cranks and axles - problems

On Tue, 24 Mar 1998 17:19:42 +1000 “Wayne van Wijk”
<wvanwijk@gil.com.au> writes:
>I recently bought another 24" unicycle. It is not the normal Taiwanese model
>but does come from Taiwan. It looks suspiciously like my 20" Sem XL, especially
>the bearing unit.
>
>After 1 week of moderate use the whole crank arm fell off. The bolt had sheared
>off the thread on the axle/hub.
>
>Apparently (according to a nearby engineer who was standing next to me at the
>time of the accident) it was due to a mis-matched crank and hub. He said the
>nut holding your crank on should spin down with a minimum of 3 full rotations
>to give full strength. The hole in the crank was too small and did not allow
>the crank to go far enough onto the hub for the bolt to hold.
>
>The company whom I bought it from replaced the uni at no charge due to faulty
>product. Nice guys (they paid freight too).
>
>NOW THE PROBLEM BEGINS…
>
>I purchased 2 sets of cranks and a spare hub from the same company with the
>intention of putting short cranks onto my 24" and also making a 26" Muni.
>
>None of the holes in the new cranks are big enough to properly fit the hub of
>my current 24" OR the spare hub that I bought. As I don’t want the same problem
>that I had the first time round is there a way of enlarging the square, tapered
>holes in the cranks so that they will fit properly?
>
>Any help or advice here would be greatly appreciated,
>
>thanks in advance,
>
>Wayne van Wijk

Wayne, this is exactly the problem I had when I went to put 170mm aluminum
bicycle cranks onto a Zephyr that we were beefing up to a 26" Muni. The Crank
wouldn’t go on more than about half a turn. Don’t know what people are thinking
making two sizes of spindles. What I finally did was take the round (square
would probably work better) chainsaw sharpening file that I had and I filed out
the square hole in the crank. Now I only filed TWO sides of it. I figured
leaving the other two sides the way were would ensure that the crank would still
sit straight on the spindle when I was done. Once I got it filed enough that the
nut would go on at least half way by hand, then I got out the ratchet and
cranked it down a few more turns and it ended up about where it ought to be–
with the nut and bolt just about even. I’ve had to tighten it a time or two
since, probably from it “settling” as it smashes down the alum. to fit properly.
But I’m not scared of stripping it anymore. Seems to have worked well. I’m not
sure where Zephyr comes from. I suspect Tiawan, but I’m not sure. Good machine,
though. Chris


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I recently bought another 24" unicycle. It is not the normal Taiwanese model but
does come from Taiwan. It looks suspiciously like my 20" Sem XL, especially the
bearing unit.

After 1 week of moderate use the whole crank arm fell off. The bolt had sheared
off the thread on the axle/hub.

Apparently (according to a nearby engineer who was standing next to me at the
time of the accident) it was due to a mis-matched crank and hub. He said the nut
holding your crank on should spin down with a minimum of 3 full rotations to
give full strength. The hole in the crank was too small and did not allow the
crank to go far enough onto the hub for the bolt to hold.

The company whom I bought it from replaced the uni at no charge due to faulty
product. Nice guys (they paid freight too).

NOW THE PROBLEM BEGINS…

I purchased 2 sets of cranks and a spare hub from the same company with the
intention of putting short cranks onto my 24" and also making a 26" Muni.

None of the holes in the new cranks are big enough to properly fit the hub of my
current 24" OR the spare hub that I bought. As I don’t want the same problem
that I had the first time round is there a way of enlarging the square, tapered
holes in the cranks so that they will fit properly?

Any help or advice here would be greatly appreciated,

thanks in advance,

Wayne van Wijk wvanwijk@gil.com.au

Whoever loves money never has money enough; whoever loves wealth is never
satisfied with his income.

Re: cranks and axles - problems

>None of the holes in the new cranks are big enough to properly fit the hub of
>my current 24" OR the spare hub that I bought. As I don’t want the same problem
>that I had the first time round is there a way of enlarging the square, tapered
>holes in the cranks so that they will fit properly?

By the way, file two ADJACENT sides. Just decide if you want your crank a bit
(itty bitty bit) longer or shorter, and do them both the same. Chris


You don’t need to buy Internet access to use free Internet e-mail. Get
completely free e-mail from Juno at http://www.juno.com Or call Juno at (800)
654-JUNO [654-5866]