The Tongsheng Torque Sensor: How It Actually Works
The torque sensor is Tongsheng's central technical argument — and the point most product listings explain worst. Here's what it actually measures, and why it changes how the bike responds to your pedaling.
What a torque sensor measures
A torque sensor, built into the bottom bracket axle, measures the actual force applied to the pedals, continuously. The harder you press, the more the electric assist increases, in a proportion calibrated by the controller. The motor doesn't just react to the fact that you're pedaling: it reacts to the intensity of your pedaling, moment by moment.
Across the entire Tongsheng range we track (TSDZ2, TSDZ2B, TSDZ8, TSDZ16), this sensor comes standard — Tongsheng's official spec sheets document it consistently ("Torque Sensor" or "Speed/Torque" depending on the model).
Torque sensor versus cadence sensor
The most common alternative among competitors is the cadence sensor, which simply detects that the pedals are turning and applies a fixed assist level for the selected mode — regardless of the force applied. That's the case with the Bafang BBS02B and BBSHD, the best-selling conversion kits after Tongsheng's.
What this means in practice. With a torque sensor, pressing harder on the pedals increases assist immediately and proportionally — the feel is that of a strengthened bike, not a motorized one. With a cadence sensor, assist stays the same until the mode is changed manually: pedaling harder doesn't speed up the motor's help.
→ The full Tongsheng vs Bafang comparison
Speed + torque: the nuance in recent models
The official spec sheets for the TSDZ8 and TSDZ2B specify a "Speed + Torque" sensor, not "Torque" alone. That means the controller combines two pieces of information — force applied (torque) and pedal rotation speed — for a finer assist calculation, particularly at startup and through changes in cadence.
The original TSDZ2, older, is generally described as a "torque + cadence" sensor by resellers and the open firmware community — a similar architecture in principle, but less officially documented.
The battery-saving argument
Several product listings claim a torque sensor can save up to 30% battery compared to a cadence sensor, since assist only delivers the power actually needed for the effort applied. The physical principle makes this plausible — a cadence sensor often delivers more power than strictly necessary to maintain a fixed assist level — but we found no independent measurement quantifying this gain precisely for Tongsheng motors.
What this means for your motor choice
Sensor type doesn't differentiate Tongsheng models from each other — all four have one. It's more a brand-level argument than a model-level one: if a natural pedaling feel versus cadence-sensing kits is your priority, any Tongsheng motor in our selection meets that criterion.
→ Which Tongsheng motor to choose for your use case · Our full ranking
Frequently asked questions
Does a torque sensor use less battery?
Several resellers claim it does (up to 30% savings per one Amazon listing), since assist follows actual effort rather than a fixed level. We found no independent measurement confirming that precise figure, but the underlying principle (proportional rather than binary assist) makes some savings plausible.
Do all Tongsheng motors have a torque sensor?
Yes, it’s a constant across the entire TSDZ range (TSDZ2, TSDZ2B, TSDZ8, TSDZ16). It’s even the brand’s central argument against competitors like Bafang, whose best-selling models (BBS02B, BBSHD) use a cadence sensor.
Can you adjust the torque sensor’s sensitivity?
On the original TSDZ2, yes, very finely, via the TSDZ2-Smart-EBike open-source firmware project. On more recent models (TSDZ2B, TSDZ8, TSDZ16), adjustments go through the display and stock controller, with less room for customization.
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Tongsheng TSDZ2
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