Cold Setting rear drop outs
 

How many times can cromoly rear drop outs be cold set from 135 to 130 then back to 135 before it will damage the frame?

You can do 135 to 130 and back to 135 twice, then one more back to 130, maybe.

This question has no specific answer. It's like asking how many times can a paperclip be bent before it breaks. A bunch of times. The same is for a frame. A bunch.


This is not to say that one WANTS to do a bunch, just that many settings can be done with no loss of integrity to the steel.


Now what happens to the joining (brazing, welding) at the bridges is a different question. But if the joinery is well done the answer is much the same, a bunch.


So many people place this frame setting thing on way too high a pedestal. It's time to get off this misconception. When a frame is made it gets set at the "factory". Which actually means that it's rear triangle is bent back and forth a few of times until it's right. then out in the field it gets bent again to reset the width, again actually a few back and forths until things are at the new "right". Then another time later it gets reset to a different width requiring a few more back and forths. so after a few settings one actually has done many little settings.


Lastly I'll add that I have never seen a frame failure that was from said resettings that also wasn't because of poor joinery. The stay failures I've seen are generally because of rust, fatigue cracking, chainring teeth sawing through the stay and such. All are
many cycles types of failure with some wrong aspect at play. Not the work hardening that occurs with resetting the width. And I have done what some would say are horrid things to rear triangles. Like setting from 120 to 145mm. Like collapsing down to, maybe, 80mm then back to 125 that was the goal. Like straightening a seat stay bent in from a car's bumper. Andy.


And just to be nit pickingly clear- I'm talking about steel frames.

Set it to 132.5 and you can go both ways, Trek did this with their early '90s 520 frames, I have one and have used both 130 and 135mm spaced wheels without any problems.

See : Metal fatigue https://en.wikipedia.org/wiki/Fatigue_(material)

This is smart advice if you really need to go back and forth between hub sizes. Today Surly does this with the Cross Check and there are at least one or two other bikes out there that are made like this.

+1 to Andy's comments that there's no hard rule for this. Part of this also depends on how much back and forth is involved in each change.

My rule is to know what you want before doing anything. If you do, there should be no reason to go back. Certainly no reason to go back and then forth again.

I set my old 531 frame to 132.5 so I could run either size hub. Surly does this, I copied them.

I have a 130mm steel frame that I've been running a 135 hub in for much of the past year without resetting (i.e. the frame is still spaced for 130). I imagine the wheel isn't as perfectly centered as it would be in a properly set frame, but I can't detect any difference in road handling. It's a bit harder to get the rear wheel into the dropouts, but not by that much. I suspect the RD hanger alignment changes a bit as well.