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  1. #1
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    Rear rotor size question...

    I'm about to purchase some new Avid Bb7's for my Azonic Steelhead and I'm wanting to know if there is a size limit to the rear rotor? Will I be able to put a 185mm on or should I stick with a smaller 165mm? Any help here is appreciated. Thanks!
    Azonic Steelhead XL
    Azonic Outlaw wheels
    Kona Cranks
    BB7's with 185mm disc
    Maxxis Holy Rollers
    Marz Z3

  2. #2
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    all you need is the proper adapter and you should be good to go

  3. #3
    Meh.
    Reputation: XSL_WiLL's Avatar
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    It depends on the frame. The stays may not offer adequate clearance for a larger rotor.

    What do you plan to use the bike for? Anything short of DH... stick to the 160mm rotor. It's lighter, more out of the way, etc.

  4. #4
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    stick with 6" rotor
    no need for something larger on the rear brake...
    the wheel will lock up even with 6"...

  5. #5
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    I was just considering the 185mm because I found a good deal on it. Thanks for the info though.
    Azonic Steelhead XL
    Azonic Outlaw wheels
    Kona Cranks
    BB7's with 185mm disc
    Maxxis Holy Rollers
    Marz Z3

  6. #6
    wyrd bi ful rd
    Reputation: chinaman's Avatar
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    185mm more than sufficient for the rear ... dont think you need any more ... make sure you get the right adaptor for it
    Last edited by chinaman; 01-03-2008 at 12:53 PM.

  7. #7
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    Quote Originally Posted by nj82tj
    I'm about to purchase some new Avid Bb7's for my Azonic Steelhead and I'm wanting to know if there is a size limit to the rear rotor? Will I be able to put a 185mm on or should I stick with a smaller 165mm? Any help here is appreciated. Thanks!
    As for IF the 185 will fit, you may have to write the manuf. for that. Richard Cunningham of Mt. Bike Action magazine wrote not too long ago that for most riders, 6" or 10" rotors in the rear does not matter. Once it locks, it locks. I just swapped my 185mm for 160mm rear for my BB7s last night. But I do have 185mm in the front...so if you're getting a great deal, go for it!

  8. #8
    J'aime le Dunkeld
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    Quote Originally Posted by onegymrat
    Richard Cunningham of Mt. Bike Action magazine wrote not too long ago that for most riders, 6" or 10" rotors in the rear does not matter.
    He can say that all he wants, but it won't stop a 6" rotor overheating.

  9. #9
    Flaccid Member
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    Quote Originally Posted by kenneththecurtain
    He can say that all he wants, but it won't stop a 6" rotor overheating.
    Or a 180mm rotor, if you are a Clyde. Weight, like in 240 pounds, puts a strain on all braking systems except the largest of rotors.

  10. #10
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    Well, I emailed Azonic and they responded with a "yes, there should be no issues, but let us know if there are." So, I'm thinking I should be alright. And secondly, I guess I'm happy now going with a 185 since I am a bigger guy. 6'2" 250ish isn't to easy on breaks.
    Azonic Steelhead XL
    Azonic Outlaw wheels
    Kona Cranks
    BB7's with 185mm disc
    Maxxis Holy Rollers
    Marz Z3

  11. #11
    Spring! Spring! Spring!
    Reputation: bear's Avatar
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    larger rotors give more surface for heat dissipation, which results in both more power and more modulation, in my opinion.

    but in general you'd have to be massing a lot more than 250# to truly need a 7" or larger rotor on the back - or you'd need to regularly be doing a lot of long DH where you need to dissipate the heat.

    i roll a 6" normally, but when I head out of Texas to somewhere with long downhills I switch to 7" 'cause it makes me happier (and I lost the ability to boil water on the hub shell).

  12. #12
    willtsmith_nwi
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    Quote Originally Posted by bear
    larger rotors give more surface for heat dissipation, which results in both more power and more modulation, in my opinion.
    No, it just takes longer for your fluid to boil and pads to melt.

    OP, unless you are riding downhill you don't need anything larger than a 160mm on the back. In fact, many XC riders on 26" wheels are going to 140mm rotors on the back.

    Whenever you brake you transfer weight to the front wheel. Whenever you go downhill you transfer your weight to the front wheel. Basically, in all serious braking situations, the rear wheel looses it's loading. This reduces the force of friction accordingly and makes it VERY easy to lock up the rear wheel. Once it's locked ... it doesn't do you any good (hence anti-lock brakes in cars).

    There are lots of good deals out there to be had and brakes with 160mm rotors. Check Pricepoint.com. For XC duty, 185mm on the rear is over-overkill.

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