Possible to fix a bent crank?

I have a set of Qu-ax 125mm aluminum cranks, and I just bent one (right), going down a steep hill.

I knew these cranks were not beefy, and have therefore carefully avoided any big drops on them, but I guess I didn’t realize how much pressure you can exert while slowing down on a descent!

My question is: is it possible to straighten the crank again? and if so, how? Should I take it to a lbs, or jam a crowbar through the pedal to try and force it back? (The bend is slight - ie. it is not bent to look at it, but you can definitely feel it when you pedal)

If it is not possible to straighten the crank, I wonder whether it would be possible to re-drill and tap it at the 100mm position - and re-use it that way? And again, would my lbs be equipped to perform such a mod, or do I need to do it myself?

That’s pretty unusual bending a crank with leg force alone, even with relatively weak cranks.

Anyway, are you sure it’s not the pedal axle that’s bent?

Assuming it is the crank that’s bent, I don’t know if I’d be happy bending it back, even if you could do it without damaging anything else. Aluminium doesn’t really bend well - I reckon it would be significantly weakened if it’s been bent and then bent back.

I’d say the best bet would be to get some new cranks (those QuAx ones are pretty inexpensive) - or possibly go for some stronger ones.

Regarding drilling and retapping, it’s possible but would probably cost more than new cranks if you pay somebody else to do it (and that’s assuming that the first 100mm are not twisted).


Says the man who sheared both flanges off of his hub using leg force alone…:stuck_out_tongue:

The Qu-Ax cranks are very weak, they will not stand up to being bent and re-bent. Either adjust to the way the bent crank feels (which isn’t hard), or get a new set of cranks. Qu-Ax cranks are $10 at unicycle.com right now.

Yeah, get some new ones, they’re cheap, I bought three pairs of the 170’s :slight_smile:

Thanks - didn’t know about the sale at unicycle.com.
Unfortunately they’re not at such a good price in the Canadian store - but even shipping from the US they are a great deal!

As for “adjusting to the way the bent crank feels” - I had heard it was bad for your knees to ride with a bent crank - any comments? Also, after getting used to riding on a bent crank (tholub, it sounds like you have experience), does a straight crank feel odd?

I can definitely say it’s odd to ride on a bent crank after riding on a straight pair : P had this experience with my first muni ride. Borrowed a torker, and felt something was “off” but didn’t realize what until we took a closer look at it. Definitely wasn’t bent much, but it was enough to throw the pedal off being flat.

If the crank is bent to the point where you’d be risking knee injury, the crank will be immediately uncomfortable, if not unusable.

Not at all. I’ve been riding for a couple years on a slightly bent crank (thanks for the free cranks, Corbin!) and I don’t notice it anymore than I notice the fact that a straight crank feels straight.

It definitely feels odd to ride on a straight crank after riding on a bent crank, but it only takes a couple minutes to get used to it (in either direction) if the bend is minor. If you want a real experience, try riding on a bent crank and then turning the unicycle around and riding it with the bent crank on the other side–that feels really weird.