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  1. #1
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    Disc diameter dilemma...sizing help?

    I weigh 220 lb. I ride ski area DH and long trail rides. I'm putting together a DH/trail bike. It is a KHS FR2000 with 4-6 inches of Romic travel. In due time, I plan to put a late model Z1 with 20mm axle on the front.

    I will be going with Avid mechanicals. I have three combinations in mind:

    1) 160mm rear and 185mm front
    2) 185mm rear and 185mm front
    3) 185mm rear and 203mm front

    I am leaning towards option #1. I've been riding MTB for 15 years and think of myself as a finess rider; if that has anythign to do with it.

  2. #2
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    I would go for #3.

    220 lbs and ski area shuttle runs say 203 in front to me.

    I am using 203/185 Avids on my Coiler De Lux. Easy to adjust the brake power.
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  3. #3
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    I'm 230 lbs. and say go for option #4 203 front and rear.
    Quote Originally Posted by shiggy
    I would go for #3.

    220 lbs and ski area shuttle runs say 203 in front to me.

    I am using 203/185 Avids on my Coiler De Lux. Easy to adjust the brake power.

  4. #4
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    Gosh thanks...

    But, wouldn't a 185 in the back give me a more "balanced" feal of bracking force? Or do I need even force like what rim brakes deliver?

    Did I mention Angel Fire has 2200 feet of lift-serviced vertical drop? So, I suppose larger discs means more heat disipation and longer pad life? And, what the hey, the 203's cost the same as the 185's.

    Anyway, whats 1 or 2 ounces more of steel when I'm riding the west rim of the Rio Grande after it saved my ass up on the slopes of Angel Fire? I suspect that its only a matter of time before I'm pushing what I've got to its limits. So I might as well plan to go big and go fast.

  5. #5
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    I ride Whistler a lot in the summer. I tried smaller rotor rear, large front. Found that the bigger disks on both ends dissipate heat better.Go 203's.
    Quote Originally Posted by long_strange_ride
    But, wouldn't a 185 in the back give me a more "balanced" feal of bracking force? Or do I need even force like what rim brakes deliver?

    Did I mention Angel Fire has 2200 feet of lift-serviced vertical drop? So, I suppose larger discs means more heat disipation and longer pad life? And, what the hey, the 203's cost the same as the 185's.

    Anyway, whats 1 or 2 ounces more of steel when I'm riding the west rim of the Rio Grande after it saved my ass up on the slopes of Angel Fire? I suspect that its only a matter of time before I'm pushing what I've got to its limits. So I might as well plan to go big and go fast.

  6. #6
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    Quote Originally Posted by long_strange_ride
    I weigh 220 lb. I ride ski area DH and long trail rides. I'm putting together a DH/trail bike. It is a KHS FR2000 with 4-6 inches of Romic travel. In due time, I plan to put a late model Z1 with 20mm axle on the front.

    I will be going with Avid mechanicals. I have three combinations in mind:

    1) 160mm rear and 185mm front
    2) 185mm rear and 185mm front
    3) 185mm rear and 203mm front

    I am leaning towards option #1. I've been riding MTB for 15 years and think of myself as a finess rider; if that has anythign to do with it.
    You might want to check with your LBS about whether your hubs and fork can handle the larger rotor. Some can't, and there have been some recalls. A front end failure during a steep decent is not something you'd enjoy. Good luck. - Dave

  7. #7
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    There is only one option. Dual 203s. No need to mess with the small stuff, you'll just end up on 203s anyway. They work better in all conditions. Better modulation and less finger strain. Plus if you taco a rotor, good luck finding a replacement 185, but just about any bike shop will have spare 203s in stock.

  8. #8
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    Quote Originally Posted by dnpeters
    You might want to check with your LBS about whether your hubs and fork can handle the larger rotor. Some can't, and there have been some recalls. A front end failure during a steep decent is not something you'd enjoy. Good luck. - Dave
    The lowers of my current Marzocchi are aluminum; not magnesium. They have standard IS mount.

    I will start with a pair of Nashbar wheels with Shimano M525s on both ends. I will convert the front QR axle to a solid BMX bolt-on type for extra strength. Later I will build up a 20mm front hub and use it on a new style 20mm Marzocchi (either dedicated 20mm axle or "pinch-bolt" QR style).

    Thanks for the input.

  9. #9
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    Quote Originally Posted by long_strange_ride
    The lowers of my current Marzocchi are aluminum; not magnesium. They have standard IS mount.

    I will start with a pair of Nashbar wheels with Shimano M525s on both ends. I will convert the front QR axle to a solid BMX bolt-on type for extra strength. Later I will build up a 20mm front hub and use it on a new style 20mm Marzocchi (either dedicated 20mm axle or "pinch-bolt" QR style).

    Thanks for the input.

    Sounds like you've done your homework. You may find the larger rotor is more susceptible to the mysterious shing-shing noise; mine was. Good luck. - Dave

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