Hope bb with sram force chainset

phelim21

I have just replaced my shimano pf30 and 105 11 spd chainset with a hope bb and sram force chainset gxp. This is to go with sram etap. After the bb and chainset were fitted the chain is now catching on inner chainring while in 39/11,12. This didn't happen before with 105 52/36. Any suggestions.

cougie

You're not supposed to use 39*11 - so it's probably doing you a favour ? Cross chaining isn't a great idea and that ratio will be duplicated on your big ring and large sprockets anyway.

phelim21

With sram etap you are supposedto be able use all gears with no cross chain problems

StillGoing

phelim21 wrote:

With sram etap you are supposedto be able use all gears with no cross chain problems

With all SRAM you're supposed to be able to cross chain without interference. You still shouldn't be doing it for anything other than those times when you don't want to change down for a short ramp or change up for a short ease on a climb.

OP, how come you haven't just used a SRAM GXP BB to give you the correct offset?

paulbnix

I have Etap with a GPX SRAM Force chainset running in a Hope BB using the Hope GPX adapter.
Mine is 50/34 rather than your 5?/39.

I think you are saying that in 39/11 the chain catches on the inner side of the large chain wheel.

It seems you need the chainset moving out on the DS. Unfortunately with GPX it's the NDS that locks it in position so remove any spacers you have on the NDS.

phelim21

Thanks will try that.

phelim21

Paul is your gxp shim pressed all the way in.

paulbnix

Yes I believe it is.

Doesn't tightening the NDS bolt push it in because it gets clamped between the 22 - 24 mm shoulder on the axle and the NDS crank.

If yours isn't then it would explain why the DS crank is not far enough out.

step83

as said you just need a pair of GXP adaptors to make it fit, was going to on mine but with a standard GXP instead.
In terms of cross chaining SRAM accept people will do it hence you have things like Yaw on some of the mechs does make life easier in the long run but takes a bit longer to setup. Allows me to use big ring to big ring without any issues.

smiler21

Paul nds is tight. Might try a new chain or bring t back to mechanic.

paulbnix

I had the same problem when I replaced the outer chain ring on an old FSA crankset.
The new ring was not really compatible.
I end up putting some small washers between the inner and outer rings and bolting them back together. It worked well enough for the winter bike.

I'm not suggesting this as a solution to your problem.

Maybe the geometry of your bike causes the issue and it could be that a genuine SRAM GPX BB will work.