Good morning all.

My mate needs to replace the front bearings in his Fulcrum Red Zone 700 29er wheel, 15mm axle.

Looking at Fulcrum tech docs, these are apparently Fulcrum part number RP9-004. Bit of Googling suggests these are 17x30x7 size. A 6903 bearing.

Given the Fulcrum ones don’t appear to be the best, thinking better quality bearing – decent seal and stainless? Any recommendations? 6903-RS or 6903-2RS?

Thanks in advance.

You want 2RS, not just RS as that is only sealed on one side. Look at skf, enduro. Whatever is cheapest. Don’t get Max bearings as they are higher load for frame pivots etc.

Shops – MB Bearings, Simply Bearings, Wych bearings.

Stainless is generally softer than bearing steel, so arguably wont last as long, but bearing steel rusts and can do in no time. Pick your poison based on how they last died.

Enduro are good for wheel bearings NTN are pricy but very good, I buy from kinetic bearings, their prices always work out cheapest when I compare.

Be careful with matching Fulcrum bearings – the seals indicate otherwise but they usually need an 18mm i.d. 18/30/7 bearing which is harder to get hold of in stainless.

Front are rt-004 18×30×7, mr18307 bearings not 6903. Rp9 are for the rear hub.

Just to third the advice to ignore whatever’s written on the bearing seal with Fulcrum wheels, and get some callipers out.

I bought some 6903s last week and didn’t realise they were wrong until the axle wouldn’t fit to replace the ‘61903’ as contrary to what you’ll find written online, they are not the same!

Thanks all – very, very handy.

My fulcrums had seals on only one side to make sure the bearings wore out really really fast, so any correctly specced part should be an upgrade.

Scienceofficer is spot on, there’s no one “best” bearing type for bikes… But I doubt many UK mtb bearings get to live their best lives so stainless is probably the safest choice overall. Standard cromo steel is usually cheaper so that can definitely balance out. Good quality cromo repacked with waterproof grease is maybe the best compromise of all but obviously a bit more hassle

A high quality standard steel bearing with plenty of decent grease is the most durable option out there all other things being equal.

Stainless has a place if you regularly ride in salt water or other highly corrosive substance but for most riders high quality standard steel is the best option.