Re: bearing help please

Hello people,

I agree it's not a good idea to mess with sealed bearings but it
happens that they get dirty and gritty inside when you ride the
unicycle on long trails with mud / dust / wet dirt...Just hold the
wheel closer to your ears and give it a spin (watch out for the
pedals...). If you hear that scratchy sound coming from the bearings
then you might have this problem (let's not talk here about too-tight
bearing caps...) What to do now?

hmmm. if you just ignore this, with time the annoying sound will
eventually disappear but talking with it days from the bearings life!

So, you still might want to service it in this sad scenario. If you do
the cleaning/re-greasing job properly you may get away somehow
better...

see this:
http://tinyurl.com/26j6u

note:
if you get the bearings out of the axle many times (in some cases just
one time means many!) it may slip next time you put it on - so the need
for some Loctite adhesive (609?) or spacers may emerge...

Finally, I would also like to know other opinions from the experienced
ones in this matter - I just don't like when the bearings get
"clogged"...and they do 🙁

Flaviu

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Skate bearings come packed with air and lightly oiled. Their "seal" is a
metal plate retained with a circlip. It is designed to be removed and
oiled periodically with the oil they provide.

Uni bearings come packed with waterproof grease. They are fit with a
precision seal that will be damaged it you pry it off, crating a gap
for water and dirt to enter. The manufacturer does not intend for the
seal to ever be removed, it has no circlip.

Read this info page from SKF, maker of many uni bearings. Pay special
attention to this quote from the second paragraph.

"The bearings with shields or seals on both sides are lubricated for
life and are maintenance-free."- SFK

http://tinyurl.com/28v62x

Also, the way to test a bearing is not to spin the wheel and listen, as
noise may have multi origins. Remove the wheel and rotate the outer
shell of the bearing with your finger. If it turns smoothly without
sticking in spots, it's ok.

I suspect that if you find your bearings go bad after a short dip in
the mud, you may have washed the waterproof grease from around the
bearing seal. Or did you spray them with wd40 ? Note how in the above
short article, they warn not to wash the bearing. A light spray with a
hose should be fine I think, but blasts of soapy water may ruin the
waterproof seal by dissolving the grease around the lip.

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feel the light
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http://tinyurl.com/yp58cu

The type of bearings we use are called "sealed bearings with contact
seals"

Click on the above link, and note that bearings from 25 to 52 mm come
with type RSH seals. (third paragraph) We use 42 mm.

Then go to the bottom and read the last paragraph

"Details regarding the suitability of RSH and RS1 seals for various
operating conditions will be found in table 1."

So click on table one.

Note that type RSH seal are rated excellent for water and dust
exclusion, and grease retention.

But only if you don't bugger them up !🙂

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[quote="feel the light"][url]Note that type RSH seal are rated excellent for water and dust
exclusion, and grease retention.

But only if you don't bugger them up !🙂[/quote]



After my first muddy muni even, my bearings got grit in them, and I
hadn't touched them. It wasn't that it fell into the lake. Replacing
them was definitely the fix.

Another time and unicycle, found some really poor bearing on a new
unicycle, not the most inexpensive model. Was missing the lip that
holds the seal, didn't even have a cover on it. Unicycles are made with
rejected bearings, so you can't count on that excellent quality.

One more thing, Unicycle frames, anything better than entree level
should be made to hold the bearings without crushing them, like the
great KH frames.


--
Chrashing

Regards,
Ken
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Feel the Light - Those are awesome data pages by SKF. Thanks for posting
them.

A few quick questions:
How do you know that we have RSH bearings? I mean the KH bearings on my
unicycles say Qu-Ax 224212-RS. What does the RS and or RSH stand for?

Also can we close the Kris Holm frames all the way until the bearing
cap touches the frame or should we leave a slight little space?

Right now there is about a quarter to half mm crack between my bearing
caps and frame on both my KH unicycles. All three of them seem doing be
doing fine.

Unicorn

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Unicorn said:

Also can we close the Kris Holm frames all the way until the bearing
cap touches the frame or should we leave a slight little space?

My KH 29 frame has the caps touching the frame, the are bolts tight,
there is no drag on the bearings.

--
Chrashing

Regards,
Ken
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Unicorn said:

Feel the Light - Those are awesome data pages by SKF. Thanks for posting
them.

A few quick questions:
How do you know that we have RSH bearings? I mean the KH bearings on my
unicycles say Qu-Ax 224212-RS. What does the RS and or RSH stand for?

Also can we close the Kris Holm frames all the way until the bearing
cap touches the frame or should we leave a slight little space?

Right now there is about a quarter to half mm crack between my bearing
caps and frame on both my KH unicycles. All three of them seem doing be
doing fine.

Unicorn

-RS means "Rubber Sheild", technically the bearing should have -2RS on
it as this means that it has rubber sheilds on both sides.

as for tightness of the bearings....
Please, please, please read the instructions that come with the
unicycle!

If the bearings housings are touching then they are way way too tight
and you will probably have distroyed your bearings. Certainly your
wheel will not be turning smoothly. There should be a gap. The bolts
should be only a little bit above hand tight as the outer bearing
casing are delecate.

Roger

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Hi Roger,

I always post informative leters for the public to read and not as
Private Messages. Thanks for the post.

First of all I got the bearing that I ordered form you very fast. Less
than 5 days after ordering they arrived! That has got to be a record
for both the Israeli and British mail systems! I do not actually need
them right now but I figure that it is good to have a spare set.

I closed my KH bearing caps on all 3 KH models that I have just a tad
bid more than was required so that the wheel did not rattle in the
frame. This left about a half mm space between the flat parts of the
bearing caps and frame. Another quarter to half turn of the bolt would
have brought the bearing caps and the frame in contact. Would this be
to tight? I don't know. It seems like many riders are riding this way
with no bad effect on the bearings. It seems like KH would have
designed his bearing caps and frames to fit snugly against each other.
I figure that I will feel it if the bearings get loose in the holders
and I always have the basic tools to do a quick 20 second tightening.
Therfore I leave the little space. I have written to Kris about posting
the maintenance instructions and technical information on his site. I
got the instructions in German only from MDC.
On my Onza there is a good centimeter space between caps and frame.
this is understandable because they are pressed from CroMoly and are
not forged or CNCed solid aluminum. I think that most people have to be
careful with the CroMoly frames. The KH Aluminum frames at least seem
to be desinged to fit togethr perfectly therefore giving an idiot proof
safeguard against over tightening.

All the Best!

Unicorn

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When I wrote that you must be careful not to tighten the caps down on
MOST unicycles, it was because I, like the rest of us (except Roger),
thought that KH was an exception, and that KH caps could be put on all
the way, with no gap.

So after reading Roger's comments, I flipped over my '07 KH 20 and gave
the wheel a spin. It spun around smoothly, for 4 revs. Seemed ok to
me.

But when I loosened the cap bolts a half turn each and gave the wheel
the same shove, it spun around for 12 revs!

As usual, Roger is right.😎 I also had to loosen the caps a bit on
my 05 KH 24. Oh well, live and learn. I hope they aren't damaged. I'm
real fussy about my motorcycle wheels, and will replace a bearing for
the slightest sticky spot. The uni's don't worry me much. It's not
going to be driven 100 mph ! So I'll just wait until tire change to
check them.

Some of us may be using SFK bearings (UDC sells them). There are many
brands, and they are all pretty similar IMHO. Perhaps, like anything
else, it is possible to find some junk from China or something. If you
can find some in your size, the ones with teflon shields may be
better, but that is just a guess. They seem to cost slightly more.

RS1 means one rubber seal. This is used on motorcycles, where the
unsealed side faces inward to the hub.

RS2 means two rubber seals. I guess SFK's RSH means the same as RS2.

Z means one metal shield and ZZ means 2. I would avoid these, they are
less water resistant then rubber, and cost the same.

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OMG, Even after reading Roger's post I thought KH was and exception to
'carefully snug' tightening the cap bolts. But, with the last post
from 'feel the light' I had to check my KH. The wheel does roll better
with the cap bolts loosened.

I hadn't notice the difference when I put the wheel on the frame. With
the bolts tight it rolled well, but loosen a bit and it coast twice as
far.

Thank you 'Roger' and 'feel the light' for explaining this.

--
Chrashing

Regards,
Ken
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Chrashing said:

OMG, Even after reading Roger's post I thought KH was and exception to
'carefully snug' tightening the cap bolts. But, with the last post
from 'feel the light' I had to check my KH. The wheel does roll better
with the cap bolts loosened.

I hadn't notice the difference when I put the wheel on the frame. With
the bolts tight it rolled well, but loosen a bit and it coast twice as
far.

Thank you 'Roger' and 'feel the light' for explaining this.

I remember Roger telling us this handy bit of information during a
maintenance class at BUC and thinking "That's a really good piece of
advice. I should post that on the forum next chance I get."

And promptly forgot about it.

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