marks everywhere that showed through the chrome and really sloppy brazing with uncleaned splatters. I've seen quite a few others like this while looking for frames for Mitzi. The best advice I can give you is to look for little used frames instead of "deals." As Chuck has said many times virtually unridden bikes can be found pretty easily.

If you want more information on this check the list archives for this list and the Framebuilders list since it's been discussed ad nauseam in the past. good hunting, Brandon"monkeyman"Ives SB, CA