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  1. #1
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    dumb crank length question

    I have a Kilo TT, it is a 50cm. I can deal with the toe overlap but I hate my truvativ cranks. If I use a spare set of cranks I have which which are 170s will the toeverlap be 5 mm or more/less than the 165s I run currently?

    Will I crash in a ball of flame? Not even notice it?

    thanks

  2. #2
    jerk store mathletics's Avatar
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    Not notice. More likely you'd notice pedal strike than toe overlap, but even then, think about it. 5mm is half a centimeter, which is less than half an inch. Especially considering that 165 and 170 are both commonly used sizes, it should be no problem.

  3. #3
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    Man, on a barely related note, I looked at my cranks to see what length they were (they're stock '71 Peugeot cranks still and I want something shorter).

    171....wtf...

  4. #4
    cab horn
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    Quote Originally Posted by mathletics View Post
    Not notice. More likely you'd notice pedal strike than toe overlap
    No you won't. They are both equally negligible. I run 175's and i'm only 5'10 on my fixed gear. Learn your limits, know your bike. Don't be a ****tard.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

  5. #5
    Senior Member mihlbach's Avatar
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    Why do you hate the truvativ cranks? Too flexy...Q-factor too wide, or some aesthetic reason. If its the later, I wouldn't bother changing cranks. You may notice the difference. For instance, on my track bike with clipless pedals, I get noticeable toe-tire rub with 170mm cranks, but no shoe tire contact with 167.5 mm cranks. Stick with the shorter cranks...they will minimize toe-overlap, pedal strike, and increase your cadence window.

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    Quote Originally Posted by mihlbach View Post
    Why do you hate the truvativ cranks? Too flexy...Q-factor too wide, or some aesthetic reason. If its the later, I wouldn't bother changing cranks. You may notice the difference. For instance, on my track bike with clipless pedals, I get noticeable toe-tire rub with 170mm cranks, but no shoe tire contact with 167.5 mm cranks. Stick with the shorter cranks...they will minimize toe-overlap, pedal strike, and increase your cadence window.
    They are noisy (they whir? I tightened /lube everything it never goes away) and I think they are limited in bottom bracket choices. the ugliness I can deal with. My toe overlap is pretty severe anyway, Ideally I would replace them with another set of 165s but I have these 170s sitting here...

  7. #7
    cab horn
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    Quote Originally Posted by scrub View Post
    They are noisy (they whir? I tightened /lube everything it never goes away) .
    Time to get 3/32. I run a $20 MEC ring up front and a $15 iro cog with a sram pc48. Dead ****ing silent.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

  8. #8
    Senior Member mihlbach's Avatar
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    Quote Originally Posted by scrub View Post
    They are noisy (they whir? I tightened /lube everything it never goes away)
    HMM...sounds like it could be a problem with your chainring, chain, or both (chainline?).
    What kind of cranks are you going to replace them with?

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    Quote Originally Posted by mihlbach View Post
    HMM...sounds like it could be a problem with your chainring, chain, or both (chainline?).
    What kind of cranks are you going to replace them with?
    I run a rocket ring, so maybe I'll replace that first, its not very round. I had thought of chainline but I measured it and it seems w/in a mm. I have a set of 170 square taper that I'd use.

  10. #10
    Senior Member mihlbach's Avatar
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    Quote Originally Posted by scrub View Post
    I run a rocket ring, so maybe I'll replace that first, its not very round. I had thought of chainline but I measured it and it seems w/in a mm. I have a set of 170 square taper that I'd use.
    I have a rocket ring on my beater rain fixie, bolted to an old pair of Shimano 105 cranks, with a KMC 510HX chain that is very round and spins very smoothly. I've heard that rocket rings aren't made to the highest tolerances, so I guess I got lucky.

  11. #11
    Ths Hipstr Kills Masheenz cc700's Avatar
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    i put 170's on my 53cm kilo tt from the buildup...

    it's fine. you have to think about it and it will be worse when you get out the tape measure and compass, but i doubt you'd notice it while riding.

  12. #12
    Boston did not sob 9Rings's Avatar
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    Longer cranks give you more leverage, and thus more power per revolution. I think the determining factor is your height, as to whether longer cranks would be the way to go (assuming you don't go too far, pedal strike, etc...)
    Mongol General: "What is best in life?"
    Conan: "To crush your enemies, to see them driven before you, and to hear the lamentations of their women."

  13. #13
    aka CS NoBumDeals's Avatar
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    What the the relation of height-to-crank-length?

  14. #14
    Senior Member frymaster's Avatar
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    Quote Originally Posted by scrub View Post
    <snip> If I use a spare set of cranks I have which which are 170s will <snip> I crash in a ball of flame? Not even notice it?
    when i was a wee lad i read this interview with greg lemond in which he attributed his time trial success in part to knowing when and how to pedal through corners. so i went out and practiced with my standard 170s and found (the hard way) that it takes a really steep turn to dig a pedal. ouch-ed my shoulder up nicely and slid the bike into a shrub (took some doing to get it out) but i haven't had a pedal strike in the twenty years since.

    the bottom line is, if you know the limits of how step you can turn you won't have a problem.

  15. #15
    Boston did not sob 9Rings's Avatar
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    Quote Originally Posted by NoBumDeals View Post
    What the the relation of height-to-crank-length?

    http://www.billbostoncycles.com/crank_length.htm

    This one is more for determining what size for you (18.5% of femur length)
    http://www.peterwhitecycles.com/fitting.htm

    And this one talks about power output related to crank length:
    http://www.analyticcycling.com/Pedal...ngth_Page.html
    Mongol General: "What is best in life?"
    Conan: "To crush your enemies, to see them driven before you, and to hear the lamentations of their women."

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