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  1. #1
    ah...oh yeah..i forgot
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    Help me determine the correct rotor size...anyone???

    I got my new black fork, and put the avid mechanical fork on it. I'm still a bit concerned with the lack of clearance between the inner adjusting knob and the spokes. If I were to get this adapter, it says I would need a larger rotor to compensate. My question is how large of a rotor would I need? I currently have the stock 160mm. My reasoning for wanting this adapter is that it will move the caliper out from the center of the hub and give a little more clearance between the spokes and the adjusting knob. That's my hope anyway.
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    Last edited by mikeyjunior; 02-06-2004 at 08:18 AM.

  2. #2
    Spring! Spring! Spring!
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    I'd advise getting the Avid 185mm rotor and adapter.

    Warning: >160mm rotors will void warranty on some forks.

    More brake power == good IMHO.

    Good luck,
    -t

  3. #3
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    Don't bother with that adapter...

    In the end, the caliper has to be set according to the position of the rotor. The rotor position isn't going to change much relative to the spokes by switching to a 170mm rotor. (The spokes angle away from the caliper but you'll maybe gain 1mm clearance for each 20mm of rotor diameter increase).

    In fact, it isn't going to change much going to a 185mm rotor, although that should give you a little more comfort factor.

    My best advice is to shim out the rotor from the hub just a tiny amount (if clearance is really a problem). The Avid CPS system allows the caliper to follow suit, and this will get the increased clearance you desire.

    If you decide to go to a bigger rotor, forget about that POS adapter you're considering. Just get an Avid 185mm kit and Avid's Manitou adapter. But don't forget that a larger rotor will decrease slow speed braking feel and make brake application much more grabby, so if you're a lighter guy and/or do a lot of rock crawling, think twice about it.

  4. #4
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    Call up Avid (phone number on their website) and tell them that you need the Post Mount adapter for a Manitou fork. I have a skareb comp with avid 185mm rotors and didn't have to change the size of the rotor with the new mount.

  5. #5
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    Frankly, IMHO fnaetik is THE Avid expert...

    ...but I will say that I switched to a 208mm front rotor and don't regret it one bit. It is stronger, and at first it seemed grabbier and to have less feel as fnaektik pointed out. However, I adjusted pretty quickly, and it is no longer an issue in any way. Even better, it is now a one or two finger brake for me. Even after VERY long descents, my hand doesn't get sore anymore. That alone was worth the switch. Based on my experience with the 208mm, I can't imagine that the 185mm rotor will be tough for you to adjust to in any way.

    Having said all of that, I'm 200 pounds, my bike is 34 pounds, and maybe that's the ticket for a 208mm rotor. If you are 145 pounds with a 25 pound bike, maybe the 160mm or 185mm is ideal for you.




    , despite that fact that I often ride
    Quote Originally Posted by f*nŠtik
    In the end, the caliper has to be set according to the position of the rotor. The rotor position isn't going to change much relative to the spokes by switching to a 170mm rotor. (The spokes angle away from the caliper but you'll maybe gain 1mm clearance for each 20mm of rotor diameter increase).

    In fact, it isn't going to change much going to a 185mm rotor, although that should give you a little more comfort factor.

    My best advice is to shim out the rotor from the hub just a tiny amount (if clearance is really a problem). The Avid CPS system allows the caliper to follow suit, and this will get the increased clearance you desire.

    If you decide to go to a bigger rotor, forget about that POS adapter you're considering. Just get an Avid 185mm kit and Avid's Manitou adapter. But don't forget that a larger rotor will decrease slow speed braking feel and make brake application much more grabby, so if you're a lighter guy and/or do a lot of rock crawling, think twice about it.
    I'll be along... eventually.

  6. #6
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    No post mount adapter is needed...

    Quote Originally Posted by BrandonAggsMntnBk
    Call up Avid (phone number on their website) and tell them that you need the Post Mount adapter for a Manitou fork. I have a skareb comp with avid 185mm rotors and didn't have to change the size of the rotor with the new mount.
    ...unless he chooses a larger rotor size. With the stock 160mm rotor that he has, the Avid caliper bolts directly to the fork.

    With the 185mm, you're correct, then the Avid adapter is necessary.

    The 185 rotor and adapter are also available through the usual suspects: aebike, hammerheadbikes, speedgoat, etc.

  7. #7
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    Quote Originally Posted by msylvan

    Having said all of that, I'm 200 pounds, my bike is 34 pounds, and maybe that's the ticket for a 208mm rotor. If you are 145 pounds with a 25 pound bike, maybe the 160mm or 185mm is ideal for you.
    I think that's the key. I switched to 185's on the front of my bikes and frankly, with my weight and terrain I ride, I was overheating the stock 6" rotors and had to make the change. They actually were powerful enough up until they began to run hot.

    But even at my current 200 pounds, when I get into slow, technical terrain, I want my 6" rotors back. It's not something I don't overcome, but having made the comparison it's difficult for me to not acknowledge the difference. It definitely pays to evaluate front rotor size based on weight and terrain.

  8. #8
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    Rotor size for my size...

    This thread has been helpful for determining rotor size. But, what would you guys think is the best size for me? I'm 5'4" @ 115 lbs. Yes, yes, small guy. I'm looking into getting the Avid mechanical disc brake at Price Point and they have three options; 160, 185, and 203mm. Which would be the best? Also, should the front and back be different sizes? Thanks

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