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  1. #1
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    Rotor sizes; too big?

    A friend of mine isn't happy with standard rotor sizes, for his particular situation. He thinks he needs to go as big as possible, more or less. Why he thinks that, I'm not quite sure. Rather than running the standard 180 front/160 back, he insists that he must have 203 front/180 rear. For reference, he weighs about 165ish pounds, and rides both XC-oriented FS 29er and FS 26er. His riding is on mild to moderate trails only; never any jumping, thrashing, or harsh/dedicated DH riding, etc. I've tried to tell him that the 203/180 will be way too overkill for him, but he won't listen; he's too stubborn, and too set in ways. What do you think? Is he really on to something significant here, or am I right in trying to help point him in the better direction (e.g., just sticking with the standard 180/160 combo, given his weight and riding style)?

  2. #2
    human dehumidifier
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    I think it's no big deal to have too much brake, but a problem when you have too little. Also, there is no such thing as overkill when it comes to a bike, only limits on what a person can afford.
    I may or may not be laughing at you.

  3. #3
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    How about this, if he finds 203 front and 180 rear too powerful, switch the 180 up front and 203 back. 203 rear is good for those wet days where using too much front brake just leads to nasty wash outs

  4. #4
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    I wouldn't see the need myself. Check if the fork will accept a 203 first though. Not all forks are designed for that. Does he find himself overshooting corners? Maybe better pads is what he needs. If for example he's running resin pads a change to full metal will give more bite. I do think there is merit to a stronger front caliper. I think nearly all motorized vehicles have both larger front rotors and stronger front calipers than on the rear.

  5. #5
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    In all likelyhood he is using some pretty shitty braking technques...

    and his riding skills are not that great...

    On the other hand so what if he wants a 203mm rotor.....

    I run a 203/160 I got there becasuse I kept cooking brakes on long down hills I weigh about 185 lbs.

  6. #6
    Plays with tools
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    As long as he is within the manufacturer's recommendation or maximum rotor size let him do what he wants.

  7. #7
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    It's really just preference. As someone pointed out, if he does not like it, it won't cost him anything to go down to 180/160.

    Personally, I found that too big a rotor was a little bit of a drawback slower and lose conditions. Others can't get one big enough.

    What kind of brakes? If they are crappy ones, he may want to bigger ones just to make up for it.
    15mm is a second-best solution to a problem that was already solved.

  8. #8
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    1. He isn't trying to have the biggest rotors possible. That would be 203/203
    2. You might want to point out the downsides of big rotors such as:
    - More weight
    - slight bends or warping are more likely to cause rubbing
    - possible modulation problems
    - possible higher stress on the brake adapter and bolts (hence the reason for rotor size limits by some manufacturers).

    3. On the other hand, a bigger rotor gives you more power with less hand force, and stays cooler. So, it really comes down to a personal preference after looking at the pro's and cons.

    4. I've bombed down plenty of long steep Colorado downhills using 160's, or 180/160, and I weigh 190, so it is important to note that your friend does not have the "need" for these large rotors, but then again, a lot of our bike choices are based on personal likes and not on need.

  9. #9
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    I run 203 out front and out back, could not be happier. Went large cause on many of the rides I have long steepish down hills with you don't really want to overshoot the corner. Also at the time I was 225.

    ALso this is on a Giant XTC 29er.

  10. #10
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    maybe he just likes not having to squeeze the lever as hard

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