Ok, so who can tell me the difference between a Shimano BB90-A – here

And a Shimano BB90-B – here

Both seem to be XTR, BSA thread, and 68/73mm width ???

the “A” is at a nicer angle but doesn’t come with spacers ?

the “A” is at a nicer angle but doesn’t come with spacers ?

Well I was expecting some smart@ss to say “one euro”, but your answer was pretty good too 🙂

But, taking your answer more seriously than it was meant, although not shown in the photo, the ‘A’ description does say “3 x Spacer 2,5mm”, so it can’t be the spacers!

IIRC, when I bought one a few months ago, one was for mountain, the other one for road. Though that second picture up there says mountain on the cups, the part number isn’t shown in that angle, so it may not be the ‘B’ version.

I’ll see if I can find some proof.

IIRC, when I bought one a few months ago, one was for mountain, the other one for road. Though that second picture up there says mountain on the cups, the part number isn’t shown in that angle, so it may not be the ‘B’ version.

Hmm, not so sure about that. If you look in the product descriptions linked to above they are both definitely for XTR mountain cranks, and Shimano MTB BBs tend to be labelled BB50, BB70, BB90, whereas the road BBs are labelled BB4500, BB5700, BB6700, BB7900 etc. Like this…

And just to add to my confusion, I’ve now found this one which is simply labelled BB90, without any added ‘A’ or free ‘B’…

Aaaaarg! How can it be so complicated?

I have no solution, but I feel your pain! Finding the correct replacement BB for my Stumpjumper FSR was a right ballache.
BB-91 42A and I never found what the differences were between the different ones.
I think 91 is the shell width, 42 is the diameter for the press-fit but god knows what the A is for….

Ah you may well be correct, I was assuming the numbering convention would be the same for press-fit, which is what I bought, (and I’m sure that’s right, A = mountain, B = road).

Ah you may well be correct, I was assuming the numbering convention would be the same for press-fit, which is what I bought, (and I’m sure that’s right, A = mountain, B = road).

Yes, you’re right, in press-fit the BB91-41A is 89.5/92mm width for MTB, and the BB91-41B is 86.5mm width for road (and as far as I can see the only difference is in the width of the sleeve, and the cups are identical!).

But unfortunately, the external BBs seem to be classified differently… 🙁

So I emailed the retailer selling the A and B, and got this reply…

these articles are similar, A and B are just from other productions

Guess they don’t know either 😆

Yep, they will both disintegrate far to quick…

Yep, they will both disintegrate far to quick…

Yeah, maybe right there. I seem to be averaging about six-twelve months on my Shimano BBs at the moment, which is why I decided to go for the XTR this time in the hope it will last a bit longer than the SLX/XT level I’ve been using up until now (read the XTR is sealed a bit better).

Anyway, at twenty Euros for an XTR BB I’m not too fussed about treating them as a consumable, just like chains, brake pads, tyres etc.

I’ve just had to look into the road BB’s and it seems to get even worse, my FSA BB has given up after about 900Kms and even they do different standards for just their chainsets!

Luckily it’s a warranty job so teh shop can scratch their heads over it next week 🙂

I’ve just had to look into the road BB’s and it seems to get even worse, my FSA BB has given up aftre about 900Kms and even they do different standards for their chainsets!

Luckily it’s a warranty job so teh shop can scratch their heads over it next week

Hey Rich, hows it going? Quiet day in the office? 😀

Going good Andy, only just got in, school assembly this morning 😀

Gotta check the “news” first thing before getting any work done!!

Ha ha, me too, it’s the morning ritual – cup of coffee and check STW!

Hope to see you out on the new Gunjin trails again soon…

Yeah, definitely 🙂

SAint has nice long threads on the driveside

(Whatever you buy, I’d suggest lifting the seals and greasing the shit out of ’em. Works for me)