Is there actually a difference.
Some googling suggests the 61902 are chrome steel, others say it’s just the same?

I need 4 with rubber seal so which ones and where?
Presumably the cheapest are rubbish but how much to pay?
I don’t really want to be pulling the wheel bearings often so I’ll pay a bit more but £25 seems a lot … especially x4

Same bearings

Same dimensions. Now, do you want max compliment? Stainless? Chromium? Ceramic? Hybrid? LLU seals? LLB seals or SRS?

£25 for 4 bearings isn’t that expensive if they’re a quality brand. Or do you mean each? In which case, that’s way too steep.

What was the failure mode of the current ones?

Some bearing info I copied from somewhere….

2rs is standard rubber seals. LLB is two light contact lips in a groove, LLU is two firm contact lips in a groove. SRS is a snap ring on top of the seal.

You just want 2RS. With a 1 or without. Simply Bearings have a decent range. I usually go reasonably cheap, even SKS/FAG etc don’t really last much longer IME.

Same dimensions. Now, do you want max compliment? Stainless? Chromium? Ceramic? Hybrid? LLU seals? LLB seals or SRS?

£25 for 4 bearings isn’t that expensive if they’re a quality brand. Or do you mean each? In which case, that’s way too steep.

What was the failure mode of the current ones?

Failure – bearing inside freewheel seized … it freed up when knocking out but still feels like crap… rusty

The hubs are Novatec D772 it’s a really light hub but not all that strong …hub strength with a 25kg kid riding isn’t a problem but knocking the old bearings out the soft alloy inside probably will be if I repeat multiple times. (Since the wheels have close to £100 worth of spokes at RRP I don’t want to change the hubs i only paid £1 a spoke for CX ray when building but that took a while to buy) anyway point is want to get maximum life out of these wheels and feel knocking the bearings out more than I have to out will not be great ! Especially if I keep using the steel bolt that is just the right diameter …

It’s mid XC season so it would be really crap having to put on a wheel 3x the weight for a race.
Last weekend we rode downhill… perhaps I should have changed wheels… but I don’t think it had anything to do with the failure he didn’t case any jumps badly and he only weighs 25 kg … or 26 with full face and pads

As it happens I picked up a set of spare hubs when superstar did some clearance so I just stuck in the spare freewheel for now. The freehub bearings I pulled where 6902 2RS the ones on the new but later model spares inside the hub itself are EZO made in Japan 6902-2RU. The ones I pulled are NSK with no country on manufacture who I believe also manufactures in china.

I don’t know what bearings are inside the in use hub (my eyes aren’t that good and I didn’t fancy knocking them out with the bolt just to find out) but they are the same diameter my guess is they are the same as the ones in the freewheel just they switched bearing suppliers and bought bearings made and engineered in Japan rather than made in China ? But what does the RU signify ?…

£25 for 4 is fine … £25 each is more than a new hub…. and I can get a new freewheel for £40 … I’d probably pay someone with the right tools to actually install them rather than bodge it.

Now, do you want max compliment? Stainless? Chromium? Ceramic? Hybrid? LLU seals? LLB seals or SRS?

No idea … the ones that last the longest …within reason which I guess goes down to seals, matierial and manufacturing tolerances.

and would you use 2rs for lower shock bearings, or LLB etc, or do wheels and frames require different seals,etc?
given that I dont want to replace them anymore than I have to

In the past, it’s contamination that kills mine so where possible, I’ll get abec 5 for tighter tolerances and then the tightest seals I can, ideally srs. I also pack them with a heavier waterproof grease. That gives me a draggy weather proof bearing. But then again, I’m a 100kg adult, fairly strong and riding for fun and getting very wet and dirty.

If most of the riding is in a cleanish environment, I’d go abec 5 again with an LLB seal and leave the original grease fill alone. That will give you a faster rolling bearing but at the cost of durability against the elements.

Probably what I’d choose

stevextc – Member
…hub strength with a 25kg kid riding isn’t a problem but knocking the old bearings out the soft alloy inside probably will be if I repeat multiple times…

You’re probably doing this, but a little bit of heat can make a big difference in getting a bearing out. Even a rag tired around the hub with boiling water poured over it a few times would make a difference and you wouldn’t have to worry about galling the bearing lands.

You’re probably doing this, but a little bit of heat can make a big difference in getting a bearing out.

Now I feel stupid!

I don’t mind not knowing about bearing designations … but that is pretty obvious for me to have not thought out