Noob needs help with removing cranks.

Unicycles and Equipment
1

Hi, guys, i’m from Sevastopol, Ukraine, so forgive me for my english in advance please)
I’m a total noob at unicycling, learning for about a week, so i don’t understand all the system yet.
I’ve broken the thread in my right crank, so now i need to remove it and replace with a new one, or i’ll try to weld the crank with a pedal. The main problem is that it’s impossible to find here unicycle cranks, so i’ll try to use bmx ones.
I have 2 questions: how can i remove the crank? and will the bmx cranks fit?
I made 2 fotos of the crank, here they are:


thanx

2

first of all, your uni has a square taper hub, so just about any bmx square taper crank should fit; however, the right crank will either have a spider/chainwheel, or a way to fit one to it. Some bmx cranks have a little more Q factor on the right side, and while it shouldn’t make much difference I would prefer that they are symmetrical.

It looks like your crank removal threads are jazzed up. It looks like you might have threads enough to use a crank extractor. If you can’t use a crank extractor you will have to be very careful not to damage the frame as you get your old crank off. I used a small bearing puller in a similar situation and it worked, but it was a lot of effort. As I remember I had to modify it a little to tie the arms together so that they wouldn’t pop off the crank. My first suggestion would be to bring it to a bike shop and see what they can do. Unless they are a fairly new shop they should have dealt with this before.

If you have no intention of using the crank arm again, you could ride with it for a bit without a bolt, and it should wander off on it’s own. As soon as you feel it moving, even just a little, stop riding and see if you can pull it off. You don’t want to damage your spindle.

3

thanks a lot
could you please show me which crank extractor i should use? because i surfed up the net and found different types of them. by the way, i’ve broken the thread where pedal goes into crank. the removal thread should be ok)
that’s why i can’t ride without a bolt. my pedal falls out in couple of minutes.

4

Almost any crank extractor should work. http://www.unicycle.com/shopping/shopexd.asp?id=420 is an example that’s probably available locally. Just make sure your crank extractor doesn’t have an ISIS foot.

You may be able to get a bike shop to install a helicoil to fix your existing crank; it might be cheaper than getting new cranks.

Make sure you have the right crank on the right side; the most common reason pedal threads get stripped is from riding the wheel the wrong way.

5

Beware of using 2 left side MTB cranks if your odd & ends shopping for uni cranks

Tholub makes a good point about the crank threads. Also be aware that the cranks are threaded to only go on one side of the hub, so unless there’s an L & R stamp on the BMX cranks themselves, don’t assume they are opposing cranks.

I tried 2 identical Shimano MTB cranks before, and re-tapped a L crank arm to accomodate a right side pedal. This only a temp fix as the integrity of the pedal threads didn’t last very long.

Good Luck!

6

Is the Park CWP-6 Crank Wrench and Puller from UDC a good tool for removing both cotterless and ISIS? I asked a guy at the LBS about crankpullers that can do both square taper and splined, and he said they were no good. But I think he was talking about a different style of puller.

7

It needs an ISIS foot (or an extra insert) to work on ISIS cranks without damaging the crank threads. UDC might ship it with one, if they advertise it as being good for ISIS cranks. (Do not use it without an ISIS foot).

8

Thanks!

9

Thanks!