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  1. #1
    Senior Member Sincitycycler's Avatar
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    Big chainring/ big rear cog seems to be more powerful!

    I finally installed a 60t Vuelta front chainring with a 20t rear which is 78.8 gear inches. I previously had a 48x16 - 78.8 gear inches before. Used a 1/8" BMX chains on both combos.

    My personal evaluation:

    1.) The 60tx20t is whisper quiet and I seem to generated more torque, especially on moderate drags. I'm sure it's due to the fact that the larger diameter rear cog of the 20t vs. the 16t is comparable to having longer crankarms-more leverage can be applied to rear hub.

    Not to mention the bigass ring looks super-kool. I'm sold on big/big. Super-sized front chainrings 4 ever!
    Attached Images Attached Images
    Last edited by Sincitycycler; 12-19-07 at 10:17 PM.
    "How did all those 'Keep Off the Grass' signs get there?"

  2. #2
    Hello. crushkilldstroy's Avatar
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    Make sure you keep them there chainring bolts tight. A 60t chainring will fold easier than a 48t one will if you lose a bolt.
    Quote Originally Posted by Jacquie Phelan
    Until mountain biking came along, the bike scene was ruled by a small elite cadre of people who seemed allergic to enthusiasm.

  3. #3
    . blickblocks's Avatar
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    Pics?

    Bigger rings and cogs should make your chain last longer, no? When I build up my bolt-on cog wheel (maybe with a disc ENO) I want to use a large cog for this purpose.

  4. #4
    Al noisebeam's Avatar
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    2.)

  5. #5
    Senior Member Sincitycycler's Avatar
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    Quote Originally Posted by crushkilldstroy View Post
    Make sure you keep them there chainring bolts tight. A 60t chainring will fold easier than a 48t one will if you lose a bolt.
    Roger that.
    Good thing I'm not that strong like somebody who could push a 60x15...
    "How did all those 'Keep Off the Grass' signs get there?"

  6. #6
    bward1028
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    where'd you find a chainring that big?

  7. #7
    Senior Member Sincitycycler's Avatar
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    Quote Originally Posted by blickblocks View Post
    Pics?

    Bigger rings and cogs should make your chain last longer, no? When I build up my bolt-on cog wheel (maybe with a disc ENO) I want to use a large cog for this purpose.
    Can you recommend a free photoshop site so that I can reduce the file size for BF? Irfanview charges now...
    "How did all those 'Keep Off the Grass' signs get there?"

  8. #8
    jooseyo Tangsooyuk's Avatar
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    imageshack.us
    Quote Originally Posted by Tadashi View Post
    Multiple gears make you weak, period.

  9. #9
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    Quote Originally Posted by Sincitycycler View Post
    I'm sure it's due to the fact that the larger diameter rear cog of the 20t vs. the 16t is comparable to having longer crankarms-more leverage can be applied to rear hub.
    What? that might make a bit more sense if you kept the front ring the same, but you didn't. my guess would be placebo, or the fact that each part in the system was changed - so there could be minor things like the shape of the teeth that are giving a moderately different feel.

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  11. #11
    . blickblocks's Avatar
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    Quote Originally Posted by Sincitycycler View Post
    Can you recommend a free photoshop site so that I can reduce the file size for BF? Irfanview charges now...
    Most sites should give you a thumbnail to post on message boards. I really like allyoucanupload.com because it's so fast.

  12. #12
    Al noisebeam's Avatar
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    Quote Originally Posted by Sincitycycler View Post
    Irfanview charges now...
    4.10 is still free. What do you mean?


    Al

  13. #13
    Senior Member Sincitycycler's Avatar
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    Quote Originally Posted by zip22 View Post
    What? that might make a bit more sense if you kept the front ring the same, but you didn't. my guess would be placebo, or the fact that each part in the system was changed - so there could be minor things like the shape of the teeth that are giving a moderately different feel.
    Same gear inches 78.8 (go to sheldon brown's site for verification), But I can definitely feel the difference. The rear cog is bigger. Longer moment arm in physics. Like 180mm cranks vs 165mm.

    I like to add that my chainline is not ideal for a 120mm rear spacing at 48mm (42mm is ideal) even though my new config makes zero noise. My 10-speed full Dura-Ace road bike makes more sound!
    "How did all those 'Keep Off the Grass' signs get there?"

  14. #14
    Senior Member Sincitycycler's Avatar
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    Quote Originally Posted by bward1028 View Post
    where'd you find a chainring that big?

    http://cgi.ebay.com/Road-MTN-Bike-CH...QQcmdZViewItem

    This guy is good. Super fast shipment
    "How did all those 'Keep Off the Grass' signs get there?"

  15. #15
    hello roadfix's Avatar
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    I can understand the theory behind the longer moment arm in the larger cog creating more torque and tightening even tighter on the hub compared to smaller cogs but actually feeling the difference between two identical ratios is hard to believe.

  16. #16
    Senior Member Sincitycycler's Avatar
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    Quote Originally Posted by roadfix View Post
    I can understand the theory behind the longer moment arm in the larger cog creating more torque and tightening even tighter on the hub compared to smaller cogs but actually feeling the difference between two identical ratios is hard to believe.

    Try it. It's just so smooth it's unbelievable.
    - NO noise using a 1/8 chain.
    -Imagine using a Campy 10 speed chain...
    Just gotta make sure ya got the right BB. That "flywheel" gets pretty close to the chainstay!
    "How did all those 'Keep Off the Grass' signs get there?"

  17. #17
    bward1028
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    are the vuelta ones ramped?

  18. #18
    . blickblocks's Avatar
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    Quote Originally Posted by bward1028 View Post
    are the vuelta ones ramped?
    Look at the picture. No ramping or pins. However the teeth don't look track profile.

  19. #19
    Gone, but not forgotten Sheldon Brown's Avatar
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    Quote Originally Posted by Sincitycycler View Post
    Same gear inches 78.8 (go to sheldon brown's site for verification), But I can definitely feel the difference. The rear cog is bigger. Longer moment arm in physics. Like 180mm cranks vs 165mm.
    Nope. The longer "moment arm" (radius) is cancelled out by the longer one in back, if the ratios are the same. That's physics.

    Your 60 tooth chainring will create less tension on the chain, so there will be less frame and BB spindle flex, and perhaps that's what you're feeling.

    (Although there's less tension, the chain moves faster/farther, so the same amount of work is done.)

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  20. #20
    some new kind of kick Suttree's Avatar
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    SB has spoken. SB has a posse.

  21. #21
    Senior Member mihlbach's Avatar
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    This is all BS placebo effect caused by the feel of a smoother drive train, possibly caused by newer and/or better components. Assuming crank length and wheel diameter are unchanged, the only way to change your gear is to alter the gear ratio. Beyond that, the total number of teeth in the chainring and cog is irrelevant. If you make the cog and chainring bigger but keep the gear ratio the same, your gain in leverage in the cog is countered by the loss of leverage with the larger chainring. For example, if your gear ratio is 3/1, it does not matter if you are running 30/10, 48/16, 60/20, or 90/30...the wheel still spins three times for every spin of the crank...your gear is unchanged. Any difference you feel has nothing to do with increased leverage. Larger cogs do wear the chain less, however, because the chain spins faster, putting less tension on the chain. They might also feel smoother because of less chain tension. But changing the number of teeth without altering the ratio will not give you more power no matter how you attempt to rationalize it.

    Didn't see Sheldon's post..but yeah, same thing.
    Last edited by mihlbach; 12-19-07 at 06:37 PM.

  22. #22
    get strange wild style's Avatar
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    Please post pictures. Really curious to see how it looks!

    Also, are those Vuelta rings 3/32 or 1/8?

  23. #23
    Senior Member TimArchy's Avatar
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    I've heard from several racers that there is some (probably psychological) effect of using larger/smaller gears of the same ratio.
    From several independent sources I've been told that smaller chainring/cog combos give better acceleration from slow speeds. Larger combos make it easier to stay on top of a faster cadence.

    These are my thoughts, unless they've already been contradicted by SB's earlier post, then someone else told me this:
    The relative radii of the crank arm circle and the chainring can have some effect on the moment of the lever. And since a gearing change in the chainring requires a much larger change in raduis than the equivilent gearing change in the cog, a change in the radius of the chainring can make a difference that the equivilent change in the cog cannot eliminate. So a crank arm that is relatively much longer than the radius of the chainring would provide a larger mechanical advantage.

    Of course, we are talking about instances where velocity is changing. When velocity stays constant, there would be no difference between 30x10 and 99x33. And I'm not bringing friction into the equation either, which I probably should.
    Quote Originally Posted by Josh Frank
    I will derive power from their cries of despair. My crank a speedy dervish, spinning and spinning through the darkest night that anyone with the audacity to try and suck my wheel will ever see...

  24. #24
    out of shape
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    Quote Originally Posted by kaiju-velo View Post
    SB has spoken. SB has a posse.
    we need stickers.

  25. #25
    Senior Member Sincitycycler's Avatar
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    Quote Originally Posted by blickblocks View Post
    Look at the picture. No ramping or pins. However the teeth don't look track profile.
    3/32" road chainring. Awesome quality for the $$
    "How did all those 'Keep Off the Grass' signs get there?"

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