Damaged crank threads - any solution?

D!armu!d

I was changing the pedals from my old bike to new recently - first pedal went on fine, but there was no shifting the second one. I put the original pedal back on my new bike until I could get a better spanner to fix the problem. I didn't tighten the original pedal too tight as I didn't want the same thing to happen, but after a a few days cycling the pedal came loose and damaged the threads in the crank.

A pedal will not fit back on now so have I fecked up the whole chainset? Its on the right hand side. It was a sugino 175mm crank and I was looking to get an exact replacement. I phoned a few bike shops and none seem to have them. Any solutions?

Thanks

Raam

You know that one of the cranks is reverse threaded?

penexpers

should be able to pick up the same crankset on eBay. If you have wrecked the threads then the only option is to get a new crankset. You should use grease when installing pedals and they should come off easily enough.

72hundred

Re-apply WD40 to it every hour for a few hours and then try the next day / 48 hr's later. -That worked for me for a stuck pedal.

psycholist

a decent bike shop should have a tap to re do the threads on the crank
cycleways/cyclesuperstore andshould be a whole lot cheaper than buying a new one... i wouldnt recommend you trying to bate the pedal in a bit then tightening it and re threading it that way but you could do it that way aswell

D!armu!d

Thanks psycholist,

I was hoping there'd be something like that to solve it. but I just phoned cyclesuperstore and they said that if you redid the thread they would be too wide to fit any pedal.

Is there anything else worth trying before I 'bate' it in? The crank will have to be replaced otherwise so no harm in trying..

RobFowl

diroche wrote: »

. Any solutions?

Thanks

New chainset I'm afraid

RobFowl

diroche wrote: »

I It was a sugino 175mm crank and I was looking to get an exact replacement.
Thanks

I have a worn 2005 Dura ace 170 ml one spare if its any use

kenmc

you could try to reset the threads slightly by screwing the pedal in from the OTHER side of the crank. You MIGHT just get enough purchase on the 'inside' threads to allow you to reform the 'outer', damaged threads. Then you MAY be able to put the pedal on properly once again. Certainly worth a shot

rob1891

diroche wrote: »

Thanks psycholist,

I was hoping there'd be something like that to solve it. but I just phoned cyclesuperstore and they said that if you redid the thread they would be too wide to fit any pedal.

Is there anything else worth trying before I 'bate' it in? The crank will have to be replaced otherwise so no harm in trying..

What they are trying to say is that they don't want to fix it for you, it's not cost effective, they don't have the time, expertise, inclination, tools, whatever. Which is fair enough as for a cheap crank, it might not be cost effective. However, it is most definitely possible!

You'd be better off taking the bike over to a shop and let them have a look at it before they decide that it is a write off. Obviously don't bother with CSC given their attitude with you over the phone. (Bike Rack Cabinteely maybe?)

Firstly, your thread probably isn't totally destroyed. Without looking at it no one can tell if it can be retapped successfully. You could try threading a pedal through from the inside of the crank arm. The threads on the inside are might not be damaged, and if you can get a pedal to mate with them you could then drive it through the damaged threads on outside of the crank. After doing this the outside threads probably won't be perfect, and you'll have to be super careful installing the pedal in future, but it would get you going again. (Obviously the thread tapping tool of a bikeshop would do the job better.)

If the thread really is totally destroyed you need to install a "Helicoil". This involves drilling out the old thread, re-threading the larger hole with a larger thread and then installing the "coil" which fits into the larger thread and reduces it to re-create your old pedal sized thread.

Simple really, but with the disposable attitude to most things these days, I don't know if a bike shop would be bothered to do this. The coils are cheap but the kit (different for every size thread) isn't, 40 euros ish, nothing to a bloody shop but for a once off DIY its a bit much.

Chips Lovell

Been there done that in my younger and dumber days. Took it around to a few bike shops looking for it to be tapped, chased and get a helicoil in. No one would do it. Investigated doing the job myself, but the tools were too expensive to make a one time job worthwhile. Tried to buy just a replacement left hand crank arm. No joy. Ended up buying a complete replacement crankset.

Thomas_S_Hunterson

Try Square-Wheel on Temple-Lane.

They aint box-shifters and the main part of their business is repairs. (wont do repairs on cheap supremarket bikes though)

jefferson73

Been there, ruined a Gipiemme Crono crank set, it sucks

http://www.hubjub.co.uk/sugino/sugino.htm

D!armu!d

For any other fools out there...

After trying a few different bikeshops I got the crank fixed by The Bike Rack in Cabinteely. Turns out they were able to fix up the threads enough to fit a pedal on, but could have fitted a helicoil if needed.