changing rings on modern cranks

Discussion in 'Cycling Equipment' started by JonnyG, Aug 25, 2010.

  1. JonnyG

    JonnyG New Member

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    Hi All: I am trying to decide on the crankset for a new bike build. It will be a 10 speed drivetrain with a compact crankset. The options I'm presently considering are Dura Ace 7950, Campy Centaur, Chorus or Record (11 speed, shimmed for 10 speed if necessary), maybe the Fulcrum RS. I'm not convinced the standard 50/34 rings are quite right for me however, I'd prefer 48/34 or possibly 48/36. None of these cranks seem well suited to changing rings however. The Dura Ace looks particularly unsuited to changing rings so I'm leaning toward the Campy. I have heard that even the Campy won't shift well if the rings get changed. Is this true? I would likely use the TA rings if I made this change.

    Has anybody successfully changed rings on one of these cranks and gotten good / excellent shifting?

    Does Campy make replacement rings in the required sizes (48 outer, 36 inner)?

    Does the Fulcrum crank use Campy rings (110/112 bcd) or standard 110bcd?

    Is the Fulcrum RS and good reliable crank?

    If I did a change like this, should I change both rings even if I only need to change one?

    Thanks
    Jon
     
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  2. swampy1970

    swampy1970 Well-Known Member

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    Chainrings are now designed to be used as a matched set due to different tooth profiles and location of shifting ramps, however this is for maximum shifting performance and it doesn't mean that a 48/34 combo wouldn't work on a 7950 crank... It would but maybe not quite as snappy as the 50/34.

    That said, compared to a chainset from 10 years ago it's still going to shift pretty darn fast.

    At the recent Giro d'Italia many pros ran 53/34 for a couple of the stages and at that race in 2008, Contador ran a 53/34 with a 32 on the rear.

    Given the very small difference in gear roll-out between a 50 and a 48, I'm not sure that you'd really notice a difference out on the road.
     
  3. sitzmark

    sitzmark Member

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    Not sure what Shimano has for ring combos on the x900 series. It's a pretty expensive route to go with the hollow outer ring design. The rings I looked at have a list over $200. Part of my reason for going Sram. Sram has rings designated for 50/34, 50/36, 52/36, and I think 52/38. FSA has (had) similar. Not familiar with current Campy offerings.

    Like swampy1970 said - will work, but if ramped and pinned for a specific mate it won't be as smooth as the designed pairing. A one or two tooth difference isn't earth shattering, but a 52 instead of a 50 may be just what you want to forego an 11t for a 12t cog on the rear and hold ratios slightly tighter in the mid/lower range of the cassette.

    Haven't looked into a 48t lately, but it was a popular 110bcd mtb/hybrid ring so finding one shouldn't be difficult. How it shifts ... well... :)
     
  4. swampy1970

    swampy1970 Well-Known Member

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    Remember that 7900 outer chainrings can cost over $400...

    Proceed with caution...
     
  5. Peter@vecchios

    [email protected] New Member

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    First, you can use a so called '11s' crank on a 10s system w/o shimming the rings. TA makes replacement rings for the odd 110/112 Campagnolo(and Fulcrum, same diameters) and they work well. TA has all the sizes you might want and they are cheaper than Campagnolo rings.

    The best cranks in terms of BB quality and chainring quality are Campagnolo and shimano. FSA, sram, Truvativ..are pretty far down on my list. Again TA rings are Campag/shimano quality.
     
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