The picks on the specs that matter here
Sensor type is not something Amazon listings reliably publish, so each cell below is quoted from the source we already hold for that bike — the maker’s own page or the independent test we cite for it. Jasion states nothing about the EB5’s sensor, so that cell says so rather than guessing.
Torque sensor versus cadence sensor: the whole argument
Almost every e-bike under $1,000 uses a cadence sensor. It detects that the pedals are turning and switches the motor to whatever assist level you selected. It does not care whether you are pushing hard or spinning your feet in circles, which is why cheap e-bikes feel like a switch: you turn the cranks, the bike surges, and you can coast along contributing almost nothing while the display says you are pedaling.
A torque sensor measures how hard you are actually pushing and scales the motor to match. Pedal gently and you get gentle help; stand on it and you get everything. For exercise that distinction is the entire ballgame, because it makes effort the thing that controls the bike. It also feels far more like a bicycle, which is why torque-sensing bikes are usually the ones people keep riding.
Two of our four publish a torque sensor: the GoTrax F3 (per the independent test we cite for it) and the Heybike Mars 3.0 (per Heybike’s own page). Retrospec publishes a cadence sensor with five assist levels for the Beaumont Rev. Jasion publishes nothing about the EB5’s sensor, and at that price it is safe to expect cadence. Our pedal-assist guide goes deeper into how the two systems behave on the road.
Gears matter more than watts
Here is the mistake people make: they buy the most powerful bike they can afford, turn the assist down to level one to “get a workout,” and discover they are grinding a 65 lb bike in the wrong gear at 40 rpm. That is not aerobic exercise, that is a leg press.
What you want is enough gearing to hold a comfortable cadence — roughly 70 to 90 rpm — at whatever speed and gradient you are riding, with the assist low or off. All four picks here have a Shimano 7-speed, and the Chatham Rev’s Mega-Range version has the lowest bail-out gear in our registry. That is the spec that lets you ride a hill under your own power instead of reaching for the throttle, and it is the reason a 350 W geared bike with seven cogs is a better exercise bike than a 750 W single-speed.
Weight is the hidden tax
With the motor on, an e-bike’s weight barely registers. With the motor off or on its lowest setting, every pound is yours. The spread in our registry is large: the Jasion EB5 is 49.6 lb, the Retrospec Beaumont 57.5 lb and the GoTrax F3 58.3 lb, while the fat-tire folders run from the high sixties into the seventies — and Heybike publishes no weight at all for the Mars 3.0, though independent testing of it recorded 71.7 lb.
A 50 lb bike with the assist off is a heavy bicycle. A 72 lb bike with the assist off is an argument you will lose. If part of your plan is riding unassisted some of the time — and it is the single best way to make an e-bike into exercise — weight should outrank battery capacity in your decision. That is also why the lightest pick here is also the cheapest, which almost never happens in this category. Our weight guide has the full picture.
How to actually get fitter on one of these
The useful framing is not “does an e-bike count” but “how much riding will I do, and at what intensity.” The CDC guideline is 150 minutes a week of moderate-intensity activity, and the e-cycling review puts assisted riding at or above that threshold. Three commutes a week of 25 minutes each clears it, which is the real argument for the e-bike over the bike you would have left in the garage.
Four habits do most of the work. Ride assist level one as your default and keep the higher levels for headwinds and hills, rather than the other way round. Turn the assist off entirelyon the flat section of your regular route and let it back on when the ground goes up — that is interval training without calling it that. Ignore the throttle, or buy a bike whose throttle you can disable: a Class 1 setting makes the decision for you. Make it the transport, not the workout— the research finding that matters most is that assisted bikes get used more often, and frequency beats intensity for almost everyone reading this.
For the calorie arithmetic and the comparisons against running, walking and the gym, our cycling for weight loss guide and e-bike versus regular bike do that properly, with sources. This page is about which bike to buy.
What about just buying a regular bike?
Honestly: if you are already riding a bicycle regularly and enjoying it, an e-bike is a lateral move for fitness and you should spend the money on something else. The case for the e-bike is specific. It is for the person whose commute has a hill that ends the idea before it starts, the person coming back from injury or illness who needs the option of help on the way home, the rider who is 40 lb heavier than they want to be and finds an unassisted bike genuinely unpleasant, and the person whose riding partner is much fitter than they are.
In all four of those cases the alternative is not a regular bike. It is no bike. That is the comparison that matters, and it is the one the research on assisted cycling keeps landing on: moderate-intensity activity, done more often, by people who were not previously active.
What we would actually buy
For most people: the GoTrax F3. A torque sensor, a 672 Wh pack that removes range anxiety as a reason to use more assist, 58.3 lb, a 7-speed, and a selectable class so you can run it as a Class 1 pedal-assist bike with no throttle. Skinnier tires than the fat-tire crowd, which is the right choice for road miles.
On the tightest budget: the Jasion EB5. At 49.6 lb it is the lightest e-bike in our registry, the 350 W motor is modest enough that your legs stay relevant, and the 7-speed and front fork make it a usable bicycle when the battery is flat. Jasion publishes no class and nothing about the sensor, which we would hold against it on any other page.
Starting from genuinely unfit, or nervous: the Retrospec Beaumont Rev. A 19.35-inch standover means you step through rather than swing a leg over, it is 57.5 lb, and both the bike and the battery carry UL listings. It is a cadence-sensor bike with five assist levels, so discipline is on you — but the bike you are not intimidated by is the bike you ride.
And past $1,000, if comfort is what is stopping you: the Heybike Mars 3.0, for a torque sensor plus full suspension plus both UL listings. It is the heaviest option here and Heybike will not publish the weight, the top speed or the class, which is why it is fourth rather than first.
