Suddenly left crank wont stay tight

On the second day of our Huntsville AL MUni campout, deep into the MUni ride, far from camp, all of the sudden my left crank was loose.

I carry that tool so I tightened the nut. 100 yards later…loose. I did this every 100 yards or so for a while. I bashed it against a tree, which seated the crank better and wedged some bark in there acting like loc-tite.

But, alas, its loose again.

Could I have merely stripped the nut? My first step was going to be replacing it. I assume the nut is softer metal than the screw coming out of the hub, because it would be horrible to have to replace a hub, but simple to replace a nut.

Prior to its being loose, I hadn’t touched it in over a year.

the square hole of your crank is now ruined, and so is the crank.

it will never stay tight again

this happened because you didn’t maintain the nut tightness, and as soon as it works itself loose (always seems to be the left one) it will ruin the crank if you ride it

if you mark them like here : http://www.unicyclist.com/forums/showthread.php?s=&threadid=25283&highlight=your+nuts

you can see right away if they are still as tight as you left them

Thanks for the advice and link

Set of Cranks still trumps new hub (considering lacing labor adn lack of expertise)

Re: Suddenly left crank wont stay tight

yep, no more thought needed.

Was it a cotterless crank or other?

Sounds like it is indeed the old problem of riding on a crank when it is a little loose and rounding out the square hole. It is very hard to tell if a crank arm is “a little loose” when riding. Generally you only notice a loose crank when it is a lot loose.

The best solution is to periodicly check your cranks for tightness, especially after heavy riding (big drops etc). Also note that aluminium cranks need to be tightened far more often than steel.

If you do round out a crank you can sometimes get a little more life out of it by taking the crank off and mounting it at 90 or 180 degrees from where it was (you’ll need to move the other crank as well).

If you are very unfortunate and have been riding on a loose crank you may have also damaged your axle as well. I have done this a few times and it requires a complete wheel rebuild :frowning:

Hopefully buying new cranks will fix your problem.

I don’t know if this is a good idea or not, but it worked for me…

On my first unicycle one of the cranks came loose (and I didn’t notice until it actually fell off, so I had to walk a long ways) I ended up having to replace the bolt, but nothing else (it was lost). What ended up working was putting a couple of thin layers of aluminium foil around the hub before putting the crank on, and then tightening it down really well, and with plenty of thread lock. It has held up for at least a couple years now without a problem, under all sorts of riding conditions. Hopefully you won’t have to replace any expensive parts.

Here is a post about puttin them in the oven to mold them to your axle. Its in the post from Al Lieffring.

http://www.unicyclist.com/forums/showthread.php?s=&threadid=40478&highlight=crank

You folks are great. Thanks:D

I really think you just need to find a tree with more sap. That ought to do it.:smiley: Oh and where is that video? That would be appropriate to post in this thread.:smiley:

I am glad this came up, cause i am having about the same exact problem. i am probably going to try that alluminum foil method. That sounds like it might actually work pretty good. I was going to put it in the oven this morning, but when i want to get the crank off it won’t.lol.
Thx