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  1. #1
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    Bigger rotors necessary for bigger riders?

    So I'm using BB5's with 160mm rotors on my trail 29er, which appears to be what my Diamondback Overdrive frame would have come with stock, had I bought it as a whole bike. I know I'm not talking about high-end gear here, but I feel like the the V-brakes on my 26" commuter just do a way better job. I know disc brakes are notorious for being noisier than V-brakes, but mine seem to make awful awful noises on steep descents once they get hot, and the front doesn't seem to grab hard enough (yes they are adjusted properly. They seem to work fine on milder descents or street riding, where they don't get as hot).

    Should I think about switching up to a bigger front rotor? Will I need to go to a BB7 to utilize a bigger rotor? (I'd like to avoid the expense of going hydraulic, plus I like the way mechanical discs have similar lever-feel to V-brakes).

    Pic for reference:

    (I'm 5'10", 240lbs and dropping)

  2. #2
    What could go wrong ...
    Reputation: Zoke2's Avatar
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    all you will need is a 180/185 rotor and a 180/185 adapter for the caliper ... going to 180 in the the front was the best upgrade I have done in a long time
    I used to ride to Win ... Now I ride to Grin

    While my guitar gently weeps, my bike sits there mocking me

  3. #3
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    Effit, just go ahead to 200mm up front and 180mm rear. You can never have too much braking power IMO.
    You can do it with the BB5s. Just like the poster above says, adapter for the caliper and new rotor.

  4. #4
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    I went ahead and stepped it up a wee bit:

    Alligator 203mm w/ appropriate Avid caliper adapter

    I lock up the rear pretty easily still so I'll hold off on upgrading that end for now. Pads and rotor haven't mated yet after just one quick run down the hill so I'll hold off on a proper ride report until I've put a few miles on it.


  5. #5
    Rub it............
    Reputation: frdfandc's Avatar
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    Make sure that your fork is able to handle the 203mm rotor. Too much leverage can damage the fork under hard breaking - snapping off the mounts on the fork.

  6. #6
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    I emailed Surly (the fork is a Karate Monkey) and asked about max diameter before ordering the rotor. The guy that got back to me said they don't specify a maximum diameter, but he's about my size and runs a 185 with no problems, and he's probably a more aggressive rider than me (i'm definitely still sort of a wimp).

    He did recommend I switch to bolt-on skewers instead of QR's, though, which is something I had planned to do anyway for extra security when my bike is locked up on campus.

  7. #7
    official eMpTyBRain
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    The answer to your question is:

    YES
    ...and proud member of the anti-sock puppet desolation

  8. #8
    29 some of the time...
    Reputation: AL29er's Avatar
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    Necessary? No. Nicety? Yes. At 240+lb I do like my 7in and 8in rotors, but technically I don't need them. I can get by on 6in rotors fine, but they do fade, overheat, and require more finger pressure to slow down my girth.
    Quote Originally Posted by saturnine
    that's the stupidest idea this side of pinkbike.

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