calling all know-it-mechanics

[rock]

ok so I had a BB like this with a Truvativ Road crank, always thought it was odd that unlike shimano with a 68mm BB shell you used no spacers.

 

http://images1.excelcycle.com/images/D/sram-forc-bb-gxp-det.jpg

 

now I replaced it with this, slightly different looking one

 

http://www.evanscycles.com/product_image/image/689/7be/5a4/51124/product_page/sram-gxp-team-bottom-bracket-cups.jpg

the packaging clearly says to use a spacer on each side (supplied) if you shell is 68mm wide?

 

so what is the correct way to install these BB's now, the newer one does look narrower, but maybe juts cause its more rounded than the more square edged previous model?

 

thanks....

Edited November 8, 2012 by rock

[jannosmit]

try it with a spacer each side, if it doesn't fit, take one out, try again. check front derailer alignment after fitting the crank

[kosmonooit]

Not that I identified with the title, but I feel obliged to share this pearl of wisdom: when in doubt, RTFM!

Edited November 8, 2012 by kosmonooit

[GoLefty!!]

Read the instructions. Truvativ Know how to install the BB.If they say use the supplied spacers on a 68mm shell they're probably right.

The old GXP BB's had rather wide bb cups so the bearing was situated corrected on 68mm. For 73mm you needed to dd the spacers.

The new GXP works more like the Shimano and Chris King BB although the latter requires a GXP conversion kit.

[Baroudeur]

As far as I know you do not use spacers on the road cranksets but can/do on the MTB cranksets.

 

Just built up a road bike with SRAM and the GXP BB instructions said not to use spacers. Have installed everything and it works perfectly so far.

[NotSoBigBen]

Surely spacers or not is a function of the BB width (easy to measure) so if the manual says one on each side then that is it? I have used the old and new style GXP's and they are the same.

[rock]

thanks all, I removed the BB fitted the spacers and when installing the cranks and started to tighten them they were binding and could hardly turn, removed everything, took out the spacers re-fiited everything and cranks tightened up and spinning like never before.......so guy at the shop was right, no spacers for road cranks regardless of BB shell width.......looks cleaner without spacers too......

[rouxtjie]

thanks all, I removed the BB fitted the spacers and when installing the cranks and started to tighten them they were binding and could hardly turn, removed everything, took out the spacers re-fiited everything and cranks tightened up and spinning like never before.......so guy at the shop was right, no spacers for road cranks regardless of BB shell width.......looks cleaner without spacers too......

Just watch the driveside dust seal(if you can call it that), if it starts moving / creeping towards the crankarm it will expose the bearings. If you own a garmin you are sorted. Take one of the "rekkies" that you use to fit your device and double wrap it around the arm, this should keep the seal in place if you use no spacers. It should give you a couple more miles on the GXP BB

[rock]

thanks rouxtjie, I noticed that seal doesn't really stay on......no Garmin I'm afraid, just a setting sun to tell me I've done enough for the day

[rouxtjie]

thanks rouxtjie, I noticed that seal doesn't really stay on......no Garmin I'm afraid, just a setting sun to tell me I've done enough for the day

hehehehehhe, look I suppose a normal rekkie will do, its just to ensure that the worst doesn't get in there.