On Monday, Oct 14, 2002, at 12:58PM, <LouDeeter@aol.com> wrote:
>I would really like to understand this as it is something all of use will encounter time and time again. Is there a rule of thumb that
>framebuilders and pro shops use when deciding whether they can spread or not?
Here are a couple of my "rules": 1. 120 to 126 or 126 to 130 no problem. 2. 120 to 130 replace the bridges 3. 531, SL, and Vitus tubing no problem 4. 753, SLX, Prestige, or anything heat-treated replace the bridges. 5. Align with hands only. 6. No 6' long 2"x4"s or other cheater bars. 7. Align as you go.
I've aligned hundreds frames under the best and worst conditions. Having and alignment table with dial-gauges is really nice but most folks don't have access to these tools. The string method works fine even though it's not ideal. Know your own strength and the limits of the tubing. I watched a fellow mechanic fold the right CS and SS on a prestige frame by pulling too hard. If the right CS is dimpled it will move easier than the left side. Different steels have different "memory." The memory of the tubing is where the steel acts like a spring and wants to return to the state it was in before "bending." Cold setting pushes the steel beyond its elastic limit and kind of resets the steel's memory. (Can anyone else explain it better?) If I can I always set the frame aside overnight after alignment and recheck it in the morning just to make sure the frame didn't creep back. Alignment of bike frames isn't rocket science, except maybe the part about metal's memory, and can be done by with as little as a frame and two hands. If you have the help of a pro and a ground plate and dial-gauges great, but if you don't it's still a job that can be done at home. Hope this helps folks. enjoy, Brandon"monkeyman"Ives SB, CA