Fulcrum wheel bearings

Hi. Just resurrecting this thread. I'm changing the bearings on a set of fulcrum dB wheels and the fronts were 18mm internal but the back seems to have an 18mm on the DS and a 17mm on the NDS!

Agree with comment regarding cycling specific bearings. All my Fulcrum wheels take 6903 (61903) 2rs 17x30x7mm bearings which are readily available in steel, stainless steel or ceramic and very easy to replace (find a video tutorial). One of the reasons I use Fulcrum as well as being bloody good wheels is their easy maintenance. 

I got a set of "ENDURO MR18307LLB-ABEC5 Rubber Sealed Deep Groove Ball Bearing 18x30x7mm" for my Racing 4 DB front (disc) from Simply Bearings for £25 inc vat and P&P.

It was a couple of quid extra for ABEC5 vs ABEC3 so I didn't even care whether it made a difference or not. It took a couple of rides for them to "unstick" (technical term) and since then, they've been excellent.

As others have noted, the reference numbers on the seals of the original bearings are _NOT_ correct, which is total WTF-ery.

Fulcrum are pretty standard bearings.... we keep them in stock...and tend to use Enduro's .... 6000's and 6001's are pretty commonplace.... 61903's are too in the freehubs but....I've seen Fulcrums with 6000's in freehubs too...  Safe Riding

Just Google R5-004 bearings 

In Sheffield I'm lucky enough to live within cycling distance of both the Peak District and City Seals and Bearings. I recently got some replacement bearings for a DT Swiss wheel from them. I just took the old bearings down, all they needed was the code on the outside of the seal to give me the correct replacements (and I'd imagine that if that hadn't been readable, they probably would've got the calipers out and taken some measurements). I don't know how widespread such establishments are (Sheffield's obviously got a strong engineering sector), but well worth visiting if you can find one near to you... supporting local businesses and all that. Also, +1 on a using socket set to drift the old bearings out and the new ones in. I did a bit of research online on bike forums, and found some links to really useful youtube instructional videos. Admittedly, I did then need some help from my more mechanically minded brother to complete the job!

I'll support the comments above- you should find your wheel in the spares catalogues here

https://www.fulcrumwheels.com/en/download-technical-documentation

which will give you the bearing dimensions. If you can afford the time between disassembly and rebuild, you could just measure your bearings- a cheap vernier gauge is fine (they will be a standard size, to a nearest mm)- and buy new from a generic bearing supplier like simplybearings.

If you have just a little mechanical sensitivity, and a socket set, it isnt difficult to devise ways to drift sealed bearings in and out of position. 

Nsk, ntn, fag, skf- all good cartridge bearings - you should hopefully find the size etched on the current bearing - +1 for Hambini.

As far as I'm aware there is no such thing as a cycle specific bearing; they work just as well in a multitude of other applications.  So, to avoid paying the wheel distributors' prices you could just order from someone like qualitybearingsonline.com and have your choice of manufacturer.  You will need to find the dimensions, or at least the serial numbers from your current bearings.

As a matter of interest the knowledgeable engineer and cyclist Hambini (Google him if you don't know his work) is always very complimentary about NSK bearings.

Best of luck.