Rims - how wide for DH bike park uses?- Mtbr.com
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  1. #1
    Reputation: derby's Avatar
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    Jan 2004

    New question here. Rims - how wide for DH bike park?

    Do you mix rim width? Wider rear or wider front, if so why?

    Aluminum rims tend to have 5 to 6mm narrower inner-width from the outer-width, from what I've measured.


    Edit added:

    Thanks for the reply's! Personally I've been trail riding and occasional DH park with Velocity P35 front (35mm outer, 30mm inner-width) and Blunt (28mm outer 23 inner-width) rear rims, 600g front, 500g rear measured weight (650b rims). I'd like a 40mm outer-wide front with 35mm outer-wide rear for the rocky trails I like to climb to descend. Using the same tire front and rear, the faster wearing rear on a narrower rim flattens the center knobs to match the slower wearing front on a wider front rim. And overall with newer tires the wider front rim an more square profile of the tire helps balance the grip since I feel the front washes out easier than the rear slides (without skidding).

    The problem for trail riding when it's smoother is the heavier weight of wider rims. For rock climbing I feel that heavier rolling weight is an advantage, but I'd rather put the weight into heavier tires, not the rims, for those conditions. I want carbon fiber extra-wide 35 and 40mm outer-wide rims under 500g each.

    I'm trying some Light-Bicycle.com 30mm rims (23mm inner-width) now at 360g weight. I miss the wider front rim feel. These can be built with much stiffer spoke tension than any aluminum rim without cracking, but will they be durable to flatting and hitting rocks and flying rocks and crashing hard on rocks without crushing or cracking, that now dent and bend my aluminum rims?

    Will extra-wide 30mm inner-width at 425 to 450g or 35mm inner width at 475 to 500g per rim be durable enough for DH and FR pounding rocks and crashes?

    I found these earlier threads on wide rims that relate closely:

    wiiiide inner width rims? What's out there? - Mtbr Forums

    Syntace Rolls Out Lightweight “But Tough” Mountain Bike Wheels w/ 25-40mm Wide Rims! - Bike Rumor

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    Last edited by derby; 10-31-2012 at 07:59 PM.

  2. #2
    mtbr member
    Reputation: bullcrew's Avatar
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    Jan 2005
    Use what keeps the tire profile correct for the width tire you are using.
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  3. #3
    Slap happy crappiness
    Reputation: DHgnaR's Avatar
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    Feb 2008
    Quote Originally Posted by derby View Post
    Do you mix rim width? Wider rear or wider front, if so why?

    Aluminum rims tend to have 5 to 6mm narrower inner-width from the outer-width, from what I've measured.

    You can mix rim width if you want, but you generally will see people mixing tire width more than rim. In the case of tires, you want a wider front than rear, or equal front and back. I tend to stick to 2.5 Maxxis tires, so 2.4 for most other brands, front and rear. For Mammoth where it's really really deep kitty litter, I run a 2.7 front.
    As far as rim width, you'd wanna prob stay between 21mm and up for DH; that's inner rim width, not outer. But rims that are burly enough for DH are usually pretty wide, with Mavic EX823's and EX721's being the exception, being 23mm and 21mm respectively.
    I'd rather have a bottle in front of me than a frontal lobotomy.

  4. #4
    mtbr member
    Reputation: Hardtails Are Better's Avatar
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    May 2005
    What DHgnaR said. Happily running Mavic 721s, but they are on the narrow side. I've used stuff between 21 and ~27mm internal.

  5. #5
    Custom Wheelbuilder
    Reputation: Zen Cyclery's Avatar
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    Mar 2009
    I think that a wider rim up front is only going to help handling. It allows tires (especially the fatter 2.5-2.7 range) to sit in a more natural shape which will make cornering more predictable and consistent.
    But as mentioned, changing up your tires is a much cheaper and easier way to change the characteristics of your rig, rather than getting new rims.
    Check out www.zencyclery.com for fully customizable, handbuilt wheels.


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