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RevoPower’s Gasoline-Powered Bicycle Wheel

The Wheel’s basic design.

RevoPower, a Denver-based company, is developing a 2-stroke engine-powered replacement front wheel for bicycles. The 25cc hub engine in the Wheel delivers 1hp (0.8 kW) peak power at 7,500 rpm and supports a top speed of 20 mph. Fuel economy is an estimated 200 mpg.

The Wheel meets CARB/EPA standards for small off-road engines, and features an idle-stop function that cuts off the engine at speeds below 5 mph. (Conversely, the rider needs to hit 5 mph before the engine will engage.) By stoping the engine at low speed or rest, RevoPower avoids the issue of idling emissions, as well as the problem of cooling the engine when the wheel is not rotating.


The company has developed seven prototype engines, two hand-built and five from Komatsu. RevoPower is working with another manufacturer on a stratified charge two-stroke engine with port geometry that will meet the emissions requirements.

The Wheel itself weighs less than 15 pounds (5 kg), and uses a standard one-quart fuel tank (although other designs are possible). Noise emitted by the engine is less than 65 dB at a distance of 7.5 m.

Swapping out a conventional bike wheel with the powered Wheel takes about 30 minutes. The Wheel will be available in 2007, and will cost about $400.

RevoPower has put about $1M into the development of the Wheel so far, and is raising an additional $3-7 million.

(A hat-tip to Richard Earl!)



Tony Flecchia

The concept is very much older than the 1987 mentioned above. In the 1950s we were selling and servicing the Dutch made Cyclemaster wheels. The first model was 25 cc two stroke within a rear wheel with a pressed steel hub drum painted black, but it was very underpowered. This was quickly replaced with a 32 cc version in grey paint to distinguish it. The petroil tanks were also within the wheel. Slightly later but still in the '50s, BSA took up the idea and produced their own version which they called the Winged Wheel. This was 50 cc and the cylinder and crankcase lay horizontally alongside the hub drum just below the bicycle left frame lower tube, all other parts and fuel tank inside the wheel. All the models netioned transmitted the drive to the hub by a chain. None of these were very long lived and by the early '60s had disappeared.


Unfortunately, it appears this thing will never be sold. It was supposed to be ready for sale in 2007 and it's now 2008 and no news. The site's main page says "join our email list for updates" but there is no link to do so. I envision the company will go belly up and the product will never make it to the street. Too bad they decided to get a nationwide dealer network set up instead of selling it directly themselves. That just complicated matters too much.

Ken King

A statement was made that 2 stroke engines were dirty engine's and created high emission's, well some of them do have high emission's and then there are some that create
less emission's then a modern four(4) stroke automotive engine. ie: Mercury Marine's Opti-Max 2 stroke engine is legal on any body of water that allow's 4- stroke equipped watercraft and this include's the state of California whom is real tough on emission's. You need a better argument especially when gasoline will hit $4.50+ a gallon this summer.


Four strokes also use oil in the crankcase and yes all
motors burn oil!! The only reason a four stroke seems
to not burn oil is that it is replaced by condensation
and unburnt fuel leaking down and replaces the volumes
that get past the oil rings and past the valve guides.
If some oil didn't get into those areas it would wear
out way too fast. Also a 4 stroke that is tuned to be
a high output motor is working close to the design limit
and a look at MX bikes will show they need to be rebuilt
alot sooner then a 2 stroke and of course more parts to
be replaced which takes more resources(metal) fuel to
get the extra parts to distributors etc. more manufacturers to make the individual parts. more packaging etc etc etc. So what is the total footprint
of each type of motor when you figure in the total cost
of maintaining them, making and using?
There have been many improvements in 2 stroke design
and the high pressure fuel injection that marine engines
ar using is one of the most promising. A supercharger
and turbo to force air into the motor can do away with
the crankcase induction and allow it to use a sump oil
system like a 4 stroke and not have to burn and waste
the oil.

Domenique Hawkins

Such items are both wonderful and innovative. As far as the pollution issues are concerned the 2 strokes could be converted to use natural gas or propane. Such a device could even use the proper mix of alcohol and castor oil like small/model airplane engines/radial engines of WWI. But until lead acid battery technology improves (build them to last not for profit by incorporating desulfating tech) I wouldn't rule any of these out. Even the manufactures of 2 stroke oil could use alcohol to make their blends less harsh. Great article and comments.


re: revopower wheel - any comments on how the engine exhausts? As it spins around the front axel, the exhaust pipe also must move. Does it spray out backwards in the slipstream all over your pant legs?

If so, too bad it isn't made for the rear wheel: many successful "powered wheels" were made in the 1950s, but were heavy. Revopower does have the advantage of light weight. Is it for sale yet? They seem reluctant to return correspondence - I've sent a few with no response.

Two-strokes can be fairly "clean" if fitted with disc or reed valves, and if the engine is engineered well it can also use a higher fuel/oil ratio (some run on 50:1), thereby cleaning up the emissions. Some cheap Asian four stroke scooters on the market run like a bloody diesel despite claims of clean emissions and great fuel economy. With only 30+cc to play with, I don't think the RevoPower would be all that much of a threat.

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