Like a gas pedal →
Press harder. Go faster.
The motor measures how much force your legs put into the pedals and matches it. A gentle spin gives a gentle boost. Muscle into a hill and the motor surges with you. You feel like you have superhuman legs.
Kepler Sensor System
Torque or cadence.
Switch mid-ride.
Most e-bikes lock you into one pedal sensor for life. The Ariel Rider Kepler ships with both, and lets you switch from the display in three taps.
Torque Sensor
Push harder. Get more power.
The motor mirrors your effort. Natural, responsive, efficient.
Cadence Sensor
Just pedal. Let it cruise.
Steady help at every pedal stroke. Effortless.
4.8 / 5 rider rating
1,400+ verified reviews
1-year warranty
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Two sensors. One switch. Zero tools.
Try it yourself
Feel the difference in 10 seconds
Drag your pedaling effort. Watch torque scale with your legs while cadence holds a flat line. This is the whole story of the Kepler sensor system, on one screen.
Cadence PAS level 3
Push harder, the motor gives more. Ease off, it backs down. Your legs set the pace.
The simplest way to think about it
It works like the pedals in your car
You already know the difference. One responds to how hard you push. The other stays at a set level until you change it.
Like cruise control →
Set a level. Stay there.
The motor only cares whether the pedals are turning. Pick an assist level 1 to 5 on the display and it holds steady, no matter how hard you actually push. Predictable, smooth, easy on the legs and knees.
Inside the sensors
Two real sensors. Not a software trick.
A tiny gauge that feels how hard you push
A strain gauge bonded to the drivetrain flexes microscopically every time you pedal. The amount it bends is proportional to the force your legs apply. A chip reads that signal hundreds of times per second and tells the motor controller exactly how much assist to deliver. That's why torque mode feels so natural, the motor is always matching your actual effort.
- Measures
- Pedaling force (Nm)
- Samples
- 100+ per second
- Feels like
- Your legs, amplified
A ring of magnets that counts your pedal strokes
A ring of small magnets rotates with the pedal crank. A tiny Hall-effect sensor counts how many magnets pass by per second. As long as the pedals are turning, the motor applies the PAS level you selected, level 1 is light, level 5 is maximum. Stop pedaling and the motor cuts off.
- Measures
- Pedal rotation (yes/no)
- Levels
- 5 fixed assist steps
- Feels like
- Cruise control for legs
Side by side
Torque vs cadence at a glance
Quick reference. The highlighted winner is the one most riders prefer for that scenario.
| Feature | Torque | Cadence | Kepler |
|---|---|---|---|
| What it measures | How hard you push | That you're pedaling | Both, switchable |
| Ride feel | Natural, responsive | Smooth, predictable | You choose |
| Best for hills | Scales with effort | Fixed, can feel weak | Switch to torque |
| Best for flat commutes | Works, more effort | Set and forget | Switch to cadence |
| Battery efficiency | Usually more range | Uses your set level | Pick per ride |
| Learning curve | Natural in minutes | Zero, like a throttle | Easy either way |
| Easy on the knees | You control intensity | Reliable at low PAS | Both |
| Switch from the display | ✕ | ✕ | ✓ Mid-ride |
When to use each
The right mode for the moment
Quick cheat sheet. Switch anytime, even mid-ride.
Climb without strain
The motor matches your effort. Push hard on a climb, the motor pushes with you. Efficient power, right when you need it most.
Cruise without thinking
Steady assist at every pedal stroke. Set your PAS level on the display and roll. Predictable speed, minimal effort, perfect for stop-and-go traffic.
Stretch the battery
Torque mode only draws power proportional to your effort. Light pedaling = light assist = more miles. Go easy and watch the range climb.
2
Sensors included
3
Taps to switch
110
Nm of torque
105
Max range (mi)
Kepler Dual Battery
Kepler Dual Battery
What riders say
Riders who made the switch
★★★★★
I started on cadence because I was new to e-bikes. After a month I tried torque and it felt like a totally different bike, more natural, more responsive. Having both is like owning two bikes.
★★★★★
My knees can't take a lot anymore, so I ride cadence at PAS 2 on the flat part of my commute. When I hit the bridge I flip to torque and let my legs pull their share. Nobody else offers this.
★★★★★
Had a Lectric before. Cadence only. The Kepler in torque mode climbs like a dirt bike. I switch to cadence when my kid is on the back seat for the smooth takeoff. Sold.
Both sensors. All Kepler models.
Torque and cadence come standard on every Kepler. Switch from the display. Ride your way.
Questions
Sensor switch, answered
I have never ridden an e-bike. What is a pedal sensor?
A pedal sensor is the part that tells the motor when to help you. Every e-bike needs one. There are two common types: torque (reads how hard you push) and cadence (reads that you're pedaling). The Kepler has both.
What is the difference between torque and cadence sensors?
A torque sensor measures how hard you push the pedals and scales motor assist proportionally. A cadence sensor detects that you're pedaling and applies a fixed assist level you chose on the display. Torque = sport mode (responsive). Cadence = cruise control (consistent).
Can I really switch sensors while riding?
Yes. Hold the menu button on the display for 2 seconds, pick Sensor Mode, choose Torque or Cadence, done. The change takes effect on the next pedal stroke. No tools, no stopping, no dealer visit.
Which mode is better for hills?
Torque mode is better for hills. It responds to your pedaling force, push harder on a climb and the motor delivers more assist. Cadence applies the same assist regardless of effort, which can feel weak on steep grades.
Which mode is better for commuting?
Cadence mode is better for commuting. It provides steady, predictable assist at each PAS level. Set it, cruise, don't think. Ideal for flat terrain and stop-and-go traffic.
Which mode gives better range?
Torque is usually more efficient, the motor only delivers power proportional to your effort. Light pedaling uses minimal battery.
Do other e-bikes let you switch sensors?
Very few e-bikes let you switch sensors. Aventon uses torque only. Lectric and Rad Power use cadence only. Most brands pick one and lock you in. The Kepler is one of the only e-bikes under $2,500 that ships with both sensors and lets you switch from the display. Fine-tune each mode's PAS curves from the Ariel Rider app.
The pedal assist feels jerky. What should I do?
Switch to torque mode. Cadence at higher PAS levels can feel aggressive on the first pedal stroke. Torque ramps power proportionally to your effort, eliminating the on/off surge.
Are both sensors physically installed, or is one just software?
Both are real hardware built into the Kepler's drivetrain. A strain gauge for torque, and a magnetic ring with Hall-effect sensor for cadence. Switching changes which sensor the controller reads, it's not a simulation.
What's a PAS level?
PAS stands for Pedal Assist System. It's the assist level you choose on the display, from 0 (motor off) to 5 (maximum assist). In cadence mode, PAS sets how much power the motor applies. In torque mode, PAS sets how much the motor multiplies your effort.
How does this affect warranty or service?
The switchable sensors do not affect warranty or service. Both sensors are stock hardware, covered by the full 1-year Ariel Rider warranty. Switching modes from the display is a standard feature, not a mod.
Can I return the bike if I don't like it?
Yes. Ariel Rider offers a return window so you can test-ride at home. See our return policy for the current terms.