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  1. #1
    mtbr member
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    Apr 2007
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    New question here. Large disc rotor on Lefty = Lefty broken?

    I have recently purchased a Caffeine 29er and am very happy with the bike.
    Today I went to my local Cannondale shop looking for an upgrade of my Avid BB5 brake with 6' rotors. I was interested in more powerful hydro brakes like Avid Code or something similar with 7' or 8' rotor in the front. I know they may be an overkill but I weigh 255 lbs and have felt that my current brakes and rotors are too "small" for me.
    But the sales person said that I should not mount 8' (not even 7') rotor in the front since my Lefty (Lefty Speed Bonded DLR2) is not designed for that and will likely break! He then showed the mounts for the caliper on a Lefty and said that they would not hold.
    Is this really official Cannondale recommendations - I find it very hard to believe?!
    This is an official Cannondale Japan store stating this (They only sell Cannondale).
    I have seen lots of Leftys with large rotors in this forum so I was very surprised to hear him say that.
    I live in Tokyo and my japanese language abilities are limited so I could not really discuss it with him.
    Having spent almost 2000 USD on the bike (Japan retail price) I would be very disappointed with the purchase if this is in fact true.
    Anybody having any info on the subject?

    Thanks!

  2. #2
    All Lefty's, all the time Moderator
    Reputation: MendonCycleSmith's Avatar
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    Quote Originally Posted by combatjojje
    Is this really official Cannondale recommendations - I find it very hard to believe?!
    As you said, many here are running them, and I've not heard of anyone, anywhere with a problem. I run a few, but on Max series forks. Teh difference is all on top, so I don't see a problem for you. If it concerns you, run a 7 instead of an 8. A more powerful set of brakes might make a 6 feel better too, if they are going to do the work, and won't get you what you want.
    This is a Pugs not some carbon wannabee pretzel wagon!!

    - FrostyStruthers



    www.mendoncyclesmith.com

  3. #3
    Rim Crusher
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    Doesn't make sense...............

    The larger brake rotor does not generate more stopping force, you just get better modulation control and more surface area for heat dissapation. The amount of force transferred to the caliper bracket does not change because the torque created during braking is unchanged. The maximum torque that can be generated is a function of the tire contact patch, rubber compound and the riding surface (coefficinet of friction). The amount of force required to overcome the force of gravity when you do a stoppie on pavement is the same regardless of how large the brake rotor is.

    At least that's how I see it!

    Big Brained Engineer types chime in here.........

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