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Braking force and rotor sizes

bennett_346bennett_346 Posts: 5,092
edited June 2010 in MTB beginners
Out of interest, how much difference in power would a 185 rotor have compared with a 160? Specifically Juicy 3s?
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Posts

  • supersonicsupersonic Posts: 82,708 Lives Here
    The percentage difference in diameter.

    It menas you will have to put less force in the lever for a given braking 'power'.
  • bennett_346bennett_346 Posts: 5,092
    supersonic wrote:
    The percentage difference in diameter.
    Thats handy to know, so 13.5%.
  • AnonymousAnonymous Posts: 79,692
    15.6%, even.
  • Chunkers1980Chunkers1980 Posts: 8,035
    or odd

    15.625...
  • bennett_346bennett_346 Posts: 5,092
    15.6%, even.
    ?

    I checked my calculations, and got 13.5%.

    100 - ((160/185)x100) = 13.515%
  • Chunkers1980Chunkers1980 Posts: 8,035
    It's a percentage of the original - nowt to do with the bigger size apart from the difference.

    160 * 115.625
  • AnonymousAnonymous Posts: 79,692
    erm, what?
    185/160=1.15625

    Which means that 185 is 1.15625 times bigger than 160, which means it's 15.6(25)% bigger, simplez.
  • bennett_346bennett_346 Posts: 5,092
    It's a percentage of the original - nowt to do with the bigger size apart from the difference.

    160 * 115.625
    You've lost me. I took a percentage difference between 185 and 160, which supersonic said to do. Unless i've just rewritten basic maths somehow, which i likely.
  • AnonymousAnonymous Posts: 79,692
    or odd

    15.625...
    :lol:
  • AnonymousAnonymous Posts: 79,692
    It's a percentage of the original - nowt to do with the bigger size apart from the difference.

    160 * 115.625
    You've lost me. I took a percentage difference between 185 and 160, which supersonic said to do. Unless i've just rewritten basic maths somehow, which i likely.
    Happens all the time on this forum - which is why any physics based debates go on forever and ever, and people still buy things for the wrong reasons.
  • bennett_346bennett_346 Posts: 5,092
    It's a percentage of the original - nowt to do with the bigger size apart from the difference.

    160 * 115.625
    You've lost me. I took a percentage difference between 185 and 160, which supersonic said to do. Unless i've just rewritten basic maths somehow, which i likely.
    Happens all the time on this forum - which is why any physics based debates go on forever and ever, and people still buy things for the wrong reasons.
    Hmm, since theres barely any noticeable difference ill just agree with your response, although not being too mathmatically minded i dont see how either method differs xD
  • Chunkers1980Chunkers1980 Posts: 8,035
    BODMAS...
  • bennett_346bennett_346 Posts: 5,092
    BODMAS...
    I understand bodmas, i just didnt do the right method.
  • bennett_346bennett_346 Posts: 5,092
    Which begs the question, what the hell did i just calculate o_0
  • Chunkers1980Chunkers1980 Posts: 8,035
    160 1.15625 185 18160 0.864864865 0.135135135
  • bennett_346bennett_346 Posts: 5,092
    Ahhh i see exactly what 've done, stupid me. Gahh, its been a long day, got up early to cycle to college and got some dog censored on my tyres on the way down, which got on my back, then arrived to find lessons had suddenly been cancelled without notice.

    Excuses excuses hehe
  • 160 1.15625 185 18160 0.864864865 0.135135135

    thats a long IP address... you're not fooling anyone!
  • AnonymousAnonymous Posts: 79,692
    bigbenj_08 wrote:
    160 1.15625 185 18160 0.864864865 0.135135135

    thats a long IP address... you're not fooling anyone!
    :lol: Must be IPv6
    ah, there's no place like 127.0.0.1 :oops:
  • biff55biff55 Posts: 1,404
    and the highest prime no. is ?
    he-he , that'll keep the maths guru's busy for a while.
    :twisted:
  • AnonymousAnonymous Posts: 79,692
    biff55 wrote:
    and the highest prime no. is ?
    he-he , that'll keep the maths guru's busy for a while.
    :twisted:
    Hasn't been found yet, has it.
  • Father FaffFather Faff Posts: 1,176
    Bloody hell, what is so difficult about (185-160)/160. This is like kindergarten maths isn't it?
    Commencal Meta 5.5.1
    Scott CR1
  • biff55biff55 Posts: 1,404
    biff55 wrote:
    and the highest prime no. is ?
    he-he , that'll keep the maths guru's busy for a while.
    :twisted:
    Hasn't been found yet, has it.

    they best crack on then.
    :wink:
  • M1llh0useM1llh0use Posts: 863
    biff55 wrote:
    and the highest prime no. is ?

    an odd number.

    :wink:
    {insert smartarse comment here}
  • QuirrelQuirrel Posts: 235
    Interesting that they haven't gone for rim disk brakes like Buell yet Buell_disk_brake.jpg
  • biff55biff55 Posts: 1,404
    M1llh0use wrote:
    biff55 wrote:
    and the highest prime no. is ?

    an odd number.

    :wink:

    which one ?
    :wink:
  • AnonymousAnonymous Posts: 79,692
    Quirrel wrote:
    Interesting that they haven't gone for rim disk brakes like Buell yet
    Only Buell though, isn't it?
    I'd imagine if it offered a genuine advantage, that MotoGP bikes would all be using them.
  • QuirrelQuirrel Posts: 235
    Quirrel wrote:
    Interesting that they haven't gone for rim disk brakes like Buell yet
    Only Buell though, isn't it?
    I'd imagine if it offered a genuine advantage, that MotoGP bikes would all be using them.

    As far as I know it's only Buell, but they were always a bit strange. Yet they are really strong brakes. Worked as well as any twin disc design I rode.

    Next question is why do none of the DH bikes run twin discs yet?
  • AnonymousAnonymous Posts: 79,692
    Quirrel wrote:
    Quirrel wrote:
    Interesting that they haven't gone for rim disk brakes like Buell yet
    Only Buell though, isn't it?
    I'd imagine if it offered a genuine advantage, that MotoGP bikes would all be using them.

    As far as I know it's only Buell, but they were always a bit strange. Yet they are really strong brakes. Worked as well as any twin disc design I rode.

    Next question is why do none of the DH bikes run twin discs yet?
    Because they're not needed. People are already complaining that the newer 4 pot saints were far too powerfull.
    Twin discs would add more power, less modulation, and more weight.
  • QuirrelQuirrel Posts: 235
    I suppose there is quite a difference between stopping 220kg + rider from190mph and stopping 100kg all inclusive.
  • zedheadzedhead Posts: 101
    People are already complaining that the newer 4 pot saints were far too powerfull.

    So if the calipers are powerful enough, why have a larger disc and therefore increased weight?
    Or do (fast) downhill bikes need to have big discs for cooling purposes?
    Felt Z85, Scott Thicko, modified Giant full suss (both nicked)- beat-up single-speed rigid 1992 Saracen, and various 2-wheelers with big engines
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