jharley

Damnit!!!

Almost done with a road frame I've been working on for a little while, back-porch-jigless-after-work project. Its actually come out really well so far. However, I brazed on the chainstay bridge this afternoon and forgot to throw on my dummy axle before getting started. My rear spacing went from 130 to 126. Must have been some shrinkage. Everything is still well aligned.

Do I remove the chainstay bridge and redo it with the dummy axle in place?

Or do I just cold set the thing?

I am guessing cold setting it would be the lesser of two evils in terms of chainstay integrity. Opinions?

Thanks!

MassiveD

There are frames sold with 5 mm of cold set to them, to fit two sizes. I wouldn't worry about it.

unterhausen

I'd try to witch wand it. There was a video of someone aligning a bike using witch wanding posted here not all that long ago

Steel shrinks on the side that was heated. In the future, you should also heat the outside of the chain stays. You don't have to get them red

jharley

I had never heard that term before....here's what I found (for future reference.) Interesting...

https://www.bikeforums.net/showthread...fillet-brazing

https://www.framebuilderscollective.o...-Witch-Wanding

Don't think I am going to mess with that now, but nice to pick up a little bit more knowledge. Will heat both sides of the stays in the future. Thanks!

unterhausen

I don't think you can hurt anything by cranking up the torch and heating the outside of the stays a little. Everyone that has built a steel bike has seen the rear triangle shrink because of the bridges. Nowadays I heat the outside of the stays opposite the bridge as a last step.
thanks for the links, here is the video, witch-wanding starts at 3:18

Henry III

Just run a 6/7 speed wheel and just play it off like you meant to do it.

Andrew R Stewart 

Stays always pull inwards after bridges are installed. Many will over space their axle width by about 5mm in anticipation of this. Using the torch to thermally move the stays will work, as well as simply bending them out. Andy.

jharley

Went out there and hit the outsides of each chainstay with the torch along a 6 inch section adjacent to the chainstay bridge. Heated it to just barely red as in the video. Spacing is now perfect again. Awesome! Thanks!