I just bought one of these - http://www.chainreactioncycles.com/Models.aspx?ModelID=55200 - and thought I'd use the lovely, brand new, XTR BB I had spare...
After some trial and error fitting it appears the cranks only work with the GXP BB.
Am I doing something wrong??
In addition, there's an approx. 7mm gap between the crank inner face (on the drive side) and the face of the GXP BB, suggesting that the cranks has an interference fit as you tighten them up.
I've done a couple of rides with them on and no complaints so far, just quite different to Shimano and Race Face that I'm used to.
Any knowledgeable bods out there??
Cheers
They'll only work with a GXP BB although you can use a Hope HT II one with an adapter - see the video below. Which is good as I've found GXP BBs to be rubbish.
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Thanks Paulio, wish I new that before I bought them!
As above bin the gxp bb as they are rubbish.
I fitted a hope one 2 months ago an it's just perfect and already lasted longer than ye second SRAM one did
GXP needs an exact fit of 68 or 73mm shell or the bearings will be overloaded or will float.
Measure your bare shell and be prepared to 'face' it if oversized.
If undersized, you may need to 'face' it to 67 or 72 and fit a 1mm spacer.
Alternatively, get a Shimano which is shell-size tolerant as you preload on the splines.
Sorry to seem negative, but I have both types and GXP works OK for me after I sussed the differences.
PaulD
Paul, you seem to have GXP confused with Race Face. GXP has a stepped axle that clamps the non-driveside bearing with the crank, the axle is then able to float in the driveside bearing, preventing them being preloaded to an early death(no help required for that).
Coatsey,
I have Shimano external and Truvativ GXP.
I truly know the difference.
GXP will crush the bearings if the BB is oversized as it clamps the left crank to the axle with no width allowance. If the shell is undersized, it can all float and let the muck get behind the bearing caps.
Shimano is different. The axle has splines that allow the left arm to fit the BB using the preload nut. It is superior in as much as it is the lesser of 2 weevils.
By choice, on my best bikes I have Ti square taper and Sugino Mighty 900 cranks. Bombproof in my hands/feet.
PaulD
GXP will crush the bearings if the BB is oversized as it clamps the left crank to the axle with no width allowance.
not true. axle is stepped at width of NDS bearing, so all you tighten is crank arm onto NDS inner bearing race. DS bearing 'floats' over non stepped DS side of axle, thus no binding.
it also means that the NDS bearing holds ALL the side loading on it's own, thus dies first.
Tracknicko is 100percent, the gxp is tolerant of a massive range. There is about 10mm of side float on my mates one I have just been fixing.
Tracknicko is 100percent
woowooooooooo!
what tracknico said is right, the NDS bearing deals with up/down left/right loads and the DS bearing floats o only deals with up/down loads, the supposed advantage is that it's under more load from the drivetrain so you're spreading the loads better between both sides.
In reality the BB's are cack and can't be re-fitted with better bearings easily, although BETD do free fitting of their bearing kits wich is probably cheeper than Hope but without blingy anodising of the hope ones.
Are you sure you tightened them up properly, 7-10mm sounds like a lot, not missing the 3x2.5mm BB spacers, mines only got a mm or two.
7-10mm is what is on the one I have here too.
yeh all (five or so) of mine have a fair bit of spare axle on the DS. not sure it's a problem as such...
Cheers all, interesting take from Truvativ if actioned through crappy bearings! I've bought those Hope spacers now to solve the problem.
thisisnotaspoon, maybe my initial analysis of 7mm was too great, more like 4-5mm max gap. It's a 73mm shell. Definitely tightened to the correct tolerance, after a couple of hard rides it hasn't budged and the 'gap' has stayed constant.
Thanks again
My GXP BB lasted hardly any time at all but the Hope with adaptor has been going strong for a couple of years on my lone MTB.
Ok hope adaptor link? I can't find it..
The Hope adaptors won't work with Shimano BB's, only Hope. Shimano have the plastic top hat in the way.
http://www.chainreactioncycles.com/Models.aspx?ModelID=26899
£9
then you just need a hope bb for... £53.99
so £60.
and the sram gxp team bb is £20. and is pretty good compared to the old one... last reasonably well.
false economy IMO.
The shim/ reducer/ adapter that you already have in the GXP BB can be reused, have a look at : steps 8,9,10 etc you do not need the fancy tools.
The tophat in the Shimano BB can be modified / cut to fit.
How much better are the newer GXP BBs compared to the older ones? So far my Hope BB has lasted for about twenty times as many riding hours as the original!