SRAM Rival chainline issue
iain13ZV5Y2p
Posts: 2
in Workshop
My girlfriend is now riding my old 2008 (ish) Giant TCR Alliance Zero, and I've made a few changes to it to fit and suit her better including bringing the fairly brutal gear ratios down a bit.
It's running 2x10 SRAM Rival and a GXP BB. It was originally 53-39 on a 130 BCD 172.5 chainset, with 12-25 at the back. Firstly I swapped the cassette to a SRAM 11-28 which I'd had in the spares box, it had done about 100 miles on one hilly sportive, and all was well when I fitted it and we ran it with the 53-39 for a while. I then found a NOS (new old stock) Rival Compact chainset on eBay (50-34 110 BCD 170) and fitted it last night, along with a brand new SRAM 10 speed chain.
However, I now have really bad chain rub on the inside edge of the big ring, when running small ring to the smallest 3 or so sprockets on the cassette. Running small to small, the chain is almost trying to shift onto the big ring occasionally. Of course, I'd never run small to small, but with my girlfriend being a novice cyclist it would be better if the drivetrain would at least put up with this occasionally without trying to tear itself apart! This is nothing to do with front mech adjustment...the chain rub is on the inside edge of the big ring, not the mech cage.
It looks as if I either want to somehow move the chainset out, or move the cassette in towards the centreline is possible...however I don't think there's any scope to do this, unless I somehow remove the spacer that goes between the cassette and freehub body, and compensate by adding a spacer between the small cog and the lock ring...but I don't think this is "normal". Or, tinker around with spacers on the BB, however I've read that contrary to some older SRAM product documentation, you should never run spacers on a 68mm shell with a road crankset (although I am sure that one spacer on the drive side would give it the right line!
I can't really find any technical data on the chainline of the new vs old chainset, but as they are both SRAM Rival, 10 speed, GXP BB, I would have hoped it would be a straight swap. There is a slight design difference between the two...the old 53-39 looks like this...
...and the new compact it like this...
Is there any way to resolve this? Thanks in advance!
It's running 2x10 SRAM Rival and a GXP BB. It was originally 53-39 on a 130 BCD 172.5 chainset, with 12-25 at the back. Firstly I swapped the cassette to a SRAM 11-28 which I'd had in the spares box, it had done about 100 miles on one hilly sportive, and all was well when I fitted it and we ran it with the 53-39 for a while. I then found a NOS (new old stock) Rival Compact chainset on eBay (50-34 110 BCD 170) and fitted it last night, along with a brand new SRAM 10 speed chain.
However, I now have really bad chain rub on the inside edge of the big ring, when running small ring to the smallest 3 or so sprockets on the cassette. Running small to small, the chain is almost trying to shift onto the big ring occasionally. Of course, I'd never run small to small, but with my girlfriend being a novice cyclist it would be better if the drivetrain would at least put up with this occasionally without trying to tear itself apart! This is nothing to do with front mech adjustment...the chain rub is on the inside edge of the big ring, not the mech cage.
It looks as if I either want to somehow move the chainset out, or move the cassette in towards the centreline is possible...however I don't think there's any scope to do this, unless I somehow remove the spacer that goes between the cassette and freehub body, and compensate by adding a spacer between the small cog and the lock ring...but I don't think this is "normal". Or, tinker around with spacers on the BB, however I've read that contrary to some older SRAM product documentation, you should never run spacers on a 68mm shell with a road crankset (although I am sure that one spacer on the drive side would give it the right line!
I can't really find any technical data on the chainline of the new vs old chainset, but as they are both SRAM Rival, 10 speed, GXP BB, I would have hoped it would be a straight swap. There is a slight design difference between the two...the old 53-39 looks like this...
...and the new compact it like this...
Is there any way to resolve this? Thanks in advance!
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Comments
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Sorry, just to be clear, there have never been spacers in the BB, the cups are just screwed in as is.0
