Cermic Oversize Pulley
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  1. #1
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    Cermic Oversize Pulley

    Is it worth it buying this kind of upgrade? I heard that it helps a lot on flat roads to be more efficient.

    Let me know your thoughts

  2. #2
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    We will need more information to proper evaluate your question. Please include your personal stats, bike stats, what world record your going for and how close to it are you on the last attempt.
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  3. #3
    tlg
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    Only YOU can determine 'worth'. No one knows your finances.

    I heard that it helps a lot on flat roads to be more efficient
    Is that what you heard? What is a 'lot'?

    (hint ...it's not a lot)



    If you think 1w is a 'lot' and 'worth' it... go for it. If putting out 250w, you'll go 0.03mph faster!
    Last edited by tlg; 4 Weeks Ago at 04:29 AM.
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  4. #4
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    I didn't think these sounded like a crazy idea...until I saw the prices on them. You're halfway to a good used bike, if you know what you're looking for. Jeez.

  5. #5
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    It's much more economical to just lose few pounds.

    Sent from my moto x4 using Tapatalk

  6. #6
    tlg
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    Quote Originally Posted by nova_rider View Post
    It's much more economical to just lose few pounds.
    True. If you lose 4 lbs, putting out 250w, you'll go.... 0.03mph faster. (The same as the pulley)

    And that's on a flat. Go up a 5% grade and you'll be 0.15mph faster by losing 4lbs!! (5x faster than the pulley)
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  7. #7
    'brifter' is f'ing stupid
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    Quote Originally Posted by GiantRider View Post
    Is it worth it buying this kind of upgrade? I heard that it helps a lot on flat roads to be more efficient.

    Let me know your thoughts
    You heard from who? Why only flat roads...do they stop working on hills?
    This post should obviously be in 'components/wrenching' as well.
    #promechaniclife

  8. #8
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    Quote Originally Posted by tlg View Post
    True. If you lose 4 lbs, putting out 250w, you'll go.... 0.03mph faster. (The same as the pulley)

    And that's on a flat. Go up a 5% grade and you'll be 0.15mph faster by losing 4lbs!! (5x faster than the pulley)
    Actualy, 4 lbs. (2 kg) is worth about 0.4 mph on a hill.

  9. #9
    tlg
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    Quote Originally Posted by Kerry Irons View Post
    Actualy, 4 lbs. (2 kg) is worth about 0.4 mph on a hill.
    On 'a hill'? What is 'a hill'? At what power?
    Show your math.

    You ain't gaining 0.4mph on a 5% slope.
    https://www.gribble.org/cycling/power_v_speed.html
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  10. #10
    JCU
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    test again

  11. #11
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    5% a hill? Come on over, I'll show you a HILL!
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  12. #12
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    If you buy that, your wallet will be a few pounds lighter anyway.

    scott s.

  13. #13
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    Quote Originally Posted by duriel View Post
    We will need more information to proper evaluate your question. Please include your personal stats, bike stats, what world record your going for and how close to it are you on the last attempt.
    ...who you are employed by,...

  14. #14
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    It might or might not be a good idea if you race Cat 2 ..(maybe).....Every little bit helps.
    If your opinion differs from mine, ..........Too bad.
    .
    How would you like it if Hitler killed you
    Dogbert.

    I>U

    Buying parts to hang on your bike is always easier than getting fit.

    If you feel wimpy and weak, get out and train more, ya wee lassie!

    If Jesus had a gun, he'd be alive today!

  15. #15
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    Quote Originally Posted by tlg View Post
    On 'a hill'? What is 'a hill'? At what power?
    Show your math.

    You ain't gaining 0.4mph on a 5% slope.
    https://www.gribble.org/cycling/power_v_speed.html
    Go to analyticcycling.com or do the math for yourself using

    watts = [Vg*W(.0053 + %G/100) + .0083(Va^3)]*2

    where Vg = ground speed (mph) W = weight of rider + bike (lbs)
    Va = air speed (mph) %G = percent grade of hill

  16. #16
    tlg
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    Quote Originally Posted by Kerry Irons View Post
    Go to analyticcycling.com or do the math for yourself using
    lol. Thanks! That confirms what I said!
    You ain't gaining 0.4mph on a 5% slope

    analyticcycling.com
    Speed For Given Power
    Speed For These Parameters 5.61 m/s (12.54921 mph)
    Power 250 watts
    Frontal Area 0.5 m2
    Coefficient Wind Drag 0.5 Dimensionless
    Air Density 1.226 kg/m3
    Weight Rider & Bike 75 kg
    Coefficient of Rolling 0.004 Dimensionless
    Slope of Hill 0.05 decimal

    Speed For Given Power
    Speed For These Parameters 5.51 m/s (12.32552 mph)
    Power 250 watts
    Frontal Area 0.5 m2
    Coefficient Wind Drag 0.5 Dimensionless
    Air Density 1.226 kg/m3
    Weight Rider & Bike 76.81 kg
    Coefficient of Rolling 0.004 Dimensionless
    Slope of Hill 0.05 decimal

    12.54921 mph - 12.32552 mph = 0.22 mph.


    According to your analyticcycling.com, 8lbs is worth 0.4mph. Not 2lbs.

    Speed For Given Power
    Speed For These Parameters 5.43 m/s (12.14656 mph)
    Power 250 watts
    Frontal Area 0.5 m2
    Coefficient Wind Drag 0.5 Dimensionless
    Air Density 1.226 kg/m3
    Weight Rider & Bike 78.4 kg
    Coefficient of Rolling 0.004 Dimensionless
    Slope of Hill 0.05 decimal

    12.54921 mph - 12.14656 mph = 0.40 mph.


    Feel free to do (and show) the work yourself.
    Custom Di2 & Garmin/GoPro mounts 2013 SuperSix EVO Hi-MOD Team * 2004 Klein Aura V

  17. #17
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    I like them, can afford them, notice what they do to drive train friction (at least in the workstand ), and don't care what anyone else thinks, so worth it to me. Only you can make the decision for you.
    Well, you know, that's just, like, your opinion man. - The Dude

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