PowerTap Magnetless Speed or Cadence Sensor Review

PowerTap’s Speed and Cadence sensor, looking nice and shiny attached to my significantly less nice and shiny crank arm

Speed and cadence sensors have been available for mountain bikes for quite some time now, and plenty of riders have added them to their rigs to help them keep tabs on just how fast the spinny bits are spinning. As with any crowded market segment, companies looking to take a piece of the cyclocomputing pie have to offer something special to catch the eye of the data-obsessed cyclists of the world. PowerTap hopes that they have just that special something with their Magnetless Speed/Cadence sensor. Read on to see if this is just what you need to fill your training plots with even more useful data.

Orienting and Creating Data

Most speed/cadence sensors have relied on the use of a magnet, a Hall effect sensor, and some sort of wiring to connect the sensor to power and a cycling computer. Thankfully, PowerTap has opted to remove the wires and magnets completely and have pared everything down to a device smaller than a pack of gum. The Magnetless Speed/Cadence sensor is one of those products that impresses with its simplicity and compactness; it ships in a tiny box, has no extra accessories aside from differently-sized mounting straps, offers no frills and no extra fluff. As its name implies, it’s a speed sensor and a cadence sensor; in our golden age of bells and whistles, it’s pretty refreshing to find a product that only does exactly what its name implies and nothing else.

It’s worth noting that PowerTap officially calls its device a “Speed or Cadence Sensor.” That little operator between speed and cadence belies the sensor’s functionality; the sensor serves two functions, based on its orientation. When placed on the crank arm of your bike, you’ll be gathering cadence data derived from the sensor’s rotation. When placed on the hub of your wheel, the sensor will be sending speed data, based on the rotation of your bike’s wheel.

At this point, you might find yourself asking, “how does this fancy little piece of electrical wizardry know how to work?” The answer lies in a clever little trick that PowerTap devised. The PowerTap sensor uses accelerometers, small devices that create a voltage signal based on their position and motion, which is then turned into useful data by a computer that decodes the voltage signal into numbers that humans like us can make sense of. Based on the sensor’s orientation when you turn it on, it will set itself to read cadence or speed.

“Ok, I already understood how accelerometers interpret motion and translate it into electrical signals,” you may find yourself saying, “but there’s no power switch. How do I turn it on?” this is another clever trick that PowerTap integrated into their sensor. It will automatically power on as soon as it senses motion and will power down after a preset time without motion.

Syncing up the Speed and Cadence sensor to my Suunto Ambit 3 couldn’t have been easier. Now I know all about how fast my legs are spinning and how much power is being made when I’m out dropping watt bombs at the races.

This simplicity of operation is present when pairing the sensor with your computer or watch; the sensor uses the Bluetooth ANT+ standard and is easily recognized by most all devices (including your phone, if you’ve not decided to buy into the world of cycling computers) and will pair just about instantly. Just set your device to search for sensors/pods, give your crank or wheel a spin, and the sensor will start beaming data to your device automagically.

With such an easy setup, it should come as no surprise that the actual operation of the sensor was simple as well. Once connected, my watch, the Suunto Ambit3, discovered the sensor every ride, and I was able to see my cadence or speed in real time. The real benefit of monitoring your cadence isn’t necessarily in the moment, but more in the post-ride analysis. As of this sentence, we’re already 600 words deep in this article, so I’ll save the heady data analysis discussion for another article.

Regardless of conditions, whether riding in the arid eastern half or the rainforest-filled western half of my home state of Washington, the sensor performed flawlessly.

Why Should I Strap One on to My Bike?

It’s easy enough to determine why you want to keep tabs on your speed–how else would you be able to brag to your friends about how much faster you are? But the reasons behind monitoring cadence are a bit more abstract. I suppose you could boast about how fast you can spin your legs, but the real value is using that data to make decisions on how well you’re performing versus how well you could be performing.

A higher cadence means a more efficient use of your slow-twitch leg muscles, which are the quick-recovering, fat-burning best friends of all cyclists. Though there isn’t one “golden cadence” for all cyclists to follow, multiple studies point to spinning a cadence in the 80-90rpm range as being close to ideal.

After uploading my ride to Strava, I now have conclusive evidence that I’m both slow and a bit of a lightweight in the power department. But hey, sometimes data can be a cruel, unforgiving mistress.

If you’re training to improve your endurance, using your cadence as a guide is a vital step in creating an effective exercise routine. By spinning intervals at set cadences and following a structured workout schedule, you can quickly develop your leg muscles’ strength and decrease their recovery time, making your time checked in to the wattage cottage that much more potent. A little bit of diligence and data can go a long way in making you a contender for the podium or just letting you tackle more miles out on the trails.

The Final Word

Overall, I’m completely satisfied with PowerTap’s Speed or Cadence sensor. It offers a near-foolproof setup, it’s compact, and it performs exactly how you’d hope it to. There’s simply nothing convoluted about it, and for someone who wants to spend as little time fiddling with gadgets and as much time riding as possible, that’s priceless.

If you’re in the market to augment your riding with some fun data to nerd out over once the ride’s complete, you’d be hard-pressed to find a better sensor than what PowerTap has on offer. If you’re looking to add a bit of number-driven analysis to your training regimen, or if you just want to snag bragging rights on a particular segment of trail, then I’d recommend that you strap PowerTap’s sensor onto your bike’s crank or hub (depending on what you’re in to) and bask in the glorious data.

MSRP: $49.99

Thanks to PowerTap for providing their Speed/Cadence sensor for review.