Riding a bicycle on busy streets full of motorized vehicles can be risky enough in the daytime, but it potentially becomes even more dangerous at night, when motorists are less likely to see cyclists. Much of that risk can be minimized by using a bright headlight and strobing taillight, although those don't do much to increase a cyclist's visibility when seen from the side - and even if they did, there's no such thing as being too bright. Two separate projects, however, are aimed at developing systems that would allow a bicycle's wheel rims to act as running lights that would be hard not to notice.

Carnegie Mellon University industrial design sophomores Jonathan Ota and Ethan Frier are currently using a research grant to develop their Aura system. It incorporates six groups of three tri-color LEDs embedded into both rims, that are powered by a dynamo generator built into the front hub. The rims start out appearing as two red circles when the bicycle is moving slowly, but transition through to white as it gathers speed. A handlebar-mounted power switch allows riders to turn the system off when riding in the daytime.

The two students are presently working towards commercializing Aura. "We wanted to make a cool product that people will want to use, and in the process of using it, will make them safer," said Ota.

Below is a video that shows their invention in motion.

Over in California's Bay Area, meanwhile, inventor Kent Frankovich and partners Adam Pettler and Jim Houk are refining their Revolights system. It consists of two hoop-like assemblies each containing eight LEDs, that clip onto a bicycle's existing rims. Powered by hub-mounted lithium-ion battery packs, the lights blink on and off at a rate set by the speed at which the wheels are turning - this blinking pattern, in turn, results in the front half of the front wheel and the rear half of the rear wheel being illuminated. This means that a bike running Revolights looks rather like a pair of bright parentheses, traveling down the street.

Unlike Aura, which is meant to be used in conjunction with regular head- and taillights, Revolights is intended to serve as such lights. The system is designed not only to provide side illumination, but also to project light in front of and behind the bicycle. The front set of white LEDs produces a combined output of 134 lumens.

Frankovich and company are now in the process of raising funds from prospective customers for commercial development of Revolights. They expect it to be available by the end of the year, for a suggested price of US$220.

Should you want your lit-up rims right now, however, there are already various companies selling LED valve stem caps, along with LEDs that attach to the base of the spokes.

The Revolights pitch video, which includes shots of the system in action, can be seen below.

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