How do I stop stripping cranks?

I’ve been riding for a couple years (on a torker cx) but only got serious a few months ago when I started doing some low-key trials riding. After a couple weeks of hopping I noticed my left pedal was a little loose, and a few days later it fell off. The crank was completely stripped so I ordered new cranks (I believe they were the torker LX cranks from amazon) and had them installed at a local bike shop. Today (about a month and a half later) I noticed that the left pedal was again coming lose. I stopped riding immediately and brought it to a bike shop to prevent further damage but they told me it was too late and I had already stripped the crank again.

I’m going to keep riding until it actually falls off but how can I keep the cranks from stripping so fast (or at all) in the future? The people at the bike shop seemed to think there was nothing I could do about it but keep buying new cranks every few months. Reading through some other threads suggested that the cranks were on backwards (which sounds like a mistake I could have easily made myself) but I doubt the bike shop would have done so. Also the bikeshop I took it to today is different from the first one and they didn’t notice anything out of place.

Should I buy higher quality cranks? Tighten the pedals after each session before they get loose enough to strip the threads? Any input would be appreciated.

P.S. As you can probably tell I’m not very mechanical, but I’m working on it.

i would keep everything nice and tight…you got a spanner??

heeey nice post #1 and you don’t have the standard"confused newbie" thing under your name!!!


you could get a better unicycle :slight_smile: , your pedals may be bad. I’m not sure on the strenth of those cranks.

he probably meansWITHOUT getting a different uni…

you should probably get an allan key set and a spanner…

getting a new uni solves all hahaha:D :roll_eyes: , but costs alot.

Do a better job yourself

By going to the auto parts place and buy blue loctite. Install your new cranks yourself, noting the one marked L goes on the left.
Install your pedals with blue loctite on the threads and screw them into the cranks. Note that the left pedal screws in counter clockwise and the right clockwise.
You started pedaling backwards and it’s the left crank that stripped right? :roll_eyes: If your LBS had put loctite on this wouldn’t have happened. But people rarely pedal their bikes backwards !

A new unicycle is a possibility, I’ve been considering getting one more suited to trials riding, but I don’t want to invest in one unless I’m sure it will solve the problem.

Yes I have a spanner, I’ll be sure to keep the pedals tight in the future.

If the strength of the pedals is in question, why don’t I get new pedals instead of a whole uni?

Yes the problem did start when I started riding backwards, I just assumed it was the hopping that did it since it’s such a higher stress situation, that the pedal would start to loosen and then strip the crank. What goes wrong when you pedal backwards without loctite? Why does only the left crank strip?

I also assumed that the left was stripping because that’s the foot I idle with and do the most controlling with in general. Hence my current idea of spinning the seat around and riding with the uni backwards to even out the wear on both pedals.

It is possible that it’s a low quality pedal and not the quality of the crank that is causing the problem. I’ve had a cheap pedal where the pedal threads were undersized. No matter what you did that pedal would come loose.

The only way to fix that is to get new pedals. Preferably pedals that have higher standard of quality.

If a pedal threads in too easily then the threads may be undersized.

If you get a bike shop to put on the new crank, tell them your concern that the pedal thread may be undersized. They should be able to tell if the pedal is threading in too easily. If that’s the case then get new pedals.

Don’t ride the unicycle backwards (in reverse) like that. Pedals are threaded the way they are for a reason so that they tend to tighten as you ride. Riding it backwards like that will make it very likely that the pedals will loosen. Sheldon Brown explains here (scroll down to “Pedal Threading” and look for the word “precession”).

Good pedals with good threads in a good crank should not spontaneously loosen, even if you ride backwards. If you do an extreme amount of backwards riding you might want to Loctite the pedal threads. But there should be no other need to Loctite the pedal threads to keep them tight. If you have to Loctite the pedal to keep in tight in normal use then something is defective and out of spec.

riding backwards would cause a problem, tambourineman, because the pedals are threaded such that they tighten when riding forwards. when you ride backwards, they loosen, and riding around with them loose makes them prone to stripping.

It’s not the unicycle. Under normal use it should hold up just fine if put together properly.

Blue loctite

Is a cheap liquid plastic that hardens overnight into a gummy thread glue. A couple drops will fix you up for 10 cents. It will not lock the pedal tight. That is what red loctite is for (permanent assembly). The pedal will be easy enough to remove later as long as you get the blue stuff.:slight_smile:

I’m going off topic here, but if I ride backwards 50% of the time (practicing my backwards riding, not just randomly riding around), should I loctite my pedal threads? I rode 50% backwards for a few consecutive days and just haven’t been able to ride since (due to injury).

Probably not necessary. Would depend on the quality of the fit of your pedal threads in the crank.

I have never Loctited my pedals and I Loctite everything. It just has not been necessary on any of my unicycles.

Check the pedals and if you ever notice them loose after backwards riding then Loctite them.

If you do Loctite them you’ll need to clean out the threads to get rid of the grease. Use some degreaser and make sure all the grease and dirt are gone. The grease and dirt will prevent the Loctite from getting a proper bond. Then use enough Loctite that it can act as a lubricant in lieu of the grease.

For a thread diameter as large as a pedal thread the red “permanent” Loctite is not going to be permanent. You’ll still be able to remove it with hand tools without undo effort. The larger diameter the threads the more leverage you’ll have on it and the easier it will be to break the bond. Use the red Loctite on a small diameter thread and it can be effectively permanent.

But red is overkill for this purpose. So use the blue medium strength.

I’ve heard that people doing backwards world record distance rides will swap things around so that the right crank is under the left foot. That way the pedals don’t come undone during the ride.

I think it’s strange that you’re stripping pedals.

A few things come to mind. It’s easy to strip pedals if they’re cross-threaded, which usually happens when you mix up left and right. To prevent this, trying getting the first couple theads on the pedal by hand. If you’re using a wrench, and getting a lot of resistance, something may be wrong.

Its possible to weaken the threads by overtightening. You shouldn’t have to muscle the wrench. It should be just a “little” tight.

Lots of people go huge on their unicycles, and usually many other things break before their cranks get stripped.

Loctite won’t hurt, but it shouldn’t be necessary.

I didn’t see it mentioned elsewhere in this thead, the right pedal theads on normally (righty-tighty), but the left pedal theads on the opposite direction. (your bike shop should definitely know this)

Thanks for all the advice. Last question, should I try to get stronger, pricier crank arms or the same aluminum torker ones (and use loctite).

I don’t think it’s matter of stronger cranks.

What I do is, torque the crank bolts, ride few minutes, then torque, ride again, then torque, then after a longer ride torque again. That will get the cranks seated and tight. Still, it’s important check once in while.

Me, I torque to 50 foot pounds, this is higher than most people admit to, but I’ve changed many cranks and never had a problem with this damaging the hub.


I have a KH24" 2007 and I put Bontrager “Big Earl” pedals on it. I do a lot of MUni with it and a fair amount of trials. The right pedal only, started loosening every couple of days. Especially when I was doing practice sets of stairs or rock climbing or just riding backwards for a kilometer or two on dirt roads after a MUni ride. I would feel the loseness and immediately tighten it back up. I got sick of it and cleaned the threads, both inside the crank and around the pedal, real good with dish detergent a a tothbrush. I then put the blue locktite in and never had another problem with the pedal unscrewing. I have not checked this out with material engineers but common sense would tell me that with the loctite there would be no need for grease because the loctite is going to give a thin seperation between the two metal parts. Please correct me if I am wrong. I have not put loctite on the left pedal because I never had a problem there. I still do a lot of hoping on stairs and rocks and backward riding. I also do a lot of direction changes durring skill building sessions and don’t have a problem with either of the pedals. ( the right with the Loctite and the left with grease. My advice is that Grease is the best but backward riding and jumps create additional problems that bicycalist don’t experience. Therefore only if you have a problem use Loctite.


why always the left pedal?

I knew it;)
I am tempted to take a pole ! :sunglasses:
I think maybe we tighten left threaded pedals less torque. Or we are pedal handed, like right or left handed.
It has always been the left pedal that strips this way, that I have seen.
It is not always worn or poorly fitted uni’s that have this trouble. Both my new KH’s have had this trouble.
Most likely because I, rather than Kriss, installed the pedals.
Anyway, a tube of loctite is a must for any hack mechanic, at 3 dollars USA.:slight_smile: