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Help! Rounded off bolt on Hollowtech 2 cranks.

neil_sheehan2000neil_sheehan2000 Posts: 529
edited September 2007 in MTB workshop & tech
I'm fairly sure this has been asked before but I couldn't find it with the Search function- sorry.

Anyway, I've managed to round off one of the bolts that holds the crank arm on on my Hollowtech 2 cranks (the non-drive side arm that clamps on to the bottom bracket). Took it to the LBS who told me to take it to an engineer. I live with an engineer, and he seems to be of the opinion that the bolt is too small to guarentee that it can be drilled out with those reverse-thread things without damaging the crank arm. Tried to stick an allen key in there with Araldyte (sp?) so I could just unscrew it and that didn't work.

Basically, I need to ride my bike for Pedal For Scotland this Sunday. I was thinking maybe if I cut the bolt in half (there's a slot down the middle of the crank arm that a hacksaw blade could fit down) I would at least be able to get the cranks off and fit my spare set, leaving me time to worry about the rounded off bolt at my leisure. I'm thinking that with no strain left on the bolt I could at least get the top half of it out using just an allen key. Is this a bad idea? Would it make it even less likely that I would be able to get the bottom half of the bolt out? If this is a bad idea, what should I do instead?

Any help gladly appreciated as I'm running out of time and ideas.


I am... 0 votes

0% 0 votes
Completely screwed.
0% 0 votes
Fine to leave the bolt be for the time being on the assumption that it's probably tight enough.
0% 0 votes
In need of a wizard.
0% 0 votes


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