How did I kill my crank?

quozl

Cycling home today on the single speed bike and noticed that the right cleat was a bit soft feeling. Didn't know if it was the cleat, the shoe or the pedal.

Got home and found that the pedal is loose and I've stripped half the threads on the right hand side crank.

I've been off the bikes for the best part of the last 3 months thanks to chest infections so I don't remember what I was doing to the bike back then. I put the new pedals on but how did I **** up so badly that I've now killed the crankset?

My best guess is that I put the pedal on finger tight and forgot to actually tighten it properly. Any other suggestions? I have grease on the pedal threads and know that I should tighten them properly but guess I didn't.

Reason I really want to know is that I want to make sure I don't do the same thing to the replacement crankset

Also, is there any hope of getting the crank re-threaded? I've actually put the pedal back on and it seems secure enough as I want the single speeder for the ice tyres tomorrow. Good bits of aluminium thread fell out with the pedal so I really wouldn't trust it beyond some gentle pedalling until the ice risk is gone.

Alek

Most likely you haven't tightened it well enough - I put grease on pedal threads too and never had a problem. I honestly doubt you can have it re-threaded, but if it holds "just about" you can degrease it well and epoxy the pedal in.

Darkglasses

A friend of mine bought a second hand bike with this problem, not sure how it happened, but I asked the proprietor of Bee cycles what the story was with repairing the crank, and this is what he said

...it is possible to fit a pedal bush to the crank, it's like a sort of helicoil, I've done it in the past but the results aren't really that great, once a pedal is fitted to it, it can't really be removed again. If the threads aren't completely gone it may be possible to just run a 9/16" tap through it to clean them up and re-cut any damaged threads.
I don't have the pedal bush tool because I don't like the results of using them, if the threads are beyond being repaired with a tap it's just better to replace the whole chainset even though it can be expensive!...

quozl

Thanks guys. The worst part is the feeling of monumental stupidity! Bah!

Lumen

This can happen if your pedal bearings start to seize. The crank rotation then unscrews the pedal.

Can be avoided by keeping the pedal on tighter or keeping the pedals well maintained.

NeedMoreGears

something similar happened to a crank on an old beater I had a few years back. The threads nearest the pedal were stripped but not too badly. I recut them by is crewing in the pedal from the wrong side.

It worked out ok but there's always a risk you could damage the pedal. In my case the bike was already a junker so I was happy to take the chance given the crank was already a write off

CramCycle

Similar to dark glasses, I was working out in Tallaght so I asked CSS could they do anything. They fitted in the coil after drilling the old threads out but warned me it would not be as durable or as safe as a new one.

Went onto cycle it for another 2 years until the frame broke itself, never had an issue

quozl

I have the pedal back on and cycled in this morning on it as I wanted the ice tyres.

Felt secure but I found about half the threads attached to the pedal last night. The pedals are brand new but they're just 20 euro Shimano SPDs. Good strong steel shafts so I'm not too worried about them getting damaged and it'll be a week or two before any new crankset arrives. Time to order one, I'll never trust that crank again after picking all those crank threads out of my pedal threads!

Eamonnator

This happened to what was a good crank of mine, many years ago.
I coldly afford a new one.
I brought it to a place in Drogheda. wav1, who posts regularly on this forum, installed a helicoil thingie. It was a perfect job.

O.P. if yours is a good crank, you might do worse than contacting wav1.

eeeee

Stupid question but I thought pedals were meant to go in finger tight and tighten as you pedal?

I experienced this on one of my bikes. My legs are very different strengths and I changed the bike back to flat pedals there before Christmas. The left pedal ( weak leg) came off in 5 mins me doing it alone. The right pedal ( string leg) took 2 of us 20 min to remove. I thought it was because the strong leg pedalled/screwed it in further?

May need to tighten the pedals on all my bikes now :eek:

quozl

I've seen that mentioned online by a few people Gadetra but every more reputable source I've seem has said it's important to do them up tightly. I'd tighten them if I were you.