“My cycle computer isn’t working.” That was a common phrase uttered by customers when I used to work at a bike shop. More often than not, it was something simple – like a dead battery. Other times, it was something just as simple but harder to see. We’ve all experienced it. If the magnet isn’t in the perfect location for the pick up on the sensor, your computer reads a big fat zero.

How to fix it? Simple. Get rid of the magnet all together…

Obviously, PowerTap is not the first company to go magnetless for their speed or cadence sensors, but the addition of their newest device makes for yet another option for consumers. Equipped with dual band Bluetooth Smart and ANT+ compatibility, the device is meant to pair with other electronics whether GPS units, smartphones, etc. and measures the rotation of the sensor with an accelerometer rather than relying on the rotation of a magnet. That should mean the days of knocking your sensor out of alignment are a thing of the past.

Able to be mounted to your hub shell for speed, or your crank arm for cadence, the sensor is designed to do one at a time. Once programmed for speed or cadence, the sensor has a light that indicates its function – white for speed, and green for cadence.

Inside is a coin cell CR2032 battery which is said to provide 200 hours of battery life, and the sensor will go to sleep in 5 minutes if there is no movement to save on battery. PowerTap claims the device has a +/- 2% accuracy, and is IPX7 water resistant. Sold for $49.99, the sensor includes a rubber foot print and rubber bands to attach it to your crank or hub.



  1. I’m a little surprised that in 2017 there is a market for a speed/cadence sensor, given the proliferation of GPS-enabled computers. Still, if you want cadence info and don’t have a crank-based power meter that provides it, I suppose this would do the trick.

    • You will find your speed display bounces around a lot less if you have a speed sensor. With GPS only you can watch your speed change while you are standing still.

    • Speed + GPS is far more accurate than just GPS. The computer can use the Kalman algorithm to produce more accuracte results than the speed or GPS alone. Also there are many times when the GPS data is just unavailable like bad satellite constellation, mountainous region, or tree coverage.

    • GPS units are no where near accurate recording speed and distance, especially on a mountain bike. I’m still using old wired cyclocomputers until I see a good solution for this.

      This is the kind of thing that might have me move to a more modern bike computer. However, just 200 hours on a charge SEEMS rather limited seeing as I get 2-4 years of battery life out of my current set-up. That won’t last a full riding season on my road bike, but would probably be just an annual battery replacement for my MTB.

      • Mountain biker to mountain biker that is just not true! What modern computers have you even tried to come up with that statement? Wired computers can be wildly inaccurate!

  2. This design looks like a pain to mount on a hub, especially if you have a decent number of spokes for touring. I find even Garmin’s speed sensor with its one piece rubber holder/band tough to get on when you have to reach between 40-48 spokes.

    Magnetless is definitely the way to go, fewer things on the bike is always better.

    • I agree, it is hard enough to get the Garmin version with a single mount point onto the hub with certain wheels, let alone this dual band setup. It also looks pretty big in comparison to the Garmin items. Seems like a design fail.

  3. I have to use a speed sensor on my Wahoo Element in the woods. I was getting 12-13% less than my group average distance readings. For road, I don’t worry about it as the only time you’ll see some drops is going under bridges and the occasional tree.

  4. If the magnet sensor had just been invented, then it would be the best innovation since clipless pedals. You don’t need to be a rocket scientist to get them to work and they don’t require a landfill filling battery.

    • “they don’t require a landfill filling battery.”

      Yes, even the magnet based speed and cadence sensors require batteries. Where do you think the power to transmit the signal from the magnet passover count goes?

      The battery provides the power, while the magnet simply trips the counter each time it passes the sensor.

  5. Nice that this one device can be switched between speed and cadence. I don’t think you can do that with Wahoo or Garmin’s magnetless sensors.

    • It is nice to reprogram them, but I thought Garmin’s we’re $70 for both. I’m also confused how there aren’t a variety of third party offerings by now, Garmin’s design has been used for several years now.

  6. I am still running my >10 year old Polar CS600X with W.I.N.D. sensors and the newer H3 heart rate sensor. No gaps, absolutely precise. 🙂 The sensors batteries can only be changed by cutting the sensors open, though. Or you pay 50 bucks for a new one (luckily they will last some years)… 🙂 My mates GPS units always have problems. I will only switch, if the head unit breaks down one day. 🙂

  7. I have an advanced copy of this sensor and it works really well. I am using it as a speed sensor but will get a second for cadence. I have it paired with a Garmin 820 and will use with zwift this winter.

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