Buckled downtube, safe to cold stretch?

[daccordimark]

Re:

Just to add a different experience, I had a frame damaged in the same way but even my forks were bent too. I replaced the forks and carried on riding the bike. I think it lasted about a year before the frame snapped where the tube was wrinkled. I heard a creaking noise as I rode up a hill and when I stopped to look the down tube was split underneath almost half way round the tube. No great drama or injury just a slow ride to work.
Mark.

 

[keithglos]

There is really only one place in a bike frame where a breakage will stick your face straight into the road, if the fork column (steerer) breaks at the bottom crown race.

I have never seen a 531 one break, but when racing in France in the 60s they could not believe we did not have a bit of wooden broom handle up the inside of the fork crown, and were reluctant to let us start. Explaining that our tubing was better would not have helped.

Keith

 

[Pionir]

I wouldn't

It's likely the steel exceeded the elastic limit and went through plastic deformation, which means Hookes Law no longer applies and the properties are permanantly changed.

It may still be strong enough, but as said by Nob, is it worth the risk? What if it fails going down a hill at 30mph and you go face first into a tree?

 

[Jonny69]

Metallurgist hat on. Non heat treated steels are quite happy being a bit bent and then bent back again. Anything gas pipe, just stick a jack on it and bend it back and forget about it. Reynolds 531 isn't heat treated. Heat treated steels are different, the higher strength comes at the cost of a bit of ductility ie you can't stretch it as far. Pretty sure SLX is heat treated. You can try pulling it back, but it might tear the tube. What you could do is strip the paint off and lightly polish the surface. When you stretch it back, if the polished finish goes grainy you know you've pulled it too far and it'll probably not last long. I'm also surprised the fork didn't get bent.