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  1. #1
    Join Date
    Jan 2009
    Location
    in a suite of vigorous disturbances
    Posts
    1,080

    New Chain, new cassette. Rides like dogshit

    3x9 sram setup with a new pg990 cassette and new sram chain.

    replaced chain (overdue) and it was meshing poorly with the cassette. so i got a new cassette and life is good as long as I'm not in the middle ring. (which is not ok...i spent tonight's ride cross chaining)

    So, the middle ring is toast (Raceface Turbine rings on truvativ noir cranks)...but with a new chain is it necessary to replace all three rings if the other two are working fine?

    I'm hoping the answer is "No". just replacing the middle will suffice as long as the other two chainrings are shifting and pedaling ok?

    and that being said...do i have to stick with the same brand (they work fine) or will the ramps work fine with a different brand?

    what says ye?

    ps: anyone have a 32t turbine or similiar?

  2. #2
    Join Date
    Dec 2007
    Location
    Hell Track
    Posts
    5,626
    just replace the middle ring - you'll probably be fine. Worst comes to worst, you'll have to get a new granny (they're cheap). RF ramped rings are fine, as are most other ramped rings that aren't totally bottom of the barrel.

  3. #3
    Join Date
    Mar 2006
    Location
    SLC
    Posts
    1,973
    Since you spend most of your time in the middle it usually wears first. I've had plenty of times where the middle ring was worn and caused the chain to skip, both other rings were fine. Just replace the middle ring and you should be good to go. Replace it with any ramped ring, brand shouldn't matter.

  4. #4
    Join Date
    Oct 2004
    Location
    Pdx
    Posts
    2,724
    No reason to replace the granny and big rings if they are engaging and pedaling without grinding. That said, do look objectively at the amount of sharktoothing on those other rings - unless you spend the vast majority of your riding in the middle ring, I'd be surprised if at least the granny didn't need replacing too.

    You can also run different brands of chainrings on the same crank.

    Edit - looks like my advice matches Toast's and JTrue's. Great minds think alike...

  5. #5
    Join Date
    Dec 2004
    Location
    Tucson, AZ
    Posts
    371
    Interesting, I was always told to keep chainring brands the same. I know on my last set of XTR cranks, (2 gen ago?) the middle ring was cut differently for a 22 and a 24 tooth granny - they needed the 'offramps' on the small to mesh with the 'onramps' of the middle, same from middle to big. So, I said fuckit, and replaced the small/middle with Blackspire, and put a bash on the outside

    Other brands may not have complicated/contrived of a ramping system, but if RF rings are not mucho $, seems easy to just replace it with the same thing.
    Life is tough. It's tougher when you're stupid

  6. #6
    Join Date
    Jul 2005
    Location
    Boulder
    Posts
    5,226
    Shimano has so many patented ramps and designs that I wouldn't be surprised if everything was different.

    "Works well enough" and "optimal" are two different things.

  7. #7
    Join Date
    Mar 2006
    Location
    Missoula, MT
    Posts
    9,715
    Is it dropping off the middle ring?
    Not shifting on the rear end?
    Check you derailleur hangar?
    It's slipping on the middle ring?
    No longer stuck.

  8. #8
    Join Date
    Oct 2002
    Location
    Shadynasty's Jazz Club
    Posts
    6,656
    ^^Yeah, you need more troubleshooting. The fact that it works great except when you're in the middle ring isn't nearly conclusive enough.
    Remind me. We'll send him a red cap and a Speedo.

  9. #9
    Join Date
    Oct 2008
    Location
    Orygun
    Posts
    387
    I've got an extra set of Shimano front chainrings off an xt or lx crankset. They probably have less than 200 miles on them. Little ring looks like it has never seen a chain. If you decide to replace the front rings and want some free rings, shoot me a pm.

  10. #10
    Join Date
    Oct 2004
    Location
    lcc
    Posts
    12,489
    be sure to look at the pulley wheels of the rear derailleur for wear as well. likely culprit as well.

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