Speed Centric vs. Torque Centric Electric Bikes
If you're shopping around for an ebike you've likely come across these phrases. To clear the air and give you better information so you can get the bike that is best fit for you, we shall discuss and simplify the differences between a speed-centric and a torque-centric pedal assist system.
To aid us in the discussion, we are going to use two ebikes; the Sondors Fold X and the Priority Current. The Priority Current is a mid-drive ebike while the Sondors Fold X is a rear hub driven ebike. More importantly, the Sondors Fold X is a speed-centric ebike while the Priority Current is torque-centric. We will go over their differences and what the feel and ride is on these different pedal assist configurations.
Speed-centric pedal assist like on the Sondors Fold X relies on sensors to measure and track the movement of the pedals. It has a series of magnets on the crank arm and sensors that are fixed onto the hub. When the sensor detects that there is movement, it will signal for the motor to give power to the rear wheel. The level of pedal assist can be configured on the ebike’s interface. On a speed-centric ebike, it gives instantaneous and constant power. As long as you are pedaling and moving, the motor will keep on providing pedal assist. On the Sondors Fold X, you will see a little red light which will light up as you start to pedal and the motor will kick in to give power to the rear wheel.
The best thing about this type of pedal assist is that it is very easy to service. The parts are small and are relatively inexpensive. If they need servicing or replacement, it is easy to just remove the whole crank set off and slide the new part in. However, since this pedal assist is very basic, it doesn’t give you extra assistance when you’re riding over an uphill terrain. Instead, as previously mentioned, it will just give you constant power while you’re pedaling.
On the other hand, a Torque-Centric pedal assist will give you power based on how much power or torque you are putting onto the cranks. This can be seen on the Priority Current ebike and other higher quality electric bikes on the market. If you’re in a low gear or just cruising and pedaling lightly, it will also give a low pedal assist. However, once you are on a hill and you’re exerting more force into pedaling, the bike will sense and account for this, and deliver more power accordingly. Inside the hub of a torque-centric ebike is a power meter built into the spindle that tracks how much power is being exerted by the rider on the crank arms. It continually measures and analyzes the situation a rider is in. It is more complex and adaptive rather than just giving consistent power output. In our opinion, torque centric feels more natural.
Typically, torque-centric ebikes will usually not have throttles on them (there may be some that have, but generally they are pedal assist only). Because of this, torque-centric ebikes are more into the fitness style.
However, one of the downsides of a torque-centric pedal assist is its repairability. If something goes wrong with the unit, the whole thing needs to be replaced. There are not a lot of options of taking it apart and repairing or replacing individual parts. And consequently, replacing the whole unit can get very costly, especially compared to the inexpensive pedal assist sensor on a speed-centric configuration. Additionally, from a resting position, a torque-centric ebike doesn’t get going as quick and jumpy as a speed-centric one where it gives you constant power the instant you start pedaling.
Which is better?
Both pedal assist configurations have pros and cons. And ultimately, the best one is the kind that will fit your needs and wants. If you're looking for more of a fun, cheap, slightly delayed pedal assist to go fast, maybe the speed sensor is better for you. However, if you're looking to get more response out of your ride, just get a little bit of assistance, and feel like you’re riding a traditional bicycle rather than feel like a motor is propelling you, then maybe a torque-centric ebike is best for you.