The Scosche RHYTHM+ is an optical heart rate arm band with dual Ant+ and Bluetooth Smart transmission that is worn on your arm rather than chest or wrist. The Scosche RHYTHM+ was first released back in early 2014 and I decided to test it against the Polar/Garmin Ant+ chest strap on a walk, run and cycle.

Scosche RHYTHM+ Package Contents

Scosche RHYTHM+ package contents
Scosche RHYTHM+ package contents
Scosche RHYTHM+ instruction manual
Scosche RHYTHM+ instruction manual

The Scosche RHYTHM+ optical HR band is packaged with a small and large band, the optical sensor with dual Ant+/Bluetooth Smart, a USB cradle charger with a nice long cord and an instruction manual.

The instruction manual is brief the important parts being the recommended location as in this picture and turning on and off which I will cover in a later section.

Scosche RHYTHM+ Recommended location
Recommended location

Getting Started

Select the strap you think will suit your arm size and the location you are using, I used the large strap for both the forearm position and the upper arm. Thread the strap through either side of the pod and the velcro part folds over like this.

With velcro strap attached
With velcro strap attached

If you are using the RHYTHM+ on your forearm then you can probably just slide it onto your arm and then tighten, if using on your upper arm you may need to let one side out and then loop back in when it’s in the right spot.

Turning the RHYTHM+ on is as simple as pressing the button, press the Scosche logo in the centre of the grey cover for up to a second and the lights on the back will start like this.

Three lights on the RHTYHM+ optical sensor
Three lights on the RHYTHM+ optical sensor

There are two green LED lights and a yellow/orange one, this is the optical sensor it and works by transmitting LED light into your skin and soft tissue and measuring the light that is reflected back. Blood and tissue absorb and reflect the light at different rates so as your blood is pumping through your arteries and veins with each heartbeat the sensor is able to detect your heart rate.

Other optical sensors on the market only have green LED lights, the extra yellow/orange light is to enable more accurate reading of darker skin types.

Once the Scosche RHYTHM+ is turned on you simply pair it on either Ant+ or Bluetooth Smart to the device you use as you would usually pair any other sensor, I tested it on a Garmin Edge 520 with both Bluetooth Smart and Ant+ as well as with an iPhone, iPad and Android phone.

Then you are ready to ride, run or walk but I will skip to the recharging which you will need to do after or before 8 hours of use.

Simply snap the Scosche RHYTHM+ into the recharging cradle after lining up the charging terminals like below and plug into a USB slot of your pc or laptop. Recharge for two hours or until a solid blue light indicates it’s fully charged. Press the lever/tab on the side and unclip.

Comfort and Accuracy

I was due to do a gym workout the day I got the Scosche RHYTHM+ and that involved a 30 minute walk to the gym, an hour of weights and a 30 minute walk home. I paired my usual Polar/Garmin Ant+ chest strap to the Garmin Edge 520 and the RHYTHM+ to the iPhone and started both at the same time. Having never worn an arm strap HR sensor I was expecting it to be a bit uncomfortable and thought it would get in the way while lifting weights.

In reality it was the reverse, 10-15 minutes into the walk I was thinking this chest strap is really annoying. I have only ever worn HR chest straps while riding and I guess you get conditioned to how they feel. Using it walking or at the gym where I never normally wear one felt annoying. I fitted the Scosche on my upper arm and other than being a bit tight (more on that latter) it was never really noticed, which is what you want. Most times it was sitting just on the edge of my tee shirt sleeve so sometimes a bit visible, other times covered.

I won’t detail graphs of exact tracking to one another but they were pretty close together, the first 90 minutes the average between the two was only two BPM difference and the maximum HR was 3 BPM difference. The final 30 minutes the average was 1 BPM difference and maximum 2 different.

Probably the only negative of the Scosche RHYTHM+ so far was the tightness while using it on the upper arm, I was on the maximum setting on the large band. I know that’s not the recommended place but it works there and people will want it hidden if using it for cycling. It needs a bigger band if you have any sort of bicep muscle and want it hidden from view. Three different size bands would be ideal.

The next morning was ride time and I paired the RHYTHM+ up the same way again and did an 80 minute indoor trainer session with some maximum intervals near the end with 30 seconds on and 30 off to try and get my heart rate as high as it goes. I wore the RHYTHM+ on the recommended forearm location for this test.

As I was on the indoor trainer I was able to watch the actual and average heart rates live and it was noticeable that the RHYTHM+ lagged for the first minute and then from there on was recording virtually identical to the chest strap. The data revealed the same average heart rate and maximum during the intervals section.

The last test was a 40 minute run and exactly the same average heart rate was recorded and the maximum was only 1 BPM different.

From the limited comparison tests virtually no difference was detected from the optical HR arm band sensor to the chest strap.

Turning the RHYTHM+ off was a little hit and miss to start with, the manual says hold for 3 seconds, I found it was more like 3.5+ and once you release after pressing it takes a second to power off. Once I started pressing for more than 3 seconds there was no issue.

Summary


The Scosche RHYTHM+ is a unique product in that it’s dual band ANT+/Bluetooth Smart, it’s an optical sensor device and it’s worn on the arm instead of the chest or wrist and that will appeal to a lot of users who find chest straps irritating.

I found no issues with the accuracy and would recommend it based on what I used it for.

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