bought cheap used unicycle with loose crank arm. how to fix?

I just bought a cheap China factory type 20" unicycle from a guy on craigslist. It’s for my 9 year old son.

When he showed it to me I immediately found the left crank arm was wobbly. I was able to remove it completely with some pliers the guy had. (I didn’t think to bring tools.) Both the square taper spindle and crank arm looked at least somewhat worn from being loose… but how worn I’m not sure how too tell.
I bought it for $20… figuring it wouldn’t be too big a loss.

Is there something I should do to give it the best chance of working?

A. Remove both crank arms and reinstall rotated 90 degrees?
B. Remove both crank arms and reinstall rotated 180 degrees?
C. Remove both crank arms and reinstall on opposite sides (then rotate either seat or wheel)
D. Just tighten the cranks arms as it.
E. Remove bad crank arm and “fix” it or spindle in some way?
F. <insert option here>

Not to derail my own thread, but…
Something was a little fishy about the whole thing too. I asked the guy (a student at a college campus apartment) some questions. He said he tried riding it twice but fell and couldn’t do it. He said he bought it from a friend. I asked what his friend’s name was, thinking I might be learning about another local rider. He said he didn’t know. :thinking: Some friend. I asked if his friend could ride it good. He then said it wasn’t really a friend, it was a guy who was living with him. :thinking: Some roommate. I guess he used to just say “Hey, guy who is living with me… stop eating my Fruity Pebbles.” Maybe it was some kind of one night stand with a guy on a unicycle? I stopped asking questions. I’m wondering if it was stolen… but like I said, it’s a no-name China factory uni with crappy parts, so it’s probably not being missed like a stolen $100+ uni would be.

I would do the full rotation (left-right) and see if that works. Of course then you are risking wrecking the good crank of the bad spindle but it might work.

Pound them on when you instal to get them to deform to fit the spindle.

If the cranks are bottoming out on the taper you could try shimming it with a bit of tinfoil or metal tape. If that does not work and the unicycle is not worth buying new cranks for (they might get wrecked on the worn spindle anyway) I would just weld them on assuming the cranks are steel.

These cranks were only 10 $ last time I checked. 15 $ now.

http://www.unicycle.com/shopping/shopexd.asp?id=179

Still the best deal if you go the new crank route. It’s really a judgment call, if the square taper is really shot new cranks won’t fix it for long, and you will have wasted your $. Often the cranks are aluminum and will get rounded off without rounding the harder steel hub. If that is the case, buy new steel cranks and they should work ok. Just be sure the seat is facing the front (label side) and you must put the left threaded crank on the left side. Usually the parts with be marked L or R.

Because it is being ridden by a child-very light person, perhaps just banging it on with JB weld and tightening it up might work long enough to see if the kid is interested enough to justify a new uni. There is no economically feasible way to fix a shot axle-hub. If the other parts are worth it, we just lace a new hub up to the old wheel. In your case, if the hub axle is really rounded Sask’s suggestion to weld it on seems the best idea.

I did this last night. It worked well.
$20 and a few hours of cleaning and fixing got me (my 9 y.o. son) this:

The rim says “Vigour 2008 Alloy Samson” and is double-walled. Seems pretty nice for a $20 uni. I hope my kid gets interested.

101_0760_small.jpg

So does mine! Exact same text, same blue colour. I wonder who makes these?

It was £40 (about $20) from eBay here in the UK. Mine’s a 24" though and the frame doesn’t look as nice as yours. I found that the spokes got really creaky after a a couple of months of learning, I need to get it booked into the shop to get them tightened. Also one of the cranks kept unscrewing, some threadlocker sorted that out though.

If it’s built anything like mine it will take one heck of a “learner beating” (lots of falls and crashing into stuff, but probably not big jumps or hops). All in all it’s been a great uni for learning, I hope your son enjoys his!

Please recheck your currency conversion.

Yikes! £40 is actually nearly $70. What on earth was I thinking!? :o

Thanks for the tip!

Yeah I put some thread lock on when I tightened them too.

The frame had a bunch of half peeled stickers on it and rust spots. I used a heat gun to remove the stickers, “goo-gone” stickiness remover, and chrome polish. Now it looks brand new.
There was a higher quality sticker on it that I think might have been the manufacturer’s logo. Here is a drawing of what it generally looked like:

Can anyone identify this?

uni logo.jpg

Yes, mine has that sticker on it too. It would be good to find out where these unicycles come from as they’re actually not half bad for the price (especially in your case!).

Here’s the eBay (UK) link I got mine from.

I asked the eBay seller this question:
“Can you tell me the company that makes this unicycle? Thank you!”

The response:
“Hi There, These are our own make, KMS. Many Thanks KMS”

So, I looks like the answer is KMS. Though I don’t see any good KMS unicycle results in a google search.

The box that mine came in has “KMS Distribution Ltd.” on the side, as well as the address (Unit 20 Fanton Hall Farm, off the arterial road, Wickford, Essex SS12 9JF, United Kingdom).

It also came with a really badly translated instruction leaflet, as with all things like this they’re pretty amusing!

“Originated from acrobatics, unicycling is a newly-developed sports event. It is a combination of venturing, skill, beauty, thrilling, and therefore, holds great attraction towards today’s youths who seek new and strange pleasure…”

I scanned it if you’re interested, it’s full of excellent unicycle propaganda!

link

Oh! I got that leaflet before and already posted about it here. I scanned it too. Check out that thread. I even made a T-shirt!! (sort of)

But that was for an eBay purchased unicycle from “Sky Enterprises”
Probably the same factory… different people selling them with different “company” names.

That second Quote made absolutly no sense