tiny wheels pt. 2

I came across this image of a road bike with mtb tires on the fixed gear gallery and wish I could test ride it. If anybody has tried this, I am curious what they found.

benjaminlemar-1.jpg

Some people say that it makes the handling a bit awkward on turns. If that is not true, it would be a great conversion for 70s frames (Schwinn, Univega, Fuji, Peugot, Cenurion, etc.) whose rims are too heavy, rusty, and slippery in wet weather to be of much use.

To convert a road bike to smaller and wider rims/wheels one would first have to measure the width of the chainstay tube and fork. There would also be an issue of the rear hub not being not sized appropriately. This may not be an issue with rear rims that accept 5-7 speed freewheels, though I have not tried. If everything was OK wiht frame spacing, then next get some long caliper brake levers. For more info see Sheldon’s post, rest in peace.

The consumer analog are these 650Bs (588mm) being used on bikes by Rivendell, Ira Ryan and Kogswell Cycles– all seemingly fantastic frame makers. 650Bs are a comfortable middle ground between 700c (622mm) and 26” mtb (559mm) and provide the same wheel height as 700c with more tire volume and width. My only concern is that 650Bs are expensive and uncommom, and therefore difficult to replace and are not recyclery material yet. On my own bike, a 1974 Raleigh, there are 650A (590mm) rims that are pretty shot, but I am scared to take them off lest I cannot find another. I think the previous owner of the Raleigh also had the same issue, because the rims were rebuilt by the looks of the variegated nipples.

Why are the best things in life hard to come by, or are they hard to come by SO they are the best things? Can cheap second-hand mtb rims/tires be the next 650B-esque conversion for thrifty vintage road biker? The fixed gear rider from Tel-Aviv (pictured above) seems to think so. At the very least, I hope that these big volume road bike conversions help ease the spandex fad and bring road biking back from the podium to the pavement.

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3 responses to “tiny wheels pt. 2

  1. A lot of those 70s and 80s 10-speeds were designed for 27″ wheels. Using 700C instead gets you about 4mm more clearance. That may not be much difference for tire size, but it’s just enough to add fenders. The difference in handling is negligible and rim brakes can usually be adjusted to work. I have done this on both my Schwinn fixed-gear and Univega tourer.

    I don’t think the bike pictured there is the result of a wheel-size conversion (it’s not a fixed-gear either) – just a coaster brake cruiser with old-fashioned geometry.

    The size difference between 27″/700C and 26″ might be a bit too much to make a conversion practical. Brake reach is one issue. You’d need either a caliper with 80mm or more reach (I’m not sure one exists), new cantilever bosses brazed on, or hub brakes (disc/drum/coaster). And tire clearance will still be limited by the width of the fork and chainstays, so you probably couldn’t fit anything wider than what you could converting to 650B instead. Then there is the issue of steering geometry and bottom bracket height…

    So yeah, it’s too bad 650B hasn’t caught on yet. Here’s one conversion that got me thinking:

    http://www.fixedgeargallery.com/contest/2008-opendesign/NilsSandin.htm

  2. what a great idear. i think in a few years we will see more 650Bs… all it takes is one corp. bike company to do it, and there will be tons of used rims when those corp. bike buyers ditch their ride in favor of the next year model.

  3. Measuring a wheel is not as easy as it seems. You need to know what the measurements of the rim mean and how this corresponds with the tire size. The usual method is to measure the outside of the tire, so in inches that would be 24″, 26″ or 27″ and in metric that would be 600, 650 or 700.

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