The E-Bike Revolution is Altering the Bicycle Market

This article is an excerpt of a feature story from the February 2025 issue of Mechanical Engineering magazine.

I used to not give electric bicycles a second thought. These battery-powered bicycles—e-bikes, as they are called—look like fully human bikes, except for the strange sight of people breezing along a street with pedals in motion but hardly breaking a sweat.
 
A closer inspection reveals some key differences. E-bikes have an electric motor and battery pack attached to the frame (or sometimes in the frame) for extra power. A small pad mounted on the handlebars enables the rider to control the power to the motor, and it displays the amount of charge left in the battery. Riders can apply the motor power many ways in any amount, in conjunction with the gears—all the time on flat and uphill stretches to increase overall speed or in bursts to overcome only the steepest sections of the route.
 
As an experienced cyclist, I had no need for advances in batteries or power control systems and had no problem keeping up with other riders on my analog bike. That is, until a health crisis made riding a conventional bicycle almost impossible. After that, my wife and some friends convinced me to purchase an electric bicycle. And I went from a skeptic to a convert
 
Adam Mercier, co-founder of LMX Bikes, a French manufacturer of mountain e-bikes, told me, “It can level the playing field and get a lot more people on bikes and more people out on the trail.” That’s definitely been my experience.
 
People always want to know, “How far can you go on that thing?” Most e-bikes average 30 to 120 miles on a battery charge. The range of an e-bike charge depends on factors such as rider weight, wind, hills, and how much pedal assist or throttle you choose. Pedal assist engages the motor when the rider pedals, while throttle control turns on the motor regardless.
 
A torque sensor built into the system senses your output and controls the motor’s power to match. This process relies on the controller to give instructions to the motor, so it supplies an appropriate amount of power. The controller determines how much power to provide by interpreting information from a cadence sensor in addition to the torque sensor.
 
The motor only kicks in if the torque required is less than the rating of the motor (mine is a moderate 50 newton-meters).
 
Another design choice involves the location of the motor itself. For instance, hub motors, including direct-drive and geared, mount inside the rear wheel hub, while mid-drive motors are geared and mount to the crankshaft at the pedals. Mid-drive motors offer better balance and weight distribution because of their location at the middle of the bike. Those advantages have made mid-drive motors the most popular design.
 
Most bicycle companies outsource their drive units. 
 
“We source the battery cells from different manufacturers and assemble them ourselves,” Mercier said. “We also assemble the drive units.”
 
 “We buy most motors, batteries, and electrical components outside,” said Chris Carlson, director of e-bikes at Trek Bicycle in Waterloo, Wis. Bosch supplies batteries as part of its drive systems, and Yamaha also makes drives.
 
Manufacturing e-bikes required a few changes to the processes and parts used for existing bikes.
 
“There are some additional forgings and castings for the drive system, manufacturing it so you can fit the battery down inside the tube,” said Chris Dodman, a principal research engineer who started the e-bikes program at Cannondale. “We developed the battery with Bosch that could be integrated into frames. That requires more tube manipulation.”
 
In addition, Dodman said, “We integrated larger spline and shaft sizes to handle the torque. We worked with Bosch to get the right feel of the drive.”
 

Market shift 

While most reputable e-bike manufacturers are established blue-bloods and rely on fairly conventional designs, Adam Mercier has taken a startup entrepreneurial approach. He went to school at Insi in France to study mechanical engineering, specializing in product development and innovation.
 
“I worked at different companies through the school as an intern part-time. I was building this company,” he said. “I built my own drive system, my own motor.”
 
Mercier built the first prototype 15 years ago using batteries he brought from DeWalt. “During engineering school, I was always building prototypes,” he said.
 
Mercier and his co-founders bought an existing company and sold shares a few years ago. Now they’re backed by a company that makes Formula E racecars. LMX Bikes designs and manufactures supercharged electric mountain bikes out of their workshop in Jonage, near Lyon, France.
 
“We tried to open a new category between a bicycle and a motorcycle,” Mercier said.
 
Their flagship LMX 56 has both pedal assist and a handlebar throttle with two independent transmissions. It has a chain on the pedal side and a belt on the other side. This patented double freewheel transmission system allows total independent “bicycle” and “motorcycle” modes.
 
Other companies are reexamining the design of their electric bicycles to take better advantage of what new technology can deliver.
 
To read more, see “E-Bike Revolution” in the February 2025 issue of Mechanical Engineering magazine.
 
Tom Gibson, P.E., is a consulting mechanical engineer in Sugar Grove, Va., specializing in machine design, sustainability, and recycling and a freelance writer specializing in engineering, technology, and sustainability.