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  1. #1
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    noob rotor size question

    I did a quick search but couldnt find an answer to my question. I have a 2005 Specialized Hardrock Sport Disc (XXL). Everything except the grips and saddle is stock. I bought the bike new but never really rode it. The wife and I finaly decided to go out riding and I love it. However, the brakes on it suck. I'm a big guy (6'-6" 290#) and when I grab a couple handfulls of brake levers, the brakes try their hardest, but cant stop me very quickly. I'm afraid to take the bike on an steep downslopes because I'm afraid I wont be able to stop quickly if I need to. I did some research on brakes and I decided to go with BB7's because of their low price and good reviews from others on this site. My question is in regards to the rotor size. How do I determine the largest rotor size I can fit on my bike? I feel that with my weight, I cant go too big! In the future I ill probably look into hydros more, but for now they are too expensive. Thanks in advance

  2. #2
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    Did you break in the rotors and pads correctly, doing a number of good hard stops. It takes a while but I find that with new rotors after about 5 hard stops I get good braking. They will keep getting better after that but good enough to ride.

    Maybe the rotors and/or pads got contaminated with something?

    As for rotor size...the front will fit anything but the rear will have clearance issues. You can only guess by looking at your current rotor frame clerance to figure how much bigger you can go. You probably have 6" rotors. You should be able to go 7". The 6" should stop you as good as the 7". You just have to squeeze the 6" harder. The larger rotors will stay cooler which is good.

  3. #3
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    A larger rotor up front will depend on the fork, some aren't even rated for larger than 160 (but some go bigger anyways, your risk). Rear isn't likely an issue but sometimes larger rotors simply won't fit (Special ed may put the max size info on their website). I'd think a 185 rotor up front would do the trick, but maybe a 203. What brakes are you replacing with the BB7s? What brake levers are you using? If you never really rode it there's also the possibility you never bedded in the pads and rotors in the first place?
    Last edited by Bikinfoolferlife; 06-03-2009 at 02:04 PM.
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  4. #4
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    I have put some miles on the bike with plenty of stops. I guess I worded my question poorly. I have heard that the stock brakes (Tektro IO mechanical disc, 6" rotor front and rear) leave alot to de desired by the lighter guys. The stock brake levers are Shimano Altus. As far as the front fork, this is what it says on Specialized's website: RST Gilla Plus T5, 100mm travel, preload adjust, 30mm Cr-Mo stanchion and 1-1/8� steerer, coil/MCU spring.
    I know the bike I have isnt the greatest, but its what I could afford at the time. I will upgrade it a little until I am certain that I will stick with biking, then I will be more willing to drop some cash on a serious bike.

  5. #5
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    The BB7 is the best mechanical disc brake, Tektro not so much.

    There are better brake levers than the Altus for a mechanical disc brake. The ones that offer a leverage adjustment like Avid's SpeedDial adjustment (some Shimano levers also have a similar adjustment, don't think the Altus do, but might depend on specific model of Altus).

    I'd guess the RST Gila T5 might not be rated for the larger rotors, but a quick google got me nothing one way or the other but I didn't look all that hard....

    PS You might try phoning Special ed for specifics on the fork/frame for max rotor recommendations...
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  6. #6
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    Quote Originally Posted by chowder_pants
    As far as the front fork, this is what it says on Specialized's website: RST Gilla Plus T5, 100mm travel, preload adjust, 30mm Cr-Mo stanchion and 1-1/8� steerer, coil/MCU spring.
    Given those specs, I'd stick with 6" rotors front and rear.

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