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  1. #1
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    Making the jump to disc brakes

    So like the title says I am making the jump to disc brakes, I have XT levers and V's and am thinking 203mm BB7's will do the trick.Something else I have been wondering is if there are ways to convert a sandard hub to a disc hub, and if a standard hub can be modified to be a 20mm hub.

  2. #2
    The Mud Stud
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    Umm, I think some hubs can be modded, if they are designed for it. Ive heard of this remotely. In 2 words. BAD IDEA. On the 20mm hub, no, pretty much impossible as far as I know. As to the 203mm rotors with the xt levers. Yea, that will work pretty well (really well).

  3. #3
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    thanks for the tip

  4. #4
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    Something to keep in mind about rotor size is if you have more than you need it isn't really a good thing.
    Size depends on what type of riding you will be doing, and how much you weigh, and how big of rotors will your frame and fork handle. Some forks will only handle a 185mm rotor.......some older forks will only handle a 160mm. Most forks designed for AM/DH/FR will handle the big rotors no problem, where a lightweight XC fork may only handle a 160 or 185 max. Also, will the larger rotor clear the chainstays of the frame?.
    If the rotors are too big you will have an "on/off" fell, meaning no modulation.
    If you weigh under 200lbs and are doing agressive XC or AM type of riding a 7" front and 6 or 7" rear should work good. If you are a bigger person like I am you need the larger rotors otherwise your brakes will heat up too fast and will fade easy.
    I'm almost 300lbs and I run a 203mm front and a 185mm rear. I ride agressive XC leaning more toward the AM side of things and this combo works great.
    On my commuter bike I run 160mm BB7's and can toss myself over the bars no problem if I wanted with 2 finger braking.
    My point is, don't get too much brake, as you will lose all feel.
    Look, whatever happens, don't fight the mountain.

  5. #5
    local trails rider
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    Agreed: if you dont have a particular reason to go for the BIG rotors, don't.

    I am probably over 200lbs and my Shimano LX hydraulics with 160mm rotors are good for one finger braking on my "rough XC" rides. I do not have opportunities for extended downhilling where overheating could become an issue, though.

  6. #6
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    cool thanks for the advice I think I'll stick with the big rotors based on what you are saying.

  7. #7
    local trails rider
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    Do the big rotors fit in your frame?
    Do frame and fork manufacturers approve the use of big rotors?

  8. #8
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    thanks fellas I am about 250-60 and am putting them on an 07 coiler. I hit the down hill sections pretty fast. I don't want to go hydraulics since I already have parts that work well.

  9. #9
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    "if there are ways to convert a sandard hub to a disc hub"

    In a word, no. The only way to accomplish this would be to replace the entire hub body. Not a cost effective way to get disc hubs. Hub bodies are realatively difficult to come by and rather expensive when you can find them. Plus you have to transfer the guts of the old hub over. Not a big deal with a front hub, but a bit of a PIA with the rear.

    "and if a standard hub can be modified to be a 20mm hub."

    Again, in a word, no. Unless the hub manufacturer specifically designed the hub to be convertable, like a Hope Pro II or the like, it's likely not going to be possible. In most cases a reqular QR hub won't have an opening in either end of the hub shell large enough to put a 20mm axel through. And I won't even get into bearing seat and size problems, component availability etc.

    Bottom line is, if you don't have disc wheels with a 20mm thru front hub currently. Get a set. It'll be easier and much less hassle in the long run. It probably won't be cheaper, but the results will certainly be much more predictable.

    Good Dirt
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  10. #10
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    What's the approximate cost to convert from rim brakes to hydraulic discs? I'm a 195# 2nd season (beginning) XC rider. Thanks!

  11. #11
    local trails rider
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    Depends on if you need new wheels (hubs). Frames and forks usually have the attachments for disk brakes.

  12. #12
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    Quick ballpark idea if you need new wheels too, usually about $300-400 starters if you shop for closeout deals.
    Jenson has a WTB dual duty wheels on sale for $89 i think, and hydros as low as $30 each. So if you went with THE cheapest closeout stuff under $200.
    But at 200lbs I wouldn't use those wheels. You're wanting to spend about $200 on a closeout wheelset.
    Look, whatever happens, don't fight the mountain.

  13. #13
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    Quote Originally Posted by slipry
    What's the approximate cost to convert from rim brakes to hydraulic discs? I'm a 195# 2nd season (beginning) XC rider. Thanks!
    As the others have said, there is a HUGE range in price and quality. And in this case as many others, you'll get what you pay for. Wheel sets can be had fairly cheaply, but most of the bargain bassement prices are going to be on lower end wheel sets, and they won't be the lightest or the strongest. Some brakes can be had fairly cheaply by comparison right now as manufacturers bring out new models or update current models and stores blow out the old stuff to make room for the new. Right now you can go from cheap low end hydros on close out for $30 to high end stuff at $300 a wheel. Just depends on your budget. If you need wheels the sky is pretty much the limit. Again, depends on what you want and your budget.

    The average for a full disc conversion with wheels is right around $400 to $700. Not saying you can't go lower, but that's what most folks spend in the process without going to the bargain basement low end stuff and getting reasoable quality components.

    Good Dirt
    "I do whatever my Rice Cripsies tell me to!"

  14. #14
    local trails rider
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    A pair of decent brakes does not have to cost a huge amount of money. So far, my pair of Shimano LX hydraulics has been treating me well, and I hear other brakes in that price range are quite good too.

    I also have a pair of mechanical disc brakes on one bike and I much prefer the feel of the hydraulics. My V brakes feel better than the mech discs I have... must be the shorter and simpler cable runs.

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