A Wider Rim ExperimentRunning front suspension on a street bicycle also reduces the forces acting on the front wheel, allowing it to be lighter. To lighten the front with maximum effect for acceleration and deceleration, and the least cost, put on a smaller tire. There are several models of matching dual sized 26” street tires, Continentals, Ritcheys, Tiogas... But then there is a problem with equal width rims and a wider rear tire. The noticeable feel when cornering is that the wider tire will laterally roll over more than the narrow. Resulting in squirrelly control. Sports car enthusiasts call this phenomenon yaw. To reduce this, the rear rim needs to be wider so that the tire beads are farther apart, and the tire section width is “unrolled”. Unfortunately, wider rims contain more metal and put unnecessary weight right where I do not want it. I remember old school BMX cruiser racers drilling out their rims and I see current pro trials riders with super wide rims and giant holes drilled thru the rim bed between every spoke. Seeing these examples of tough use and survival, and then making qualitative calculations, I can deduce that the round hole does not eliminate the structural integrity of the rim.
I figured that drilling out only the inner wall of a double wall rim would further ensure the strength of the finished rim. I chose the strongest lightest widest best-priced rim I could find, Ryno Lite XL. I got a large drill bit, marked my locations, and drilled out those rims. I had my vacuum cleaner handy for pulling out aluminum chips that tried to stay inside the rim.
Taking out two holes between each spoke, I was able to remove about two ounces of material. Not a huge amount, but significant. Now the wide rim weighs like a narrow rim. I use fiber reinforced packing tape for a rim strip and it really became useful for this project. Using a 650c inner tube and my 100 psi tire; after much riding, the rim shows no signs of weakness.
The handling improvements with the wide rear rim are unquestionable.
Cornering is super solid, predictable, and controllable. |
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