Squeaky Semcycle cranks

Squeaky Semcycle cranks

Post by Matthew Macaule » Tue, 04 Jul 2000 04:00:00


Hey all,

I got a new Semcycle (not the XL) last November which I've already
ridden a lot on (several hundred miles). Recently, the place where the
crank is joined to the axel has been squeaking quite loudly (both
cranks). Has anyone else notice this with Sems? I done a fair amount of
kick-up mounts and other abusive tricks, so I'd imagine that puts extra
stress on that part of the uni, but it still should hold up better than
that.

I've tried oiling it, and this hasn't worked. But the problem seems to
be that the axel itself has been over time been worn down and "shaved
down," so the end of it is slightly smaller in diameter than the base.
So I tried hammering the crank further into the axel. This worked for a
few weeks or so, but the squeaking is back. Maybe it just came loose, or
maybe the axel has worn down further.

Is this problem fairly common? I'm a little disappointed in the quality
of this uni (though it was much better than my old Zephyrs!). I'm sure
many of you hotshot riders put a lot more abuse into your Sems than I
do. :-)  Is hammering the crank into the axel the right solution?

Thanks in advance,

Matt Macauley
http://www.tou.com/host/matt

 
 
 

Squeaky Semcycle cranks

Post by unicycleSource » Tue, 04 Jul 2000 04:00:00

Matthew,

I think from your description that you have actually had loose cranks and
they have worn the crank/hub.  They have what is called a Morse taper on
them and this should be identical, it is about 1 degree.

As a general rule you should tighten your cranks as soon as you hear them
creak.  This is a sign that they are moving and any movement in this area
will create wear.

As you have realised kick up mounts do put consider and this is probably the
reason for the loosening.

I would take your cranks off, but mark where you had them on.  Then inspect
the cranks and the hubs.  With luck it is your cranks that have worn, the
Sem hub is one of the better ones about so this hopefully will be the case.
If there is no sign of wear... clean up the surfaces up, oil with a very
light oil or kerosene, then put the cranks back on 90 degrees off from where
they were previously. Use a hammer and a block to put the cranks on tight.
If there is wear on the cranks, don't put them back on, buy new ones, it is
worth it as they will damage the hub in the end!  You can get replacement
cranks relatively cheaply from John Drummond in the USA at
www.Unicycle.Source.Com  If it is your hub and cranks that have worn... you
really need to replace both... or just pop down to your local welder and
weld them up. You have nothing to loose because if you put new cranks on a
worn hub it will ruin them and visa versa.

I hope this has been helpful.

Roger

--------------------------------------------
     The UK's Unicycle Source
   http://www.unicycle.uk.com/
--------------------------------------------

Quote:
----- Original Message -----


Sent: Monday, July 03, 2000 5:50 AM
Subject: Squeaky Semcycle cranks

> Hey all,

> I got a new Semcycle (not the XL) last November which I've already
> ridden a lot on (several hundred miles). Recently, the place where the
> crank is joined to the axel has been squeaking quite loudly (both
> cranks). Has anyone else notice this with Sems? I done a fair amount of
> kick-up mounts and other abusive tricks, so I'd imagine that puts extra
> stress on that part of the uni, but it still should hold up better than
> that.

> I've tried oiling it, and this hasn't worked. But the problem seems to
> be that the axel itself has been over time been worn down and "shaved
> down," so the end of it is slightly smaller in diameter than the base.
> So I tried hammering the crank further into the axel. This worked for a
> few weeks or so, but the squeaking is back. Maybe it just came loose, or
> maybe the axel has worn down further.

> Is this problem fairly common? I'm a little disappointed in the quality
> of this uni (though it was much better than my old Zephyrs!). I'm sure
> many of you hotshot riders put a lot more abuse into your Sems than I
> do. :-)  Is hammering the crank into the axel the right solution?

> Thanks in advance,

> Matt Macauley
> http://www.tou.com/host/matt


 
 
 

Squeaky Semcycle cranks

Post by unicycleSource » Tue, 04 Jul 2000 04:00:00

Opps....

I just realised that I got my own partners url wrong!  :-]

John's Url should be www.unicyclesource.com

I think I am going to have one of those days today, will post about it later
but we (Paul Selwood, Sarah Miller and my self) did the coast to coast this
last weekend in 2 days.  Basically my body doesn't know whether it is coming
or going!

Roger

--------------------------------------------
     The UK's Unicycle Source
   http://www.unicycle.uk.com/
--------------------------------------------

 
 
 

Squeaky Semcycle cranks

Post by Unicycle » Wed, 05 Jul 2000 04:00:00

everything in the previous message is true, but I would like to offer the
following.  

I have made a crank press out of a couple thick peices of maple wood and some
3/4 inch all thread or threaded rod.  I put the all thread through the spokes
and the maple spans across the end of the crank arm and by tightening the nuts
on the allthread I am able to get a great deal of force to bear on the cranks,
pushing them farther onto the hub.  

I bought some black widow cranks from the Unicycle Source which were in fact
better than any others I have used.  They lasted three times as long, and I am
a hard and heavy rider.  But just recently they did wear until the press and
tightening the nuts no longer worked.  Now they are epoxied on.  I put a
punctured piece of visqueen plastic sheeting over the end of the hub to protect
the bearing from the epoxy.  The plastic was tight enough around the hub that
the epoxy could not leak through, and I tore it off after the epoxy cured.  I
cleaned the morse taper with alchohol and covered it with epoxy before
installing the crank.  I also put some epoxy on the bottom of the nut.  Care
must be taken to keep the epoxy from touching the removal threads of the crank.
 The advantage of epoxy over welding is that epoxy can be heated with a propane
torch and softened for removal.  I used system three epoxy because it has a
lower softening point than some of the others even though it is designed for
wood.  It seems to be working fine but I have not actually tried to remove any
cranks that were installed in this way yet.  Heating the cranks to soften the
epoxy may wreck the bearing seals so it may be necessary to replace the
bearings at that point.  This epoxy should be soft enough for removal at 200
degrees faranheit.  My cranks have stayed firm for a week of abuse.

This is a very common problem.  I suppose one remedy would be to buy the
British unicycle with the splined hubs.  DN I think.

Idaho Joe

 
 
 

Squeaky Semcycle cranks

Post by John Chil » Wed, 05 Jul 2000 04:00:00

Wow you've gone hard-core using epoxy to keep the cranks on.

You should be careful when using a press to put the cranks on.  I've heard
tales in one of the bicycling FAQs about people splitting cranks by putting
oil on the taper and then over tightening the crank bolt.  You can also end
up deforming the taper and forcing the crank further on the axle than it was
intended.

I've been using sleeve retainer to hold my cranks on.  Sleeve retainer is
like thread lock but is designed to fill larger gaps than thread lock.  
Sleeve retainer is generally used to secure press fit (metal to metal)
parts.  The grade designed for removable bearings (rather than a permanent
grade) is handy for securing your bearings to the axle and also for securing
your tapered cranks to the axle.  Loctite is one brand that makes a sleeve
retainer but there are others.  However, the stuff is hard to find in a
regular consumer store.  You might be able to find it at a store that
specializes in fasteners.  Industrial supply stores also carry it, but they
usually only do business to business sales (no sales to the regular public).
  Might be able to have your favorite local bike shop order some sleeve
retainer from one of their suppliers.

My muni (using Black Widow Lite cranks), my Coker and a few of my other unis
have had their cranks secured with sleeve retainer.  A little thread lock on
the nut too for good measure to keep that darn nut from vibrating loose.  
Haven't had a crank come loose on me since using the sleeve retainer.  And
when using the sleeve retainer you don't have to force the crank on as
forcefully.  A few light wacks with a *** mallet is good and then tighten
the nut on (but not too tight).  When using the sleeve retainer make sure
the axle and crank tapers are clean and free of oil and other crud before
applying the sleeve retainer.

I haven't had to remove a crank after it has been secured with sleeve
retainer (knock on wood) so I don't know how easy it will be to remove.  The
sleeve retainer and thread lock get weaker when you heat it past some magic
temperature mentioned on the packaging so a little heating with a torch
might be necessary to remove it if it won't come loose using the regular
hand tools.  Hopefully the regular hand tools will be enough.

john_childs

From: (Unicycle17)

Quote:
>everything in the previous message is true, but I would like to offer the
>following.

>I have made a crank press out of a couple thick peices of maple wood and
>some
>3/4 inch all thread or threaded rod.  I put the all thread through the
>spokes
>and the maple spans across the end of the crank arm and by tightening the
>nuts
>on the allthread I am able to get a great deal of force to bear on the
>cranks,
>pushing them farther onto the hub.

>I bought some black widow cranks from the Unicycle Source which were in
>fact
>better than any others I have used.  They lasted three times as long, and I
>am
>a hard and heavy rider.  But just recently they did wear until the press
>and
>tightening the nuts no longer worked.  Now they are epoxied on.  I put a
>punctured piece of visqueen plastic sheeting over the end of the hub to
>protect
>the bearing from the epoxy.  The plastic was tight enough around the hub
>that
>the epoxy could not leak through, and I tore it off after the epoxy cured.  
>I
>cleaned the morse taper with alchohol and covered it with epoxy before
>installing the crank.  I also put some epoxy on the bottom of the nut.  
>Care
>must be taken to keep the epoxy from touching the removal threads of the
>crank.
>  The advantage of epoxy over welding is that epoxy can be heated with a
>propane
>torch and softened for removal.  I used system three epoxy because it has a
>lower softening point than some of the others even though it is designed
>for
>wood.  It seems to be working fine but I have not actually tried to remove
>any
>cranks that were installed in this way yet.  Heating the cranks to soften
>the
>epoxy may wreck the bearing seals so it may be necessary to replace the
>bearings at that point.  This epoxy should be soft enough for removal at
>200
>degrees faranheit.  My cranks have stayed firm for a week of abuse.

>This is a very common problem.  I suppose one remedy would be to buy the
>British unicycle with the splined hubs.  DN I think.

>Idaho Joe

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