The Sigma Sport BC 2209 MHR STS is a wireless bike computer designed for mountain bikers and includes everything that you will ever need to keep track of your performance, speed, cadence, hearth rate, temperature and an altimeter. There is also another version, the Sigma Sport BC 2209 Targa, that comes without the cadence sensor which can be bought additionally and it has silver panels on the side instead of black. Mounting the speed sensor was the easiest part, just make sure the distance between the sensor and the magnet is less then 15mm. Other than that there is not much to be said here, assuming that you set your wheel size correctly, the speed sensor will work as expected.
The cadence sensor on the other hand was a bit more trickier to mount, but It took less then 5 minutes to adjust it properly. The main problem was positioning the magnet and the sensor within the 15mm range without eighter one touching the frame or the crank arms.
Once you position them them right, you can forget about them, unless you manage to dislocate the sensor. In such cases you can simply reposition it. To check if the sensor is detecting the magnet on the crank arms look for a small LED light blinking each time the magnet is passing through. This is the case with the speed sensor as well.
The altimeter is not as accurate as the GPS on my iPhone, since it tracks the changes in barometric pressure to determine the change in altitude, but still it is quite useful. If you compare it with an actual GPS, you will find that it looses some meters in the total ascent count, especially when going fast through multiple uphills and downhills. The barometric pressure sensor does not react fast enough to catch the change in altitude, but this is an issue with almost every altimeter based on this technology.
The hearth rate belt on the other hand, reacts very well and quickly. The only problem I noticed is, when I rode close (1m and less) to a friend of mine who had the Sigma 2209 MHR Targa, but was not using his hart rate belt, his bike computer caught the signal of my belt. I do not know if the two signals will mix if the other person has his HR belt on, but I will try it and update this review.
The temperature sensor is accurate, although if you take it from room temperature to -5°C it needs some time to settle in.
As far as the battery life is concerned, I have been using the Sigma 2209 STS MHR wireless bicycle computer actively for four months and I still haven’t changed the batteries nor got a low battery warning.
What is in the box: Bicycle computer, cradle, speed sensor, cadence sensor, magnets, hart rate belt, wrist band, assembly accessories, battery compartment key, batteries (CR 2450 and CR 2032), instructions.
Pros: Waterproof, everything comes in the box (except the cadence sensor in the Targa version), durable, lightweight, easy to read, second bike support
Cons: None so far
Personally, I wish functions could have been grouped differently by buttons.