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  1. #1
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    sram 10 speed subcompact 32-48?

    I have a sram force 10 speed drivetrain, short cage RD. I am currently using a 12-28 cassette. I would like an easier gear, so was considering going to a 30 or 32 rear cassette, med cage RD.

    I am thinking smaller rings on the front would be more useful for me. Any advise on this concept? any recommended after market rings?

    Thanks

  2. #2
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    What chainrings are you using and what is the BCD of the crank?
    How much easier do you need? Play around with this and see what combinations might work.

    Sheldon Brown's Bicycle Gear Calculator

  3. #3
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    To do this, 90% odds, means a new crankset. Even if it didn't, chainrings are not very economical anyway.


    The smallest standard chainrings a 110BCD standard crank can go or 34T*. It is a geometry problem. To go smaller requires a smaller BCD, which means a new crankset.

    There are many 48/32 and 46/30 cranksets out there to pick from: Praxis (most affordable but still quality), IRD, White Industries, Sugino, FSA.... I run the FSA SLK 46/30 on my groading machine.

    *Praxis sells a 48/32 based on 110BCD...but they accomplished it with some very clever and intricate machining with special crank bolts.
    Last edited by Marc; 03-05-2018 at 05:30 AM.
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  4. #4
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    Thanks, I have a 34-50 setup now. I think a 32-48 would work with 12-28 cassette. I am going to look into the Praxis rings, and I have White Industry hubs so I will check that out also
    Cheers!

  5. #5
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    I think a new 11-32T cassette would get you lower gearing than the new crankset you mention. And even after you factor in the cost of new longer cage derailleur and new chain you will need, it's probably still cheaper than a new crankset.
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein



  6. #6
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    Quote Originally Posted by deadleg View Post
    Thanks, I have a 34-50 setup now. I think a 32-48 would work with 12-28 cassette. I am going to look into the Praxis rings, and I have White Industry hubs so I will check that out also
    Cheers!
    As stated by Marc, unless you know for sure that your cranks will take smaller rings, it's a very high probability that the smallest ring your cranks will fit is already mounted - 34t. You can tell just by looking at the crank/ring interface. If the chain ring bolt holes are as far out on the ring as they will go (chain just about touches crank spider arms when on the small ring) then you can't mount anything smaller.

    You can look up the BCD (bolt circle diameter) of your current cranks and that will tell you whether you can mount anything smaller.

  7. #7
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    Quote Originally Posted by Kerry Irons View Post
    As stated by Marc, unless you know for sure that your cranks will take smaller rings, it's a very high probability that the smallest ring your cranks will fit is already mounted - 34t. You can tell just by looking at the crank/ring interface. If the chain ring bolt holes are as far out on the ring as they will go (chain just about touches crank spider arms when on the small ring) then you can't mount anything smaller.

    You can look up the BCD (bolt circle diameter) of your current cranks and that will tell you whether you can mount anything smaller.
    There is also the issue that if you replace only the small ring, you will have an 18 or 20 tooth drop. That will make shifting clunky at best and may result in a lot of chain drops and chain suck at worst.

    So you will need to replace both rings. The cost of two SRAM Rival rings are about the same as a whole new crankset.
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein



  8. #8
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    Quote Originally Posted by Lombard View Post
    I think a new 11-32T cassette would get you lower gearing than the new crankset you mention. And even after you factor in the cost of new longer cage derailleur and new chain you will need, it's probably still cheaper than a new crankset.
    This. Spend a little more cash for a great upgrade to your bike.

  9. #9
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    Yah, I understand what you guys are saying. My existing rings are old and would need to be replaced anyway. I would need a new crank for smaller rings.
    I have been geeking out, looking at gear charts etc. It looks like a 30/46 would work for me. That gets me low gears, a closer ratio on the rear cassette, lighter setup. I am thinking a FSA carbon crank SL-K, $350. I think the 46-12 would be ok, if not I could go 46-11. Most of our hills are steep enough I am using gravity only most of the time, I don't race, I usually don't like to draft over 30 mph, to dangerous.

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