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-   -   Cold-setting with modern TrueTemper OXPLAT? (http://www.bikeforums.net/framebuilders/801785-cold-setting-modern-truetemper-oxplat.html)

Road Fan 02-29-12 03:19 PM

Cold-setting with modern TrueTemper OXPLAT?
 
I recently bought a custom verylight frame from a private party, built by a well-known builder. When unboxed and test-fiting things, measuring clearances et cetera, I found the rear OLD is 127 mm. The builder (I spoke to him) says he builds for 130 mm, and targets 131 as a final setting so that rear wheels just slip in and out. He says the OX Plat makes a very rigid rear end and will take a lot of force to cold-set back out to 131.

I did a string test and the offset relative to the frame plane seems nearly even. The difference in string-to-seat-tube distances is between 1/2 and 1 mm, so it might be too small to measure reliably with a ruler or a caliper, since I'm eyeballing a string with a ruler. I checked to see if the seat tube is bent using a straightedge and there's no perceivable bowing.

I may choose to "withstand" the inconvenience of muscling my wheel in and out every time, or to cold set it. With this kind of frame tube, are there risks in cold-setting that might not be worth considering say for 531 or lesser alloys? The chainstays are flexed considerably to achieve a wide clearance for 42 mm 650b tires, already.

unterhausen 02-29-12 04:13 PM

It's not as easy to bend as 531, and it will not go lightly. I didn't really understand part of your post, are the chainstays dimpled?
3mm doesn't sound like it should take all that much muscling.

Road Fan 02-29-12 05:07 PM

The original shaping used a minimum of dimpling. At the tightest radius point it's ovalled a little, but none of the pronounced dimpling or flattening that is often done. Builder tried and succeeded at keeping the CS tube as round as possible. It's fully round at the BB shell, where the tubes exit at an angle of perhaps 20 to 30 degrees from center plane.

I suppose what I'm worried about is accumulated work-hardening due to repeated bending.

unterhausen 02-29-12 06:14 PM

Quote:

Originally Posted by Road Fan (Post 13915303)
I suppose what I'm worried about is accumulated work-hardening due to repeated bending.

you aren't going to be bending it to yielding by riding it without cold setting. If you cold set, you will be exceeding the yield stress somewhere, uncontrolled by you. You have to move it far more than 3mm to cold set

Road Fan 03-01-12 05:22 AM

Yes, I AM referring to bending to achieve yield rather than the normal flexing of riding. That frame motion should be completely elastic. And if the CS doesn't exceed the yield stress somewhere, no shape change will be achieved.


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