Hi guys,

I'm in the process of trying to fix two bike drivetrains right now and I've got a combination of bits that I can't decide what to replace!

First I guess, are external bearing ISIS BB's really worth looking at? Are they all compatible, i.e. Truvativ GXP, FSA MegaEXO, RaceFace X-Type, Shimano ??? From what I can gather a set of cranks comes with an axle in these cases and this axle mates to the bearings of your chosen BB.

Is there a big advantage to going for external bearings over a standard ISIS BB? I guess this comes down to bearing life and BB stiffness. Again, is it really worth it for either of these reasons?

Am I right in thinking that to use external bearing BB's, you need cranks designed for external BB's? The crank arm presumably has a smaller offset to keep a "traditional" q-factor.

I bought a pair of North Shore XS cranks from a mate for my DH bike, and I've just got an SKF BXC300 which I've just fitted them too. Not ridden yet, but looks lovely compared to the purple Cook Bros cranks that came off! I should have gone for the FR or DH version, but too late now.

My XC bike though now needs a new set of cranks, after landing badly off a jump and pulling a pedal out of my crank complete with threads. That bike runs a square taper, so I could stick with that.

the NorthShores are definitely sticking on the DH bike, but I don't think they're compatible with an external bearing BB, right or wrong?

Anyway, that'll do for now. I've been searchin hard for info but can't find anything definitive, any help would be much appreciated!

"First I guess, are external bearing ISIS BB's really worth looking at? Are they all compatible, i.e. Truvativ GXP, FSA MegaEXO, RaceFace X-Type, Shimano"

Right they're not ISIS for a start

FSA do an external bearing ISIS BB but I wouldn't touch it. Stick with your SKF, i've found them to be excellent

touch wood

listen to kato,he knows it all





























;0)

Yeah, I was thinking the whole "integrated crank" might mean they aren't ISIS. Just out of interest, are the interfaces the other external BB's use "ISIS shaped"?

So you reckon Kato, that I should just stick to a pair of SKF BB's, stick the XC on my XC bike with a new set of cranks, and get an FR for the DH bike?

Suits me tbh - anyone disagree?

I run ISIS Turbines on my bike. I had no problems with RF Signature BB's or the SKF i've got at the moment

IMO, i'd stick with the SKF for now and see how you get on. Bearing in mind the bearing life in external BB chainsets isn't much better anyway