cranks and axles - problems

cranks and axles - problems

Post by Wayne van Wij » Wed, 25 Mar 1998 04:00:00


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

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

 
 
 

cranks and axles - problems

Post by P. P. Pucke » Wed, 25 Mar 1998 04:00:00


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

Care to name the company?

--
K. T. Puckett                                                 revolution earth

 
 
 

cranks and axles - problems

Post by Chris A Reed » Wed, 25 Mar 1998 04:00:00

Quote:
>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

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cranks and axles - problems

Post by Chris A Reed » Wed, 25 Mar 1998 04:00:00


writes:

Quote:
>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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