As we see each year at events like the North American Handmade Bicycle Show and Eurobike, bicycle designers will experiment with just about any style of frame. But they always seems to come back to the tried-and-true classic – the diamond frame. Perhaps, it's no wonder, then, that the e-bike industry is following suit. Propella is the latest startup to disguise its e-bike as a simple diamond-frame bicycle. Unlike a regular diamond-frame bicycle, this one has a versatile electric drive with both a throttle and a pedal assist system.

With its diamond frame-contained battery, 26.5-lb (12-kg) weight and small hub motor, the Freygeist Classic we looked at last month stands alone as the most classic, inconspicuous retail e-bike we've covered. But at €3,990 (about US$4,500), it's definitely not the most affordable.

Seattle's Propella Bikes shares a basic vision with the German folks at Freygeist – an e-bike that's more like a traditional pedal bike – but at a much more affordable price point. Its externally secured battery lacks the seamlessness of Freygeist's internal battery, but the rest of the Propella design is similarly clean and traditional. The small 250-watt rear hub motor blends in naturally, and the remainder of the bike looks the part of an everyday urban commuter, albeit with brightly colored rims and components.

The Propella e-bike has both a handlebar-mounted twist throttle and a pedelec system. The throttle, of course, lets the rider directly activate the motor, while the pedal-assist system offers five modes of motor assistance, selected via the onboard LCD computer. At a relatively light 36 lb (16.3-kg), the bike is also designed to be pedaled without any motor assistance at all, should the rider run out of battery power or want extra exercise.

Propella offers a broad range estimate of between 15 and 28 miles (24 and 45 km) and a top speed estimate of 20 mph (32 km/h). The 6.6 Ah Samsung lithium-ion battery takes about 2.5 hours to charge.

The Propella bike's aluminum alloy frame is dressed with a steel fork, Avid brakes, and 700 x 32 Kenda tires. Propella offers both single and six-speed drivetrain options, three frame sizes and four rim color options.

Propella is working to raise money on Indiegogo, with pledges as of writing starting at $699 (42 percent off estimated retail). The six-speed option is available as a $50 add-on. Shipping is available in the US only, and deliveries will begin from July/August, assuming everything moves along as Propella hopes.

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