So i have a set of these pretty things sitting on an idle peugeot frame I have, and ive tried to remove them, only to find the threads are shot. much of this could be due to me trying to pull them off with brute force with the crank pull tool.
so 1) is there any hope left to get them in useable order again?
and 2) how do i get the crank off now anyway. it’s stuck on real tight
cheers
The only way I can think of to get them off now is a hammer.
Did you use the correct crank puller? There are 2 common types, and using the wrong one would cause this problem exactly.
Which one do you have?
There was a thread on this a while ago. Do a search and you should be able to find it.
To summarise, a lot of people said that the best way to remove threaded cranks is to remove the nuts and go for a ride around the block until they fall off. Can damage the bottom bracket though.
So, did you get them off?
Well, id already pulled apart the rest of the bike so i need to put it all back on to give it a ride (lazy). in a fit of frustration i took to it with a mallet :oops:—> baaad move. i ended up bending the very chainring that i wanted to use 
I saw someone on another forum poured boiling water on it in the hopes that the quicker expanding aluminium crank would come off the slower expanding steel bb. it didn’t work for me when I had that problem (too much crap in there I think) but might be worth a shot.
I just gave up and my lbs got it off somehow with their uber park crank puller and maybe cleaning the threads. Then the next time I just used the ride method with success
This is a bit of an urban myth: the aluminium may expand faster, but if so, it also expands in the direction of the axle hole: making the axle hole smaller, and clamping down harder.
Bugger
Not so, if that was true then you would never be able to shrink fit items together.
It expands more not faster, but 25 -> 100ºC isn’t going to cause much expansion, plus you’re not able to heat the crank independently of the axle.
If your puller threads are stuffed:
+1
True… I’m confused now because I remember doing an experiment with a metal ball and ring: the ball would just fit through the ring when the ring was cold, but the ball did not fit when the ring was hot: apparately because the ring expanded in all directions, including making the hole smaller. Have I remembered this incorrectly?
Aha…I have got this the wrong way around: heat the ball and it won’t fit. Heat the ring and it will. Physics was only 9 years ago.
material properties was such a long time ago… i found this http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/thexp2.html for mechanics nerds which might shed some light, but i think we’ve determined that method is shady at best. unless you’re game to try it with a blowtorch heh heh