2005 Mono m4 #8 caliper rotor size and piston question- Mtbr.com
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  1. #1
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    2005 Mono m4 #8 caliper rotor size and piston question

    Just picked up a fleabay Mono m4 caliper that looks to be an 05 from the alloy pistons.

    Two questions:

    1. The caliper is a number 8. The rotor I need appears to be in the 200mm range. What rotor size is this exactly spaced for? I note Hope has some 200's available, but I don't know where the crossover was.

    2. They changed to composite pistons for better heat rejection in 2006. Will the alloy piston calipers still hold up well to heat? This will go on the gf's bike and she's fairly light, although we're going to be doing mountain runs.

  2. #2
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    Hey JC,

    Number 8 caliper will give you 200mm on the front and, just for the record, 180mm on the rear. My partner is currently using one of my old Mono M4's with the alloy pistons on the front of her Stumpy (with a 180mm standard rotor) and hasn't experienced any overheating issues with the brake. I ran the same caliper with a 160mm floating rotor on the rear of my Big Hit, also without issue, although I would consider myself to be pretty economical with my braking.

    What use is a philosopher who doesn't hurt anybody's feelings? -
    Diogenes


  3. #3
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    Thanks a bunch. Lucky I looked you up before I bought a 203 rotor. Now to try and find one that won't cost a ton of $$$

  4. #4
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    There's a 180/200 pair on ebay UK (link) or a 200 floating rotor (the seller has two for auction) (link). The second one doesn't state international shipping, 'though there's no harm in asking.

  5. #5
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    FWIW, the Shimano 6 bolt 8 inchers are the same size if you can't score some cheap rotors. I run Mono4's and XT 4 pots on both bikes and can change out the wheels w/o any issues.

  6. #6
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    Actually Shimano 8 inch rotors are 203mm. That equates to 1.5mm difference on each side, so it may clear the caliper. But the pads aren't grabbing the right places.

    I've got the XT 4 pots too, the adapter even says 203 rotor only.

  7. #7
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    I've matched them up side by side and my Hopes that state 200mm and the Shimano ones that show 203 are exactly the same. I've never measured them, but either the Shimano is wrong or the Hopes are incorrect because they are identical.

    In any case, they both run fine on my bikes w/o any irregular wear on the pads or the rotors so IDK...no issues on my end.

  8. #8
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    I've got the same brakes you speak of JC. The front uses a 203. I just had to order a replacement from hope ~month ago. Seems like the rotor(floating) was about $55.00. I can't say i've had any significant heat issues. I've had the brakes since they were new, and have ridden a wide variety if trails with no problems (including some extended downhill).

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