Just trying to fit my new cranks and coming stuck. The bb comes with 2 spacers, 1 for each cup when fitting to a 68mm bb shell. Fitted the bb with both spacers and tried to fit the cranks... damn.
The cranks wont go all the way through the bb. There is about 3mm between the drive side bb cup and the crank arm (so you can see 3mm of the axle).
I have checked the frame and it is bang on 68mm, so that's not the problem.
After checking the non drive side cup, i noticed there is a metal sleeve attached the the bearing, that reduces the internal diameter of the bb, which a step in the axle butts up against. I think this sleeve is too long, as it seems to be the only thing stopping the axle going all the way through and it only leaves 10mm of the splines showing in which to attach the non drive side crank.
If someone has a set of GXP bb cups spare and not fitted to a bike, could you do me a favour and measure how long the metal sleeve on the non drive side cup should be?
Thanks very much.
Have you actually tried tightening the other crank arm up, the axle is an interference fit in the sleeve, so may not be quite all the way through.
Tightened the non drive side up as much as i can, still the 3mm gap. I removed the non drive side cup and just fitted the drive side crank with drive side cup. Crank goes all the way through, but then the chainring (using it with just middle ring) hits the chainstay. ARGH!
So the only combination i've got that kind of fits is 1 spacer on non drive side and 2 on drive side (i know this is how shimano ones work, but the truvativ bb only came with the 2 spacers and instructions say 1 spacer each side). This combination leaves only a 1mm gap between crank and drive side bb cup.
Any advice or help?
Cheers folks.
Just a thought, when you look at the BB without the cranks fitted, can you see the actual bearings? If so then you're missing the sealing rings/spacers that cover them, and is probably the cause of your problem.
Nope, the seals and spacers are still there.
Tightened the non drive side up as much as i can, still the 3mm gap.
is there any play if you grab the crank arm and waggle it side to side? They need to be pretty tight.
Also recheck the instructions, there is a table that has a list of which spacers you need to use for various chainlines etc
Have a look at
http://www.hopegb.com/page_mep_force_57.html
That Hope video is the best explanation of how Truvativ Cranks and BBs work that I've ever seen. Certainly better than anything SRAM or Truvativ have ever done!
Was trying to remember as I don't have my bike to hand but I think I remember the same thing when I first put them on my bike. When I looked closely at the axle it is slightly wider at the drive side end, stopping it inserting right into the BB. So there is couple of mm visible. Seams to be the way it is. My BBs have lasted a year each so far. Not great but not bad considering some of the bad reviews ext BBs get.
Thanks for the help and advice. The hope video was pretty useful. When fitted and non drive side is TIGHT, there is no play or wobble in the bb. Looks like the exposed axle is normal. Weird!
Thanks again.