loose crank

i bought my son (16) a new unicycle sometime back. he is quite an accomplised rider. he learned how an a cheapy i picked up at a garage sale. the new one was around 400 bucks. he also has a garaffe. never had a problem with the cheapy or the garaffe, but the trail cycle has a problem. one of the cranks keeps coming loose. have tried lock tite, but it doesn’t hold for very long. any ideas out there will be appretiated.

what kind of cranks are they

What uni is it?
Very hard to tell if we don’t know what uni it is :slight_smile:

Re: Loose crank

Philipp E. Imhof wrote:

> Hi!
>
> I am just starting to learn unicycling. My new unicycle (bought it a
> few days ago) has a problem with its left crank: after 20 - 30 mins
> of practicing, it gets loose and I have to tighten it. Even if I
> tighten it with (nearly) all my force, it gets loose after a while.
> The right crank, however, is OK.
>
> What can I do? Would it be a good idea to put some glue on the nut?
>
> Thanks for your help
>
> Philipp

Be careful with loose cranks. Riding on a loose crank can damage the
taper on the hub or the taper on the crank. The damage can be enough
to make it impossible to ever get the crank to stay tight and the crank
or hub is ruined.

Here is a procedure that will make sure your cranks are properly tight.
The big trick is the use of a torque wrench. Doing it without a torque
wrench means that you’re guessing and guessing can lead to a loose
crank. The second trick is to put threadlocker on the nut.

Here’s the procedure as written up by U-Turn:
http://tinyurl.com/blcbl
Or go to http://www.livewireunicycles.com/ and check the Technical
Articles

Loctite Threadlocker will keep the crank nut/bolt from working loose.
It acts kind of like glue. It is specially designed to keep threaded
fasteners (bolts and nuts) tight. Threadlocker goes by different
brands in Europe. If you can’t find the Loctite brand you can find the
same stuff in a different brand. Just ask for threadlocker at an auto
parts store and you’ll get the right stuff.

If you don’t have a torque wrench then have a local bike shop do the
repair. Also have them put Loctite on the nut. They may think it a
little strange but it really does help for unicycle cranks. And have
them get it to 40 foot-pounds of torque.

U-Turn recommends blue Loctite. I have always used red high strength
permanent strength Loctite on the nut. Even though the red stuff is
rated as permanent strength it is still easy enough to break the bond
with a socket wrench and remove the nut later.

If you follow those steps and still have problems with the crank
getting loose then you have either a bad/damaged hub or a bad/damaged
crank.