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Thread: 29er = 700c?

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    Senior Member Btflmutant's Avatar
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    29er = 700c?

    I'm looking for a new wheelset for my Cannondale T200 and I'm confused about wheel sizes. My rims are 700s but the hubs are LX. Are these 29ers?

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    <3s bikes Re-Cycle's Avatar
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    29er is a marketing term for mountain bike 700c. You could take high zoot road wheels and put them on a 29er mountain bike provided the hub width wasn't an issue. Generally 29er rims are wider and therefore require wider tires.
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    biked well well biked's Avatar
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    Quote Originally Posted by Btflmutant View Post
    I'm looking for a new wheelset for my Cannondale T200 and I'm confused about wheel sizes. My rims are 700s but the hubs are LX. Are these 29ers?
    This has nothing to do with the "29er" issue, that's already been answered, but one thing the LX hub implies is that the axle spacing on the rear hub is 135mm, which is the current mtb standard. Your Cannondale touring bike may have dropout spacing of 135mm, or I believe there are some Cannondale touring bikes with 132.5mm dropout spacing. You should check this, if the rear dropout spacing is 132.5mm you'll be able to easily use road hubs or mountain bike hubs. If it's 135mm dropout spacing, it would be best to stick with a mountain bike hub.

    FWIW, mountain bike hubs, and their 135mm axle spacing, are popular on touring bikes because all other things being equal, the wheel will be a bit stronger because there's less dish required with the wider spacing-

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    Insane Bicycle Mechanic Jeff Wills's Avatar
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    Quote Originally Posted by well biked View Post
    FWIW, mountain bike hubs, and their 135mm axle spacing, are popular on touring bikes because all other things being equal, the wheel will be a bit stronger because there's less dish required with the wider spacing-

    I agree- less dish makes for a stronger wheel. I've rebuilt Shimano "road" hubs with longer axles and a 5mm spacer on the left side to make them 135mm OLD. This has worked fine on 105 and Sora hubs- I don't doubt it would work on anything except the later Dura-Ace hubs. The resulting wheel, built with 36 double-butted spokes, is bombproof.
    Last edited by Jeff Wills; 11-08-08 at 05:49 PM.
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    Perineal Pressurized dobber's Avatar
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    Quote Originally Posted by Jeff Wills View Post
    I agree- less dish makes for a stronger wheel. I've rebuilt Shimano "road" hubs with longer axles and a 5mm spacer to make them 135mm OLD. This has worked fine on 105 and Sora hubs- I don't doubt it would work on anything except the later Dura-Ace hubs. The resulting wheel, built with 36 double-butted spokes, is bombproof.
    Spacing out a road hub won't do diddle for the dish, the flanges are still the same distance apart. In fact, you'll have a weaker wheel as you have a longer axle without the benefit of the bearing being spread further apart.
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    Jonnys ilegitimate Father cavernmech's Avatar
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    Quote Originally Posted by dobber View Post
    Spacing out a road hub won't do diddle for the dish, the flanges are still the same distance apart. In fact, you'll have a weaker wheel as you have a longer axle without the benefit of the bearing being spread further apart.
    Adding a 5mm spacer to the nondrive side of a wheel would require the rim to be moved back to the left side. Therefore moving the rim towards the center of the hub...therefore lessening dish. The flange stance of the spokes remains the same but the tension would be more even.
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    Insane Bicycle Mechanic Jeff Wills's Avatar
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    Quote Originally Posted by cavernmech View Post
    Adding a 5mm spacer to the nondrive side of a wheel would require the rim to be moved back to the left side. Therefore moving the rim towards the center of the hub...therefore lessening dish. The flange stance of the spokes remains the same but the tension would be more even.

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    (I've edited my original post to clarify.)
    Last edited by Jeff Wills; 11-08-08 at 05:50 PM.
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    Real Men Ride Ordinaries fuzz2050's Avatar
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    The flange spacing is about the same, looking at a shimano ultegra and LX hub I have.

    The real fun comes in when you switch to metric sizes, a 29er wheel has a bead seat diameter of 622mm. a 27 inch wheel has a bead seat diameter of 630mm, so a 27 inch wheel is larger than a 29 inch wheel (Yes, i know, tires, but it's more fun this way)

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    Senior Member Btflmutant's Avatar
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    Thanks for all the help, everyone.

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    Senior Member DannoXYZ's Avatar
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    Quote Originally Posted by dobber View Post
    Spacing out a road hub won't do diddle for the dish, the flanges are still the same distance apart. In fact, you'll have a weaker wheel as you have a longer axle without the benefit of the bearing being spread further apart.
    To calculate dish, measure the following distances:

    1. Ld = distance between left locknut surface and left hub-flange
    2. Rd = distance between right locknut surface and right hub-flange
    3. Wd = flange-width, distance between the hub flanges
    4. OLD = over-locknut distance (dropout spacing)

    Then dish is defined as:

    DISH = (OLD / 2) - [(Wd/2)+Ld] or
    DISH = [(Wd/2)+Rd] - (OLD/2) ; do it both ways to verify your calculations.

    Which is the distance between the flange-centres and OLD/dropout centre. Strongest wheel is when DISH=0. Most rear-wheels have 5-15mm of dish and offsets the rim to the side of the flange-centre in order to center it between the dropouts. This causes an imbalance of spoke-tension between drive-side versus non-drive spokes and results in a rear wheel that's not as strong as a front one. To reduce DISH, one would need to move the flange-center close to the OLD/dropout centre.

    One way is to design a 5-spd hub to move the right-flange to the right and put the flange-centre over the OLD/dropout centre. Another way is to increase OLD/dropout width while keeping the right-flange in the same location (by putting 5mm washer on left side). This moves the OLD/dropout centre to the left, closer to the flange-centre, thus reducing dish on the wheel and reduces the left/right spoke-tension differences for a stronger rear-wheel.

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