Electric Bike Pedal Assist (Pedelec): Overview
Pedal-assist also referred to as pedelec, is a mode that provides power only when you are pedaling.
These machines have found favor in mainland Europe, particularly in countries where there is a strong existing cycling tradition.
‘Top-up’ electrical assistance is available when the rider pushes on the pedals. In other words, you must pedal to activate the ‘top-up’ power, although on most pedelecs you can still switch the power off and ride as you would on a ‘normal’ bike. This may be a little harder than normal, because the electric bike will be a little heavier, and the motor usually adds a little extra pedal resistance in one way or another.
There are also usually several power levels of assistance available and on the best torque-sensing machines (a term we look at below) ‘top-up’ assistance can be as little as 20% extra on top of your pedal effort of a whopping 300% of it, making it rather beyond the definition of top-up. At low support levels you generally get a pleasant, just noticeable helping push along the way and the highest levels on the most powerful mid-drives you get a superhuman push up the steepest hills, ideal for if you are in a rush and don’t want to arrive somewhere sweaty or are simply worn out near the end of a long ride or perhaps carrying an injury.
Torque Sensing Pedal Assist
Various systems are used to sense when the pedals are turning, or, in more sophisticated designs, how hard the rider is pressing on the pedals – so-called torque sensing.
This information is translated into electrical energy to power the motor and assist the rider. The best designs, such as the mid-drive systems from Bosch, Brose, Shimano, and Yamaha, produce an instant electrical surge that exactly matches your push on the pedals, giving the strange and rather magical feeling of having bionic legs.
Having said that newer, more budget-priced mid-drives with torque-sensing are coming onto the market and we’re impressed with the Shengyi torque-sensing motor on the MOD Berlin.
Torque sensing is primarily associated with mid-drives but hub motor systems can also benefit from it too, a good example being the Tenways CGO600 single speed, as pictured above.
The torque sensor itself may be located in the bottom bracket pedal axle area or more rarely somewhere around the rear axle as in the picture above.
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