bearing holders

bearing holders

Post by John Chil » Mon, 13 Nov 2000 04:00:00


Lollypop bearing holders are bad

Taiwanese main cap bearing holders like on the Coker, Semcycle XL, Torker
and others are OK

Miyata bearing holders are good

Machined main cap (or pillow block) bearing holders like on the DM's,
Telford and others are good

One thing to be careful about with the main cap style (and especially the
Taiwanese style) is to make sure you don't over tighten them.  It is very
easy to over tighten the Taiwanese style and cause the bearing not to spin
very well.

john_childs

Quote:
>From: jeff d tuttle

>Hello all,
>I still haven't decided for my next unicycle so my question is, is
>it better to have lollipop or the main-cap style bearing holders?
>thanks,
>jeff

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bearing holders

Post by Roge » Mon, 13 Nov 2000 04:00:00

John,

I would have said that saying that lollypop bearing holders are bad, is
being a little simplistic.....

Lollypop bearing are the best for learners.  They are almost fail safe to
assemble.  They tend not fail unless you go into serious jumping (I must say
that this is the ones sold in the UK - we have had zero failures of the
Taiwanese Lollypop bearing holders and the new style Pashleys). Because the
bearings are held correctly they also last longer - again I have had to
replace zero while in the same time I have had to replace a vast number of
bearing with split bearing holders of the same age.

Split bearing housings do come in 2 types.... the machined ones like the DM
and the Telford are superb and the pressed steel ones which are less good.
The problem with the pressed steel ones is the tolerances are often very
poor.  This means that you have uneven force on the bearings and this causes
the bearing to have a shorter life.  This added to the problem in people
over tightening them means that bearing do fail relatively often.  One of my
first tasks at open workshops is checking the peoples unicycles and almost
always there are some bearing holders that are over tight.

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


Sent: Sunday, November 12, 2000 8:37 AM
Subject: Re: bearing holders

> Lollypop bearing holders are bad

> Taiwanese main cap bearing holders like on the Coker, Semcycle XL, Torker
> and others are OK

> Miyata bearing holders are good

> Machined main cap (or pillow block) bearing holders like on the DM's,
> Telford and others are good

> One thing to be careful about with the main cap style (and especially the
> Taiwanese style) is to make sure you don't over tighten them.  It is very
> easy to over tighten the Taiwanese style and cause the bearing not to spin
> very well.

> john_childs

> >From: jeff d tuttle

> >Hello all,
> >I still haven't decided for my next unicycle so my question is, is
> >it better to have lollipop or the main-cap style bearing holders?
> >thanks,
> >jeff

> _________________________________________________________________________
> Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

> Share information about yourself, create your own public profile at
> http://profiles.msn.com.


 
 
 

bearing holders

Post by Rick Bisse » Mon, 13 Nov 2000 04:00:00


Quote:
>One of my
>first tasks at open workshops is checking the peoples unicycles and almost
>always there are some bearing holders that are over tight.

Roger, how do you go about checking them for this problem?

-Rick

 
 
 

bearing holders

Post by Roge » Mon, 13 Nov 2000 04:00:00

Turn the unicycle upside down and spin the wheel.  If it grouches or does
not spin easily the bearing are more than likely over tight.  Quarter turn
on each nut normally does it.

Hope this helps.

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

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


Sent: Sunday, November 12, 2000 3:30 PM
Subject: Re: bearing holders


> >One of my
> >first tasks at open workshops is checking the peoples unicycles and
almost
> >always there are some bearing holders that are over tight.

> Roger, how do you go about checking them for this problem?

> -Rick

 
 
 

bearing holders

Post by John Chil » Tue, 14 Nov 2000 04:00:00

Yeah.  That statement about lollypop bearing holders being bad did deserve
an explanation.  But I was too lazy at the time to write a longer message.

I've had bad experiences with the lollypop bearing holders on my Pashley
MUni.  One of the bearing holders was not machined out accurately and
squeezes the bearing too tightly.  That one bearing starts to spin a bit
rough after about a month of riding and wears out much faster than the other
bearing.  Next time I replace the bearing I might take it to a machinist to
get it cleaned up.  I've been hesitant to attempt to grind it out myself
because I would most likely end up making it worse by grinding out too much
or grinding out the wrong area.  The good news is that I've gotten some good
practice in replacing bearings on the Pashley.

Granted, my opinion is based on a sample size of one.  Maybe I'm the only
one who has a bad lollypop bearing holder.

If the lollypop style bearing holders are machined accurately they can be a
good design.  However, if you are unlucky and get one that wasn't machined
accurately then you are SOL.  Given the general level of quality control on
the unicycles that use the lollypop style I don't have a lot of confidence
in them being able to accurately and consistently machine the bearing
holders.  At least with the main cap style bearing holder you can easily
adjust them if the bearing is binding.

I do agree that many riders who are unfamiliar with bicycle maintenance
probably over tighten the bolts on the main cap style bearing holders.  A
little note about that problem of over tightening should be in the owners
manual for the unicycle, but I have not seen that type of info in any owners
manual for any unicycle.

The Taiwanese style main cap bearing holders do have problems.  They are
more oval than round and they only contact the bearing in a few places.  
This practically guarantees that the bearing will be squished.  Not over
tightening them just means that they are squished less.  When you put your
weight on the uni all that weight it concentrated on only a few spots on the
bearing rather than being distributed evenly across the top of the bearing.  
But for the price range that the Taiwanese main cap style is aimed at I
think it is an OK design.

Assuming a well machined lollypop bearing holder the lollypop style will be
easier on the bearings and the bearings should last longer than in a
Taiwanese main cap style.  But if you are going for long bearing life I
think the Miyata and the machined pillow block / split block bearing holders
are the best choice.

john_childs

Quote:
>From: "Roger"

>John,

>I would have said that saying that lollypop bearing holders are bad, is
>being a little simplistic.....

[snip]
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bearing holders

Post by John Fo » Tue, 14 Nov 2000 04:00:00

I read the original question and all the responses so far. Great information
and advice! But nobody mentioned what I consider the main problem with the
lollypop bearing holders on cheap Taiwan and China unicycles.

The problem is not at the bearing. Cheap Lollypop bearing holders are
probably much better on bearings than the pressed steel main cap type. But
if they cause your unicycle *frame* to fail, they can't be recommended. And
they do.

I have heard of many cases of the side-bolted lollypop bearing holders
over-stressing and breaking the metal between the two bolt holes, killing
the fork. This is due to what can most quickly be summed up as retarded
engineering. If you look at automobile and bicycle design, you will never,
ever see flat-headed bolts screwed into non-flat surfaces. At least not
without a specially shaped washer to fit between them. Instead, the force is
concentrated over a narrow, straight line up the side of the fork.

If you don't keep the bolts tight enough, they will come loose because the
bearing holder is not a precise fit into the fork. If you keep the bolts too
tight, eventually the cracking and failure can happen. I imagine the
cracking can also happen from riding with a loose bearing holder, causing it
to jiggle around in there.

The problem can be solved on unicycles with this design with the addition of
washers that are round on one side to match the fork, and flat on the other
side to match the bolt. The reason the cycles don't come with this is
because the manufacturers are working hard to keep costs as low as possible
and keep the unicycles' price down. Buyers don't know (unless we keep
speaking up), until much later if the thing fails. The manufacturers are
*** on a low percentage of these unicycles being actually ridden, and
an even lower percentage of them being ridden enough to lead to these kinds
of problems.

But it's not a total disaster, even if your frame fails. I met a guy this
Spring at Paramount's Great America theme park in Santa Clara. He was a
juggling performer with a unicycle. I checked out his unicycle, and it was
one of the Taiwan models with the lollypops. I was reluctant to tell him the
bad news after riding his cycle around for a few seconds. The frame was
already cracking apart between the bolts, and the bearing holders were
moving around freely in the non-fitting fork ends. It looked like he would
need a new unicycle.

But then I met the guy again this Fall at the Lodi Juggling Festival (sorry
I can't remember his name). He still had the same unicycle. "Why did you buy
another one of those?" I asked him, assuming it was because he couldn't
afford a more expensive one. He replied "I didn't. My bike shop replaced the
fork at no cost." Very cool!

I don't assume all bike shops would do that, but I recommend you try it if
you have the same problem. If lots of returns start being made, the effect
will eventually be felt back at the factory. Then maybe they will consider a
less stupid design.

Until then, I'll have to keep recommending other bearing attachment methods.
Note: The above does *not* apply to Pashleys. I have never heard of a frame
failure on one of those, and the bolt presses on both sides of the fork, not
just one.

In summary, lollypop bearing holders are a great way to hold a bearing, but
if they're not attached to the unicycle fork in such a potentially damaging
way, I can't recommend them.

Quote:
> I do agree that many riders who are unfamiliar with bicycle
> maintenance probably over tighten the bolts on the main cap
> style bearing holders.  A little note about that problem of
> over tightening should be in the owners manual for the
> unicycle, but I have not seen that type of info in any
> owners manual for any unicycle.

You've seen owners manuals for unicycles? I think I have only seen them for
Schwinn and Miyata. In other cases I have sometimes seen poorly translated
assembly instructions (if they used any words at all). And these are aimed
at bike shop mechanics, not consumers at home. No instructions are given on
bearings, or any other part of the unicycles we're talking about, other than
which piece attaches to which other one, and where.

MAIN CAP BEARINGS:
Follow the suggestions the guys have made. Turn the unicycle upside down and
spin the wheel slowly. It should keep spinning for a while. If there is
obvious binding or the wheel stops after a turn or two, loosen the bolts a
quarter turn, as Roger Davies suggested.

Also, make sure you have something in place to keep you from losing your
bolts if they come loose. Lock washers, or those nuts with the nylon inside
to keep them from unscrewing are even better.

TAIWAN/CHINA LOLLYPOP BEARINGS:
Short term: Check the tightness of the bolts and check for movement of the
bearing holder in the frame. I can't recommend a torque setting, but you
also don't want it too tight. Lock washers won't work on the non-flat
surface. Check tightness frequently.

Long term: Find yourself some washers, as described above, that are flat on
one side and round (to fit the fork) on the other side. Brett Bymaster had a
set of these made for his Pashley when it was new, and he's never had any
problems. I have mentioned the idea to John Drummond at Unicycle Source, and
I think he will have a big batch made so they will be very cheap.

Stay on top,
John Foss, the Uni-Cyclone
http://SportToday.org/

"Sometimes there just aren't enough rocks." -- Forrest Gump

 
 
 

bearing holders

Post by Sarah Mille » Tue, 14 Nov 2000 04:00:00

Quote:

> You've seen owners manuals for unicycles? I think I have only seen them for
> Schwinn and Miyata. In other cases I have sometimes seen poorly translated

You shoud take a look at the coker instruction manual, its a
hoot. Especially the many times it warns of danger of death ( or something
like that).

sarah

 
 
 

bearing holders

Post by Staffan Pa » Thu, 16 Nov 2000 04:00:00

John Foss Wrote:

Quote:
> The problem is not at the bearing. Cheap Lollypop bearing holders are
> probably much better on bearings than the pressed steel main cap type. But
> if they cause your unicycle *frame* to fail, they can't be recommended. And
> they do

Yes, I've experienced that the hard way. My first and so far only unicycle
is a cheap 24" Cyclepro from Taiwan  (Warning: stay of this "comfortable as a brick"-seat)

After less than two months of not-so-frequent unicycling,
my rim was slowly cracking up around the "lollipop screws".
I had not been very rough, but at the time i was learning to hop around and going down stairs.

So far riding normally was no problem, but when i grabbed my seat to start hopping,
I ripped the fork straight out of the lollipop holders.
There I stood on what had suddenly become an ulimate-wheel. (Looking very confused, I guess.)

  "Boring technical part:"
I fixed my frame by cutting off about 5cm of the broken fork at each side.
Then I replaced this part with a very durable steeltube
(cut out of steelblocks normally used for making industrial machinery)
I made the hole in one end big enought to be thread outside the (new) forkend,
the inside of the bottom half had the width of the original fork.

After repairing my fork, I have had no bearing problems at all.
The design have lived through som rough Muniing, but now the frame is getting more and more bent...

Happy Uniing  // Staffan Palm
                 Sweden

 
 
 

bearing holders

Post by Greg Hous » Thu, 16 Nov 2000 04:00:00

Quote:

>John Foss Wrote:
>> The problem is not at the bearing. Cheap Lollypop bearing holders are
>> probably much better on bearings than the pressed steel main cap type. But
>> if they cause your unicycle *frame* to fail, they can't be recommended. And
>> they do

>Yes, I've experienced that the hard way. My first and so far only unicycle
>is a cheap 24" Cyclepro from Taiwan  (Warning: stay of this "comfortable as a brick"-seat)

>After less than two months of not-so-frequent unicycling,
>my rim was slowly cracking up around the "lollipop screws".
>I had not been very rough, but at the time i was learning to hop around and going down stairs.

That sounds like it was defective if it happened that quickly. I had my 24"
Summit (basically the same as the cyclepro) for over a year and never had a
problem.  

However, my friend that bought it from me managed to do the same thing (cracked
both sides of the frame around the bearing holder screws) in about 3 months. He
had a local shop weld it back together

I wonder if the dealer you bought the unicycle at would replace the frame,
given that it wasn't that old?

Greg