just recently, myNimbus X Alloy Crank arms broke. i was wondering if anyone new of some strong, yet somewhat affordable, new crank arms. I am looking for ones that can withstand jumping and doing drops.
I am interested to know what you were doing when they broke, in what way they broke, and how they were installed on the uni. Also what length cranks are they?
Do you have any pictures that you could post?
The way that they broke is they got stripped. I was just riding when I noticed they were stripped, but I think it happened from too many drops and too much hopping. Doing drops and hopping is the kind of thing I like doing, which is why I need stronger cranks. I’m pretty sure my cranks are 152mm. They came installed on the unicycle when I bought it, all I had to do is screw on the pedals. Sorry, but I have no pictures.
unless you invest in something expensive, like kookas, you shall find that all the other [square tapered] crank arms will perform similarly. my suggestion is that you make the investment and buy a splined hub and crank set. i went through six pairs of crank arms on my muni with suzue hub (i am riding the nimbus x’s now). since i usually ride my onza trials now, my muni’s crank arms have had a much needed break. unless you would prefer to dish out 35 bucks every few months for replacement crank arms, get a splined setup.
What part stripped? Did the pedal threads strip (where the pedal screws in to the crank)? Did it start wobbling on the hub?
That’s exactly what happened, the pedal threads stripped.
Then the hops and drops probably had nothing to do with it; you probably used too much torque to tighten the pedals. What kind of wrench did you use?
The use of blue loctite on the pedal threads assures that the pedals won’t unscrew even if you just tighten them until they are snug. There’s not really any need to honk them down real hard.
uni.com is extremely liberal with their returns policy and I’m sure they’d replace them for you under warrantee. It would also be reasonable to assume the liability yourself, based on the above analysis.
If the pedal threads BOTH stripped, one obvious possibility is that you had the cranks on the wrong sides. I made that mistake and the pedals unwound and ruined the thread on one of the cranks.
The threads wind in opposite directions.
I can see no obvious reason why drops would strip the threads.
GREASE GREASE and more GREASE…
If you grease down all threads the chance of stripping anything is greatly deminished. You should have a big tub of grease on your workbench at all times!
Sounds like either the cranks were on the wrong sides, or the pedals were just allowed to be loose while you continued to ride.
Make sure the right-hand threaded crank is on the right side when you ride, and check your pedals every once in a while for tightness. Then they should last until the axle breaks!
And be very careful when threading the pedals in aluminum cranks. The aluminum threads are not as strong as steel threads and they can be stripped if the pedals are threaded on cross-threaded. Cross-threading is where the threads do not sync up properly when you start threading on the pedal. You’re threading the pedal on across the grain. It’s amazingly easy to do.
When you start threading the pedals on you need to use your fingers. Don’t use a wrench. By using your fingers you’ll be able to feel when the threads are lined up and your fingers can’t generate enough force to cross-thread. Use your fingers to get a couple revolutions and then you can use the wrench.
Again, it’s amazingly easy to cross thread a pedal. Especially with aluminum cranks, but it’s also possible with steel cranks. Be careful.
And the pedal threads should be greased.