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

and

25x62x17 = 6305

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...