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Thread: large rear cog

  1. #1
    Senior Member jpsawyer's Avatar
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    large rear cog

    I have french threaded stronglight cranks that i have been able to get off. i wanted to switch them out so i could get some different gear ratios. something between a 40/16 and a 52/16, the original chainrings that came on the crank. and finding a chainring for these cranks is difficult due to the weird BCD and because it has 3 arms. and recently, i broke the smaller chainring because a stackbolt fell out and it bent. so as i am unable to remove the crank or get new chainrings, i was wondering if there are any advantages/disadvantages to having an 18T or 20T cog in the back and a 52 chainring in front. thanks.

  2. #2
    Veteran Racer TejanoTrackie's Avatar
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    Well, other than the slight increase in weight of the larger cog and longer chain, there is no real downside. The advantage is that a larger cog will last a lot longer and will run a bit smoother.
    What, Me Worry? - Alfred E. Neuman

    Quote Originally Posted by Dcv View Post
    I'd like to think i have as much money as brains.

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    Senior Member Bighec's Avatar
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    Quote Originally Posted by TejanoTrackie View Post
    Well, other than the slight increase in weight of the larger cog and longer chain, there is no real downside. The advantage is that a larger cog will last a lot longer and will run a bit smoother.
    Why is this?

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    Senior Member fixedgear80's Avatar
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    Pedaling force is being applied to a larger surface area. 20 teeth carrying the same amount of force that 16 teeth will last longer.
    Quote Originally Posted by TejanoTrackie View Post
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  5. #5
    Veteran Racer TejanoTrackie's Avatar
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    A larger cog engages more links on the chain, so it distributes the load to more teeth on the cog, reducing the load on individual teeth so they wear slower. It runs smoother because the chain is bent more gradually around the cog.
    What, Me Worry? - Alfred E. Neuman

    Quote Originally Posted by Dcv View Post
    I'd like to think i have as much money as brains.

  6. #6
    Senior Member jpsawyer's Avatar
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    huh. i think i am just going to do this. i do not mind the extra weight and it is the cheapest solution to my problem. thank you very much.

  7. #7
    Senior Member Bighec's Avatar
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    Thanks for the info. Makes perfect sense.

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