Cycling Cadence and a Review – WAHOO RPM Cadence Sensor, Bluetooth and ANT+

brina-blum-114405I don’t do a huge amount of  super-intense high performance training, but I like to improve my biking (as well as running, weight-lifting, and everything else) here and there with as much training as possible (while still enjoying the hell out of my rides – something I couldn’t do if I was thinking about just training all the time).  

One big way to increase performance is to increase cadence – the RPM’s of your pedal strokes.

When we were kids we probably mashed on the pedals, I know I did.  Put it in the big front ring and small rear ring and pedal slow.  Sure, you could build up some muscle that way, but it was tiring.  

It was tiring because doing that uses a lot of fast-twitch muscles which fatigue quickly, take a long time to recover, and use glycogen for fuel instead of fat.  This glycogen is depleted fast in those fast-twitch muscle fibers, leading to higher muscle fatigue sooner, and higher oxygen consumption, etc.  

So instead you want to use a lower gear so you’re “spinning” faster, using your slow-twitch muscles which have better endurance, burn fat for fuel, and if you give them a chance more quickly recover from fatigue.  In other words – let the bike do the heavy work and your body do what it’s best at – aerobic performance.  That way you can go longer, farther, and faster.  And still build muscle and burn calories – but now you can pretty much do it all day instead of burning out  rapidly.

So in addition to dropping your bike into a lower gear you can monitor your pedal cadence or RPM’s for optimal performance.  Of course, you can count your rev’s using a watch.  But that’s not ideal, and you can’t monitor it for long periods this way – but it’s a good spot-check solution.  

The ‘average’ cyclist probably ride at 60 to 80 RPM’s, at best.  But the pro’s, as well as those in the know, are going to strive to ride around 90 on long level-ish stretches.  Sure, there’s a need for more oxygen intake at higher cadences but our bodies evolved for this kind of work.  Well-trained cyclists can ride nearly all day at a high cadence, while even a good cyclist is going to burn out their leg muscles at a low cadence and high, harder gear.

So 90 is right around a good number, it’s not THE magic number because everyone is going to be different, but it’s a good goal and reference point.  Thousands of cyclists who train hard know it, and it sure shows in race cadences and studies.  But not everyone can realistically use 90 as the exact goal or achievement point. 

I used to manually spot-check my cadence while road biking, and on the trainer – switch the watch to the time and manually count the pedal strokes.  But eventually I took it up a notch and worked on improving my cadence while on my bike trainer (see review here), using the Scosche RHYTHM Bluetooth Speed/Cadence Sensor (I reviewed it in this post).

This year I decided to do the same with my primary road bike, outside; where I put the most miles on.

wahoo_logo_lgSo, thanks to adding it to my Amazon wish list at Xmas time and my beautiful wife – I went with the Wahoo RPM Cadence Sensor.

I like the Scosche RHYTHM Bluetooth Speed/Cadence Sensor fairly well, it’s not the absolute best but it does the job.  I don’t particularly like how it looks on the bike, how it could be prone to getting knocked while riding outside, and it is both the speed and cadence sensor and for my outdoor use I only really needed the cadence sensor part as my watch has GPS for general distance and speed. 

So after a bunch of research I decided on the Wahoo RPM Cadence Sensor.

You will similar find clones out there, some cheaper and some with less ability to connect to other devices, less compatibility perhaps, and you will also find other sensors for cadence/speed that are bulkier and more visible/in the way (like the Scosche RHYTHM speed/cadence sensor).

The Wahoo Fitness Company is relatively new to fitness sensors and equipment, at least compared to a veterans like Garmin.  They have some great reviews, lots of things targeted toward bicyclists and runners, and seem to be held in pretty high regard in the world of fitness.  

But one of the reasons I bought this was I had a little experience with the Wahoo Speed Sensor, which I had bought for my wife’s bike.  It is similar visually, but attached to the hub instead of the crank arm of course.  And it seems to work excellently.  I also regularly use their Wahoo Fitness app (which works great with other sensors of all kinds) and they do sell both the Wahoo Speed and Cadence/RPM sensor together as a package, the preceding links also will show the sensor set with the bike computer option, as well as the heart rate monitor option.

And of course it gets generally good reviews.

prod154878_IMGSETThe Wahoo sensor is a small module-like sensor that has both Bluetooth and ANT+ and attaches to the crank.  There’s no magnet, unlike some of the old style cadence sensors and this one is JUST for cadence (see my links above if you are looking for speed also).  Like your smartphone’s motion detection; this uses a gyroscopic sort of chip and likely accelerometers.

It’s small, unobtrusive, made of matte-black plastic, waterproof (IPX7 – waterproof to about five feet), compatible with most anything that will accept ANT+ or Bluetooth 4.0 signals (it’s so-called low energy Bluetooth) – most biking phone apps (Android or iPhone), bike computers, watches, etc.  The battery lasts a long time, the company says a year, and is a replaceable, standard coin cell type CR2032 battery (no having to recharge it all the time) so you don’t need to buy anything special.  And the device has a one year warranty.

For the bike weight weenies out there it weighs in around 7 ounces and is only about an inch and quarter wide and an inch tall, and three-quarters of an inch thick.  So it’s thin enough to fit on pretty much any bike.  If your crank arm is closer than that – well, I guess you’re out of luck for mounting it to the crank arm but you instead can attach it to your sneaker (more about this later).  I have seen a few reviews where people mentioned that it would not fit their crank arm because of clearance – but wow; that’s close.

Just like Wahoo’s website itself the box it comes in is slick and modern but not garish, each part packaged in plastic bags.  Included is the sensor; with the battery installed, the gel-like rubber mount holder, zip ties, shoe mount holder, 3M double-sided tape, and a quick start guide and an important product info guide.

You may notice that as soon as you take it out the little occasionally flashing blue light will come on, indicating that it has detected movement.  Is the battery worn down a bit from all of the movement as it was shipped to me?  Possibly, but unfortunately there’s no easy way for Wahoo to stick one of those little plastic pieces in between the battery contacts and the battery to keep it from discharging; as it needs to be waterproof.  No way to do it without removing the battery for shipping.  My advice is to just check your battery level in the Wahoo Fitness or Wahoo Utility app – more about the apps later.

The included installation instructions were okay, pretty generic but really there’s not much that you need to figure out.  But I decided to double-check the installation instructions on their website just for fun.

Installation is one of three ways.  Unfortunately I can’t review the first two methods as I did not try them, but I can go over them quickly and review the last way.

Using  the heavy-duty double-sided tape that is included, the sensor can be for attached directly to the crank arm.  The tape is the good stuff.  Yet…  I’m not sure I can bring myself to trust it, despite a lot of good reviews by both road cyclists as well as MTB’ers.  A lot of people use this method, lots, yet I decided to go with the zip tie option.  But the double-sided tape course is probably the easiest and fastest way to attach it, you just have to make sure that your crank arm is clean and place the double-sided tape on it, stick the sensor to the other side of the tape, and give it a good squeeze and you’re all set.

On a side note – while writing this blog entry I came up with a great re-purposing for the double-sided tape, rather than chucking the tape or keeping it in a drawer – my Cycleaware Reflex Bicycle Helmet Mirror needed new double-sided tape from when I transferred it to my new Giant Horizon Helmet.  Rather than buying the manufacturer’s tape or a generic brand I used this tape from the Wahoo sensor; it worked great so I can attest to its strength even though I didn’t technically use the tape for it’s intended purpose.

The second option for mounting is a plastic mount with holes for your shoe laces to go through, so that it can be mounted to a shoe or sneaker.  You slide the sensor into the mount, lash it to your shoe laces and you’re done.  Good option if you are going to use it on multiple bikes, or a bike trainer at the gym operhaps.

The last method for mounting the cadence sensor is to use the small rubbery gel mount that the sensor just slips into, like a glove.  It’s very secure, and the mount has a slot at either side for the included zip ties to go through.  So you have two attachment points with this mount, which I like.  

Attaching it was simple, though as I mentioned above if your pedal crank is really, really close to any part of your bike when you are pedaling it may not clear it, I would guess that this would be very few bikes and the rubbery mount adds next to nothing to the thickness of the sensor.  I’ve read a few reviews from people who had a problem with their crank arms being too close and had to return the sensor, you’ll need to do a quick check of the distance that your crank arm clears your frame at any place.  This mounts on the non-gear crank arm, by the way.

20170307_165223It’s very inconspicuous, yet if you want to see the colored indicator LED through the gel mount it’s pretty easy to (from the opposite side of the bike).  In the daytime you can still see it, though of course you have to get fairly close if it’s in bright sunlight.

Mounting was quick and easy, with a quick snipping of the zip tie ends.  I may cut off and redo the zip ties a bit at some point but it is very inconspicuous.

So one way or another you should be able to get it mount and work with pretty much any bike – road, mountain, hybrid, gravel, cyclocross, recumbent, etc; people even use it with spin bikes.  

Pairing to my Garmin Forerunner 620 was simple too, exactly the same as connecting any other sensor.  The pedals have to be rotated a bit to wake the cadence sensor up, once you see the light come on you can stop rotating it.  I then set up current cadence in one of the fields on the first data screen on the watch along with speed, heart rate, and distance. A secondary data screen that I can switch to shows lap cadence and average cadence.  The accumulated data after a ride is downloaded by Garmin Express on your computer or phone, showing your cadence along with any other sensors and your stat.

Again, setting it up was simple and quick on the Garmin Virb (see my Garmin Virb Review here) too, with the cadence screen showing up automatically once I scrolled to it on the dashboard.  Once in use it shows a line graph, the amount of time as a reference, current RPM, highest RPM and average RPM.  Just like the Forerunner, this data can be downloaded, exported, etc.  Unfortunately the Virb only displays the data from one sensor at a time but the display of the data is more useful than the Forerunner in the form of the line graph. 

A simple pairing on the Wahoo Fitness app was equally as easy – in this case you use the app itself, not your phone’s Bluetooth pairing (make sure Bluetooth is turned on though).  The real-time cadence display is a bit simpler on the Wahoo app but shows a line graph on the summary screen after you finish, again you can export or upload all of your data to the most popular fitness/biking logging websites through the app, as well as download raw data in various formats.

virb
Wahoo Fitness App

Starting out for a ride requires the sensor to come out of sleep mode, which only takes a few seconds at which point it starts registering after that slight delay.  Likely you won’t even notice this as rolling your bike out of the garage or moving it a bit is going to bring it out of sleep, but some devices make take a few additionally seconds to start logging the cadence in real-time display.  

Some reviewers have mentioned drop-outs and spikes and such but I see none of this, it seems to be consistent.  And also accurate, when compared to manually counting my pedal revolutions while using a clock display.  I saw no difference in RPM’s between my manual counting and the display, and both the Virb and the Garmin Forerunner show the same cadence.  I don’t normally use the app for road biking but it seemed to also be the same when I did a quick test.

While the cadence seemed to be accurate and consistent across all devices there is a lag between the actual physical cadence and the display of it on the various devices.  From what I have read this is not uncommon for A) this device and B) other similar devices and watches, bike computers, what-have-you.  Some don’t seem to have any delay, some may be a second or two, some may be a bit longer.  I think the Wahoo Cadence Sensor works great, but this is one area where some people may find it annoying or something they wouldn’t use.  

Not for me though; even though I may sometimes train hard I’m not going to win any races nor expect to so my training and use of cadence doesn’t have to be exactly spot-on to the microsecond between actual cadence and displaying of it on whatever device I am using.  And frankly – if you are watching it all the time you’re doing something wrong and you probably haven’t developed a good feel for keeping the consistent cadence that you should be maintaining anyway.

With the Garmin Virb the lag for RPM update is around five seconds, with the Garmin Forerunner 620 it is around four to four and a half seconds.  The Wahoo app is around the same range.

The differences in lag times made me wonder if the lag is a combination of the sensor’s processing and transmitting of the data as well as the receiving device’s processing, logging, and display of the data?  If it were just the Wahoo Cadence sensor’s lag it should be somewhat consistent across all devices, I would guess.

Quick example - shaded blue = cadence, blue line = speed, green line = elevation

Example Snippet

Does the lag show up in the raw data or is it only in the real-time display on the devices I am using?  A look back at the data after a few rides using a quick, totally down-and-dirty, visual comparison between cadence and speed while corresponding the data points to fairly level riding seems to show that the data logging itself is NOT lagging, just the real-time display of it on the devices.  This, of course, is subjective without some really serious number crunching and heavy duty comparisons I believe.  [Quick example at left  – shaded light blue = cadence, blue line = speed, green line = elevation]  

Moving on…some people have mentioned spikes and drop-outs in sensor data, but as yet I have not seen anything like that.  Occasional spot-checks using the clock on my Virb, manual counting of my cadence, and a level section of road and comparing it to the cadence from the sensor by displaying it at the same time on my Forerunner seems to show good accuracy every time. 

Like all wireless devices there may be the possibility of interference in many forms, and possibly slight incompatibilities, bugs with certain devices, and things along those lines.  I have not experienced any of these.

One thing that could help solve any problems mentioned above, as well as being something that you should do anyway – is to make sure the firmware is updated.  This goes for all of your devices and sensors too!

With the Wahoo RPM Cadence Sensor you must use the Wahoo Utility app to do this.  It’s pretty easy and fairly quick, make sure you turn your pedals a bit when the app starts up to wake the sensor.

 

Cadence while riding outside

Cadence while riding outside

Cadence while riding indoors on bike trainer

Cadence while riding indoors on bike trainer

Both with the help of the Scosche RHYTHM Bluetooth Speed/Cadence Sensor (which I reviewed it in this post) on my trainer bike and the Wahoo RPM Cadence Sensor I’ve been able to increase my average cadence somewhat, to an average of just under 90 RPM (outside real-world cadence), and am still working on it.

 

One of the interesting things is comparing cadence while indoor biking on a trainer to cadence while outdoor biking.  Outside I coast and take micro-breaks in my pedaling as well as decrease cadence a bit going up hills, stop for this or that thing, etc – inside not really yet I am burning comparable amounts of calories over the same time period while doing each.  I believe that this is fairly typical of indoor trainer riding versus outdoor real-world riding – you tend to not take any of those ‘normal’ resting periods, coasts, and slightly lower cadences that you would get while on hills, fighting the wind, and other real-world differences.

It’s certainly been a worthwhile purchase for sure, and very useful (and very unobtrusive) addition to my cycling.

So summing it up about the Wahoo RPM Cadence Sensor – for me it works great, and for the price it is a great addition for my bike training.  I have had absolutely no problems or issues with the sensor so far, and while I would like the real-time display to have perhaps slightly less lag it is really a non-issue for me.  For the price, and for how well it works and what it does I don’t think it can be beat – unless perhaps you are a pro.

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