Throttle or pedal assist? It's one of the most personal decisions in e-bike setup. Here's how to choose based on your riding style and goals.
Every e-bike conversion kit offers one or both of two power delivery modes: throttle (twist or thumb lever, like a motorcycle) and pedal assist (motor kicks in when you pedal). Most BAFANG and Tongsheng kits include both, but you'll quickly find that you use one much more than the other.
This guide covers how each mode works, the pros and cons, the legal implications, and which mode fits different riding styles. By the end, you'll know which mode to prioritize and how to configure your kit.
How Throttle Mode Works →
How Pedal Assist Mode Works →
Pros and Cons: Throttle →
Pros and Cons: Pedal Assist →
Which Should You Use? →
How Throttle Mode Works
A throttle is a twist grip (like a motorcycle) or thumb lever that delivers motor power on demand, with no pedaling required. Most kits use a thumb throttle on the right side of the handlebar — twist throttles are less common in conversion kits because they replace your grip.
When you press the throttle, the controller sends power to the motor proportional to how far you've pressed. Half throttle = half power. Full throttle = maximum power (limited by your assist level setting on most kits).
Throttle mode is binary in the sense that the motor responds to your throttle input, not your pedaling. You can pedal while using the throttle (combined mode) or just use the throttle alone (scooter mode). Most US e-bike riders use combined mode for efficiency — the motor does 50-70% of the work via throttle, and they pedal for the remaining 30-50%.
A 750W kit with throttle can reach 20mph without any pedaling — the federal legal limit for throttle-only e-bikes. Above 20mph on throttle, you're legally in moped territory in many states.
How Pedal Assist Mode Works
Pedal assist (PAS) delivers motor power automatically when you pedal, based on your chosen assist level. There's no throttle input — the motor senses your pedaling via a cadence sensor or torque sensor and adds power accordingly.
Most kits offer 3-9 assist levels. Level 1 (eco) adds maybe 30% to your pedaling effort. Level 5 (sport) might add 200%. Level 9 (turbo) adds 300%+. You shift between levels using up/down buttons on your display.
PAS is more efficient than throttle — you're contributing to the work, so the motor doesn't have to do it all. A 750W motor in level 3 PAS consumes about half the Wh per mile of the same motor at full throttle.
Federal law allows PAS to assist up to 28mph (Class 3 e-bike), vs 20mph for throttle-only (Class 2). This is why PAS-equipped e-bikes have higher legal top speeds than throttle-only e-bikes in most jurisdictions.
Pros and Cons: Throttle
Pros of throttle mode:
- Instant power on demand — great for getting through intersections quickly
- No pedaling required — useful when you're tired, injured, or dressed for work
- Easy low-speed control — useful in technical terrain or tight spaces
- Works from a dead stop — PAS usually requires you to pedal a half-revolution before kicking in
- Familiar feel for motorcycle/scooter riders
Cons of throttle mode:
- Higher battery consumption (30-50% more Wh per mile than PAS)
- Less exercise — easy to get lazy and just use the throttle
- Harder to modulate at low speeds (especially with cadence-sensor motors)
- Legal restrictions — throttle-only limited to 20mph in most US states
- Can surprise you if you bump it accidentally — always turn off the throttle when stopped
Pros and Cons: Pedal Assist
Pros of pedal assist:
- More efficient — extends range 30-50% vs throttle
- Better exercise — you're still pedaling
- Higher legal top speed (28mph Class 3 vs 20mph Class 2)
- Smoother power delivery (especially with torque sensors)
- More natural cycling feel
- Better for group rides with non-electric bikes
Cons of pedal assist:
- Requires pedaling — not ideal when tired, injured, or in work clothes
- Half-revolution lag on cadence sensors before power kicks in
- Less precise low-speed control
- Some riders find it harder to start on hills (need to pedal before power arrives)
- Harder to ride with a passenger (throttle is more reliable for getting started)
Which Should You Use?
For most riders, the answer is 'both, depending on the situation.' Here are our recommendations:
Commuters in hilly areas: PAS for the commute, throttle for the final block when you're tired and don't want to show up sweaty. Configure your kit's throttle to be limited to level 3 (out of 9) — enough to get you home but not enough to drain your battery.
Commuters in flat areas: PAS only. You'll get plenty of exercise, maximize range, and the throttle just adds weight and complexity.
Recreational riders: PAS for exercise, throttle for when you're tired. The beauty of e-bikes is that you can choose how much work to do on any given ride.
Cargo bikers: Both, but rely more on throttle. Getting a loaded cargo bike moving from a dead stop is much easier with throttle — you don't have to fight the weight while waiting for PAS to engage.
Seniors: PAS for exercise, throttle for hills and headwinds. The combination gives you the cardiovascular benefits of cycling with a safety net for tough moments.
MTB/off-road riders: PAS for climbs (more control), throttle for technical sections where you can't pedal. Most MTB riders end up using throttle sparingly, mostly as a 'get me un-stuck' button.
Legal considerations: If your state restricts throttle-only to 20mph (most do), configure your kit to obey that limit on throttle. PAS can usually go to 28mph legally. Setting these limits correctly in firmware keeps you legal and insurable.