Speed, cadence and heart rate sensors
A sensor is a five-year purchase attached to a two-year head unit. The specification that decides whether it survives the change is not accuracy — they are all magnet-free and all accurate enough — it is which protocols it broadcasts on.
Dual protocol, an IP rating, and the mount.
Dual protocol because it decides compatibility with the computer you have not bought yet. An IP rating because a sensor lives at hub or crank height, which is where road spray goes. And the mount because a sensor that comes loose stops reporting without saying so.
1. Garmin Speed Sensor 2 and Cadence Sensor 2 bundle. Both sensors, ANT+ and Bluetooth 5.0, and one capability nothing else here has: the speed sensor records on board. A commute logged with no head unit on the bars at all, then synced afterwards, is genuinely useful and it is not a feature its competitors offer. The speed sensor mounts on the hub, so there is nothing hanging off a spoke.
2. CooSpo BK467. Speed and cadence, ANT+ and Bluetooth, and an IP67 rating — the only stated ingress figure in this list. IP67 means dust-tight and survives immersion, which is more than a bike sensor should ever need and exactly what it will get in a February downpour.
3. Magene S3+. Dual mode, ANT+ and Bluetooth 4.0, magnet-free, at the lowest price here and the best-selling sensor on this site. Two of them cover speed and cadence for less than one conventional pair. Magene also publishes the fact that two versions of the S3+ circulate with different battery compartments — unusually honest, and worth knowing before you buy a second one a year later.
Crank clearance for a cadence sensor: it sits on the inside face of the crank arm and has to clear the chainstay through a full rotation. Measure with the crank at its closest point, not at the bottom of the stroke.
Where a sensor is what lets a normal bike and a dumb trainer feed data into an app.
Where GPS is unreliable: forests, cities, tunnels. A wheel sensor measures rather than estimates.
The number that changes how people ride, and one that only a sensor provides.
Where a sensor per bike and a single head unit is a common and cheap arrangement.
| Your need | The sensor | Why |
|---|---|---|
| Indoor training | Speed and cadence | The app needs data |
| Riding under cover | Speed | GPS drops out |
| Pedalling technique | Cadence | GPS cannot infer it |
| Open road with GPS | Possibly neither | GPS is adequate |
These sensors are sealed and simple, and almost every fault is the battery or the mount. A sensor that drops out intermittently has a low coin cell or a rubber strap that has stretched, and neither is a failure of the sensor itself.
Small components near moving parts.
Both sensors · ANT+ and Bluetooth 5.0 · on-board storage · hub mount
A bundle of both sensors, storing distance on board so rides record without a head unit present, over ANT+ and Bluetooth 5.0.
Best for: Garmin users who want both measurements, and anyone who wants rides logged without carrying a computer.
≈ $125
Speed/cadence · Bluetooth and ANT+ · IP67 · app compatible
A dual-protocol speed and cadence sensor with a published IP67 rating and stated compatibility with Zwift, Rouvy, Ride with GPS, Peloton and Wahoo apps.
Best for: Indoor training, where named app compatibility and a sealed housing both earn their place.
Dual mode speed/cadence · ANT+ and Bluetooth 4.0 · magnet-free
The best-selling sensor in this hub: one unit that switches between speed and cadence mode by reseating the battery, broadcasting on both ANT+ and Bluetooth.
Best for: A first sensor, or a pair of them, at the price of a set of brake pads.
≈ $17
ANT+ is the protocol most dedicated bike computers expect and it lets several devices listen to one sensor at once. Bluetooth is what phones and watches use, and a Bluetooth connection is usually exclusive to one device. A sensor broadcasting both works with either, which is why every sensor in this list does.
They need a wheel circumference to convert rotations into speed, and most head units either ask for it or take it from the GPS over the first few rides. Cadence needs nothing. There is no magnet to align, which is the failure that used to end most sensor installations.
Not at the same time. The Magene S3+ switches between the two modes, so a pair covers both roles — which is what makes buying two of them cheaper than buying a dedicated pair.
On open roads, usually not. Under tree cover, in cities and indoors, a wheel sensor measures where GPS only estimates or fails.
Your pedalling rate, which GPS cannot infer. It is the number most likely to change how you actually ride.
Only if they speak the same wireless protocol. Dual-protocol sensors work with almost everything and cost little more.
Almost always the wheel circumference setting. A speed sensor converts rotations into distance and needs the right number to do it.
Usually a low battery or a loose mount rather than a fault. Replace the coin cell and check the strap before assuming the worst.
Magnetless sensors are simpler to fit and have nothing to align. Magnet types are cheaper and work fine when the magnet stays put.
For the rider who: Garmin users who want both measurements, and anyone who wants rides logged without carrying a computer.
Biggest plus: Both sensors in one purchase, so no second order and no mode-switching
Biggest minus: Roughly four times the price of a single dual-mode sensor here
For the rider who: Indoor training, where named app compatibility and a sealed housing both earn their place.
Biggest plus: A published IP67 rating, which neither of the cheaper sensors here states
Biggest minus: Rank 18,341, so much less bought than the Magene at the same price
For the rider who: A first sensor, or a pair of them, at the price of a set of brake pads.
Biggest plus: Rank 1,025 — the best-selling sensor here, at the lowest price
Biggest minus: Switching mode means reseating the battery rather than pressing a button
Spares and fitting kit from the same aisle, at the price we read. Confirm they match the bike and the part you chose before ordering: it turns on the standard and the part number, which the listing gives.
Direct match-ups already published between two picks from this guide or this aisle.
Everything listed is drawn from the catalog of this site. Specifications are the published ones, from the maker and from Amazon; prices are what Keepa recorded on the date shown, and both move. The order rests on declared specifications, on stated strengths against stated limits, and on price. None of this kit has been ridden by us, and the page makes no such claim.
Last checked on
Prices quoted in these summaries are dated readings. The live price is shown next to each product.
Bike racks, trainers and computers swing by thirty dollars or more across the year, and the biggest "discounts" often land at prices the same model sold for six weeks earlier. UniverTrack tracks the real price history across retailers, spots fake reductions, and alerts you when it is genuinely the moment to buy.
