Results 1 to 8 of 8
  1. #1
    mtbr member
    Reputation: hrsjqb1's Avatar
    Join Date
    Apr 2004
    Posts
    119

    Larger rotors for mechanical disc brakes

    Do larger rotors provide more stopping power for mechanical disc brakes? Is it worth the upgrade? Say 160 - 203mm.

    Thanks.

  2. #2
    56-year-old teenager
    Reputation:
    Join Date
    Aug 2006
    Posts
    1,763
    Yes, larger rotors will provide more stopping power. But for XC use for all but the biggest Clydes, a 160 mm should be adequate.

    What kind of riding do you do, how much do you weigh, and what isn't working for you?

  3. #3
    Nouveau Retrogrouch SuperModerator
    Reputation: shiggy's Avatar
    Join Date
    Dec 1998
    Posts
    47,994
    I am an 170lb XC/Trail rider and use 185/160 rotors with my Avids. Like the extra power, reduced finger effort and lack of fade on long descents.
    mtbtires.com
    The trouble with common sense is it is no longer common

  4. #4
    local trails rider
    Reputation: perttime's Avatar
    Join Date
    Aug 2005
    Posts
    11,825
    Frame and fork manufacturers may tell you to keep the rotor size down. A bigger disk with more braking power can put more strain on the fork or rear stays.

    Just something to check...

  5. #5
    On MTBR hiatus :(
    Reputation: Speedub.Nate's Avatar
    Join Date
    Dec 2003
    Posts
    9,145
    160 swpped out for 185 on my Avid mechs made a big improvement in my braking.

    I made the switch back in the days when I had an extra 30+ pounds hanging off of me, not because the smaller rotors lacked power, but because they constantly overheated on prolonged downhills.

    The change to 185 did bring some extra power (little grabbier in the slow, rocky/rutty stuff), but they also increased the amount of rotor material by approximately 50%, making a much better conduit to get heat away from the brake track. So the more appreciated change was no more sing-along, rainbow-discolored rotors!
    speedub.nate
    · MTBR Hiatus UFN ·

  6. #6
    mtbr member
    Reputation: hrsjqb1's Avatar
    Join Date
    Apr 2004
    Posts
    119

    Thanks all...

    It sounds like more rotor helps on mechanical disc brakes as much as it does on hydraulic. Do mechanical disc brakes fade when overheated, I am unsure since there is no fluid to heat? I am considering this modification as a bit of a gift to a buddy I will be ridding with at Silverton Mountain next weekend that has a set of BB5’s on his Cannnondale Prophet. We ride a mix of trail and Freeride type stuff and because Silverton is so steep I worried that his 160mm rotors would become as Speedhub put it “rainbow discolored” and either warp or loose some or all stopping power. He is a reasonably light rider but we do get into the steep stuff pretty regularly Silverton Mountain as mentioned above is really steep (and fun, go if you have a chance during their tragically short season), Keystone, Vail, Pajarito, and perhaps Snowshoe this year.

  7. #7
    On MTBR hiatus :(
    Reputation: Speedub.Nate's Avatar
    Join Date
    Dec 2003
    Posts
    9,145
    Quote Originally Posted by hrsjqb1
    ...I worried that his 160mm rotors would become as Speedhub put it “rainbow discolored” and either warp or loose some or all stopping power. He is a reasonably light rider but we do get into the steep stuff pretty regularly
    Please, enough with the formalities... call me Nate.

    I'd wouldn't stress it. If he is light, have him ride Silverton and see how the brakes hold up. Likely he won't overheat or require more power. If he does, then you know the drill.

    If you do up to 185's, order up a whole BB7 kit (they're relatively cheap on eBay), and get rid of that front BB5 caliper.

    I don't know the particulars of brake fade on mechanical discs. When mine overheated, there was a slight loss of braking power, but nothing crazy. The biggest annoyance was the constant squeeling, which kept me light on my front brake just for some peace and quiet.
    speedub.nate
    · MTBR Hiatus UFN ·

  8. #8
    mtbr member
    Reputation:
    Join Date
    Dec 2003
    Posts
    3,335
    There are two type of heat induced brake fade. The first and most common is overheating the pads which results in outgassing. When then happens you still have a firm lever, but the brakes simply lose their effectiveness. This will happen regardless of if the caliper is mechanical or hydro.

    The second kind of fade occurs when you boil the fluid. This can only happen with hydro brakes. When this occurs the lever will get very soft and mushy and often go all the way to the bar. This is very rare and would usually indicate the fluid is contaminated.
    Riding slowly since 1977.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •