Bearing type/differences?

[Nobbylad]

Looking at replacing the rear wheel/sprocket carrier bearings and whilst I know the sizes, I'm not entirely sure which suffix to get as even the rubber sealed (RS) bearings seem to come in different formats.

Can anyone advise which is the best option for longevity/closest to OEM?

The bearings in question are

20x47x14 = 6204 (http://simplybearings.co.uk/shop/advanced_search_result.php?osCsid=1d05d30ee8bc186e 0b2ea1da0bdfb0e0&sort=2a&search_in_description=0&keywords=6204&osCsid=1d05d30ee8bc186e0b2ea1da0bdfb0e0&x=0&y=0)

and

25x62x17 = 6305 (http://simplybearings.co.uk/shop/advanced_search_result.php?sort=2a&search_in_description=0&keywords=6305&x=0&y=0)

and the derivatives are a mix of RS, RSR, RSRC3, 2RSH, 2RSHC3, 2RSR, 2RSL....etc

I've searched here and on SVRider but can't find what I'm after.

Thanks!

[yorkie_chris]

If you went for 2RS or 2RSC3 throughout it would not give you any problem.

RS, rubber sealed. 2RS rubber sealed both sides.
RSR rubber seal which is slightly different.
C3, extra clearance for high speed operation
RSL is a low friction seal IIRC

Thats all I remember offhand but they're all on the net.

[Nobbylad]

Yeah... I found a site listing the suffixes, but really wanted to understand which are the best to use i.e would the low friction ones be better for wheels?

[Nobbylad]

I've downloaded the NSK 'abc' of bearings to have a shufty through later on.

In the meantime, would 2RSRC3 bearings suitable for the rear wheel/sprocket carrier?

[flymo]

I've always gone for the rubber sealed, both sides. They cost like 5 quid a piece so not worth worrying about, will probably last longer than you own the bike.

[Nobbylad]

Thanks Mike, I'm just curious about the specific differences between what appears to be the 'standard' rubber sealed (both sides) rs bearings and the rsr ones and whether/ how the extra clearance of the c3 bearings.

Because we're only talking a couple of quid between the different types, so I'd like to get the best I possibly can for what is hopefully a one off replacement job.

Bikes currently on 40k.

[yorkie_chris]

The RS/RSR is a different seal type, I think the trade off is the RSR seals onto a smaller diameter meaning less friction but higher seal speed and lower life. I could be way out on this though.

[flymo]

I think you're right Chris. From memory it also effected rolling resistance, unimportant on a motorbike but important in high speed bearing applications (e.g. drilling spindles, machine tool motors etc)

[embee]

For info, motorbike wheels are not high speed applications, at most they'll do a couple of thousand rpm. Also temperatures are pretty modest and there's no appreciable shaft flexing or bearing misalignment so you don't need bearings with the extra clearances IMO.

(Bearingshop.uk says...)
C3 tells us that the balls have room for expansion if needed between the races of the bearing. They are generally used on electric motors where a cold start up my cause the balls to heat up quickly and expand, which on a standard clearance bearing would cause premature failure.

[yorkie_chris]

That's probably why I've got standard 2RS in there and am not dead yet...

[Spanner Man]

Good morning all.


Motorcycle wheel bearings have been C3 clearance for as long as I can remember.
Despite running at a relatively low speed. They do have a fair bit of load on them, which would also cause them to get warm methinks.

It's worth paying the extra few bob for double rubber sealed bearings. They out last non shielded, or single shielded bearings by quite a margin.

As I've most likely said before, avoid cheapo, & go for Koyo bearings. These seem to out last all of the others.


Cheers.

[Nobbylad]

Thanks for the input/comments, I'm sure some of you might find this interesting...

http://www.nsk.com/services/basicknowledge/manual/abc/

I'm fairly sure the 'budget' 2RS bearings are the same as the NSK 2RSH bearings, however the RSH seems to indicate a sheet steel reinforced contact seal of acrylonitrile-butadiene rubber. Which is gobbledegook to me, but I'm assuming is still fine to use (as it's listed as an equivalent)?

[Nobbylad]

Good morning all.


Motorcycle wheel bearings have been C3 clearance for as long as I can remember.
Despite running at a relatively low speed. They do have a fair bit of load on them, which would also cause them to get warm methinks.

It's worth paying the extra few bob for double rubber sealed bearings. They out last non shielded, or single shielded bearings by quite a margin.

As I've most likely said before, avoid cheapo, & go for Koyo bearings. These seem to out last all of the others.


Cheers.

Hmmm...thanks Stewart, the C3 seem to be the same price anyway, so I'll probably plump for them on the basis that overkill can't harm (in this case)?

standard bearing (http://simplybearings.co.uk/shop/p6275/SKF+62042RSH+Sealed+Deep+Groove+Ball+Bearing+20x47 x14mm/product_info.html)

C3 bearing (http://simplybearings.co.uk/shop/p6276/SKF+62042RSHC3+Sealed+Deep+Groove+Ball+Bearing+20x 47x14mm/product_info.html)


EDIT What C3 means...


C3 Bearings ~ A Brief Explanation

Applications like motorcycle wheels or bicycle wheels do not require C3 rated bearings.
The bore, diameter and width of C3 bearings are identical to the none C3 version.
C3 are exactly the same quality but have a different a purpose.
---------------------------------------------------------------
C3 bearings have additional internal radial clearances to allow expansion in high speed / temperature environments.
Typically suited to hot and high speed environments ( fans, high speed motors etc)
They can feel loose until at running temperature and speed.
They are unsuitable where critical alignment is required from the onset..
Unless the bearing you are replacing specifically says C3 on it then you should not replace it with a C3 bearing.
A rule of thumb is to replace like for like, there is no advantage to a C3 bearing in place of a standard bearing.
They are unsuitable where critical alignment is required from the onset.
Unless the bearing you are replacing specifically says C3 on it then you should not replace it with a C3 bearing.
A rule of thumb is to replace like for like, there is no advantage to a C3 bearing in place of a standard bearing.

[embee]

Interesting (if nerdy) thread. I'm not in the habit of changing bike wheel bearings so I'm more than happy to take Stewart's observations re. the common use of C3 bearings.

As for temps etc, according to the SKF (http://docs-europe.electrocomponents.com/webdocs/0f8e/0900766b80f8e86b.pdf)info the 6204 sealed bearing has a limiting speed of 10k rpm (so bike wheel speeds are low for this at <2k), speed probably has the greatest influence on temp, especially in applications such as electric motors (as per the blurb) starting from cold and going straight to max speed.
Static load limit is 6550N and dynamic load 13500N (each bearing), so even static a pair of bike wheel 6204 bearings are good for 2x6550N, or 1.3tonnes or double that dynamic, so even a wheelie two up doesn't really come close to the capacity. Remember that bike wheels aren't subject to side forces (as in a car) which would increase the bearing loads substantially.
The few wheel bearings I have changed on my own bikes for being rough or noisy have always turned out to be rusty or contaminated inside.

[flymo]

uhu, I used to rebuild CNC machine center motors running at 70,000rpm and these were vital. Standard bearings wouldn't last the day.