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Frame Bending(4 posts)

Frame Bendingvobbel
Aug 27, 2003 11:05 AM
I am building a fixed gear commuter, and will be running a surly 135mm hub in an old steel road frame with 120mm spacing. Im wondering how much bending is too much. Thanks.
Home Solutionbigrider
Aug 27, 2003 11:23 AM
I bought a steel frame and stretched it for a 135mm spacing from a 120 mm spacing with no problems.

Here is how.

Get a cable tensioner, the kind you would use to tighten a clothesline, a threaded eyebolt on each end with the barrel in the middle. When you turn the barrel it either shorten or lengthens the distance from the outer edges of the eyebolt.

Place the tensioner in between the stays where the hub would go but put the ends of the eyebolts in that triangular shaped space right above the dropouts. Expand the tensioner a little past 135mm and then reduce it and measure. Repeat and go a little further each time until the space measures 135mm when relaxed. Since you push with even pressure on the stays the frame stays straight.
15 mm is too muchLC
Aug 28, 2003 2:41 PM
You can break the weld at cross piece near the BB, or weaken the chainstays going too far. Normally when your talking about spreading it is no more than 5 mm. i would not trust the frame after bending it that much.
re: Frame Bendingukiahb
Aug 28, 2003 4:57 PM
another consideration is that the dropouts will no longer be parallel after bending , and this could be an issue on a fixed gear as fixie wheels are prone to slippage anyway. FWIW Sheldon Brown does have an article on frame "cold setting"/bending at his site....