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Motorized Cargo Bike

When/if the price of gas hits $10 or $12 per gallon, I'm guessing bikes like this could be popular. Nothing like being able to haul a bale of hay up a steep hill while getting over 100 mpg. After building the first version of my motorized Raleigh 20 that could haul 2 bags of groceries, I thought it would be handy to have a motorized bike that could haul lots of stuff. This one has a bed made of white cedar that measures 23" by 36" inches. As you can see in the picture above, it handles 2 tanks of propane and some sack feed well. That's a 25 lb. bag in the picture. The 49cc Dax Titan 4-stroke engine provides plenty of power for this bike, even heavily loaded up steep hills. This bike, like the Raleigh and my motorized recumbent uses a jackshaft to route both pedal and engine power through the bike's freewheel and gears. A 6-speed freewheel that works well on steep hills, yet yields high speeds on flat roads. I have yet to measure the maximum speed, but I'm sure it's over 30 mph.

Just got back from Cenex with 2 5-gallon propane tanks and a bag of chicken feed.

Side view showing the engine position below the cargo bed with the jackshaft below the engine.

Front view showing the suspension fork, a brake lever on the rider's right side for the throttle, and the gear shifter on the rider's left side.

Rear view showing the cargo bed with its stepped sides, and the center stand.

A close up of the engine. DAX supplies a 5:1 gear reducer that uses an oil bath. It seems well made and is quiet. The drive cog has 10 teeth and drives a standard 1/8" bike chain. The big black disk is the freewheeling large cog driven by the 10 tooth cog. It must freewheel in order to allow the rider to pedal without turning the motor. The front crankset and chainring drive a BMX freewheel seen in near the center of the jackshaft, and a standard coaster-brake style cog then drives the rear wheel's freewheel.

A veiw of the jackshaft from the rear. The various chains are more visible in this photo.

Left side of the jackshaft showing the sealed bearing and the end of the 5/8" steel shaft. In retrospect I know how to make this whole jackshaft assembly much simpler.

The inside of the freewheeling large cog. Basically I sandwiched the cog part of a BMX freewheel with two aluminum disks, and then bolted the chainwheel to one of the disks. The BMX freewheels are mounted on the 5/8" jackshaft with one of Staton Inc's freewheel adapters

An outer view showing the two aluminum disks, and a shaft collar securing the freewheel adapter on the shaft.

This bike requires a center stand. This view shows it in its lowered position. Note the adjustable elastic cord that pulls it up when the bike is rocked forward.

Center stand in the up position.

Front chain tensioner, drilled for lighter weight.

The engine comes with a gas tank, but I wanted more range, so I switched to a standard 1 gallon gas tank.

On/off switch and pull start handle mounted up front so the rider's more likely to kill the engine when not needed (stoplights and down hills).

A detail shot of the struts that support the cargo bed.

The swiveling rear engine mount.

The front engine mount can raise and lower via the repurposed bike axle nuts, thereby tightening and loosening the chain between the 10 tooth cog and the freewheeling chainring.

The 23" x 36" cargo bed made from rot resistant white cedar.