Bottom Bracket for the big boys

[jeepingeek]

Ok, on my 11 S Stumpjumper 9er ive been through three of the GXP bottom brackets.

What have you guys been using?

[jonshonda]

I also had bad luck with GXP bb's. I would suggest you face and chase your bb before spending money on a new one.

Hope or Chris King should be your best options.

[masonmoa]

Yep, just replaced my GXP in Sep. Went with a Chris King.

[cautery]

I have used many different brands of BBs, I dig outboard BBS... With the right tool (see RWS), you can replace the bearings in the cups instead of buying a new BB assembly, and Enduro bearings makes a great replacement no matter what your budget (Zero if you can swing it.)

NOW... as a former big Clyde and now a barely Clyde, I have switched to the Enduro XD-15 BB...

MOST modern BBs use cartridge bearings, which are not particularly fond of axial loading... which BBs routinely see in MTB. Putting axial stress on a cartridge bearing is not a good thing.

The XD-15 uses a bearing that gives you the friction benefits of a hybrid ceramic cartridge bearing and the axial load stability that you would get from a true conical bearing... (there is a reason that Shimano uses conical bearings in many of their hubs... they are VERY durable)

Now... the XD-15 is NOT a "fire and forget" part... You can't just throw it in there and get max performance out of it...

The XD-15 needs to be torqued JUST to the point that you eliminate all lateral play... That yields perfect placement of the balls on the races with minimal friction.

Now... you ALSO have to achieve a minimum torque on your crank bolt to insure that your crank arms stay tight...

The KEY to having a sh!t-hot performing BB/crank setup with super low friction and all but bullet proof endurance, is to arrive AT your crank bolt minimum torque at the same instant you also JUST reduce BB lateral movement to ZERO. This requires some patience and mechanical skills/logic.

Basically, you need to provide custom spacer setup in the BB installation to achieve this... You can do this in TWO ways...

1) adjust the spacing between the cups and the BB shell (assuming you have a 68 mm BB shell). I haven't set up a 73 mm BB shell install yet). This is the way to go to make the "gross" adjustment (meaning the biggest amount). This is especially the way to go if you need/want to custom tune your chain line.... which I HIGHLY recommend... nothing better than a custom tuned chainline for eliminating those pesky shifting problems)

Best way to do the adjustments here is to have EXTRA 2.5 mm BB spacers... I took a bunch of my extras I had laying around, and machined/lapped them down to the desired/required thicknesses)

2) You can adjust the spacer/shim thickness between the crank arm and the outer bearing race. This is a great place to do your close tolerance adjustments (say you need to increase or reduce torque by just a few Nm or so to get in spec.) I used the included spacers, but I am also getting a collection of peel to fit shims (for setup), and a collection of various thicknesses of single-piece shims for my workbench... for future installs.

A. If you reach crank arm torque before eliminating lateral play, then you increase the shim stack. (Add shims either between the cup and shell or between the arm and outer race... location depends on what give YOU the best result... do whatever improves your chainline (drive side), or keeps it the same (non-drive side).

B. If you eliminate lateral play before achieving crank arm torque spec, you need to reduce the shim stack (either remove a spacer/shim from somewhere, or machine/lap a spacer's thickness down... again, location of the change depends on where you need it.)

I know... sounds like a lot of trouble, but it isn't... and it IS worth the effort.

It took me about an hour for the initial setup, and two additional rides and adjustments to get everything settled in... but...

1) I have zero lateral play and am right at the crank arm torque spec...
2) I have a procedure where I measure BB friction with a "spin test". My RaceFace BB gave me a 9 revolution measurement; my SRAM GXP gave me a 7 revolution measurement.... My XD-15 BB after proper setup gives me a 17+ revolution measurement... a SIGNIFICANT friction reduction, and rock solid lateral and axial stability.

I can't say enough positive stuff about the XD-15... I will never use anything else. AND they have other types... BB30, PF30, et al...

[NYrr496]

Chris King here. Been on the bike for a few years now.

[sundowner]

King, just like the hubs and headset with proper care will last a few frames.

[29erBob]

Try Enduro bearings from Real World Cycling in Tucson. I replaced the BB92 in my Pivot with one a while back and it's been better than the XTR that came in the bike.