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Goofy question: 650c wheels on my mountain bike?

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Goofy question: 650c wheels on my mountain bike?

Old 03-18-11, 09:34 AM
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FastJake
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Goofy question: 650c wheels on my mountain bike?

It seems like the time trial/tri crowd is starting to ditch this size. Prices for these wheels seem to be lower than, for example, a comparable 700c wheelset. I like making stuff work that wasn't supposed to and I think it would be fun to put a set of skinny tired 650c wheels on my commuter MTB. If my calculations are correct I'd only need to move the brake pads up 6mm. This seems do-able with my cantilevers.

Is this a dumb idea? Anything else I should know? I will only do this if I can get a really good deal on a wheelset.
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Old 03-18-11, 09:46 AM
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if the brakes reach, you've cleared the only real hurdle to the change. The other will be rear axle width, typically 130mm on wheels intended for road, vs. 135 for mtb.

One thing to consider is that 6mm is a fairly big percentage difference on cantis or V-brakes, so there will probably be a noticeable loss in leverage. Not an issue if you have strong hands, but may be if you're already less than thrilled with your braking.

The other consideration is that horizontal post to rim distance affects canti and V-brakes. The posts are fitted to the fork based on an assumption of what rim width will be. If your rims are much narrower it may become an issue, but you can correct for this with thicker shoes and/or spacers between the shoe and brake arm.

As I said there's no major hurdle, so if the minor drawbacks are acceptable to you, it might make sense for a commuter.
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Old 03-18-11, 11:12 AM
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The rear hub width issue would be the deal killer for me doing such a thing. It's one thing to do stuff because it's fun to tinker but this seems like a lot of fiddling around with axle spacers to get the privelage of buying expensive tires.

A more practical solution would be to just get either the Conti 26x1's or Panaracer Pasela 26x1.25. The Pasela sounds too wide but it fits on with a very pointy "egg" shape when mounted and the tread face arc shape is pretty much the same radius as you'd get with a 700x23 or 25 tire.
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Old 03-18-11, 03:03 PM
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Thanks for the tips guys. The axle spacing doesn't bother me; I've messed with that before on other wheels without any real problems.

I'd only do this if I could get a set of wheels or wheels/tires super cheap. I already have a set of slick 26x1.4 tires, so it's not like I "need" another wheelset. If I ever find an old used set of 650c's I'll resurrect the thread and post some pictures.
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