What's Cool In Road Cycling

PEZ-Tech: Polar’s CS400

Training time is more effective than ever with today’s multitude of data measuring and recording tools. With cycling computers that tell us key information like heart rate, speed, cadence, and altitude, a rider can tailor and analyze a training period, and easily make performance improving changes. The Polar CS400 is one of these tools, part of Polar’s cycling specific CS series of computers. Let’s take a look.

– Reported by Craig Griffin –

Opening the Box
The computer comes in a box with a head unit, handlebar or stem bracket, a speed sensor, the comfy new WearLink chest strap, and a couple of small instruction sheets, plus a CD containing Polar ProTrainer5 software for data analysis.

One of the sheets has a Getting Started guide, which steps through the installation of the sensor and set up of the head unit. Installation is really simple, with the head unit able to be set up on either the stem or handlebar, and the speed sensor a simple zip tie affair.

Set up is controlled through the head unit, which automatically steps you through all the setup settings, including mph/kmh, rider weight, wheel size, language, etc. It’s a fairly comprehensive set of inputs, but not difficult to do.

With everything on and speed registering, now what? Well, that’s a good question, ‘cause there are 5 buttons on the computer, so we head to the manual which is on the CD – so we printed the pages we needed.

The Speed Sensor straps easily onto the forks, and the mounting unit comes with built in rubber guides to protect the paint, and eliminate the need for electrician’s tape.

Using the Polar CS400
The Polar CS400 sets out to record a lot of data. Beyond the usual speed and distance functions, the CS400 has super accurate heart rate recording, programmable heart rate zones & alarms, and a full fledged altimeter that also displays slope percentage, total feet climbed/descended, max altitude, etc. Short of power, there is no piece of training specific information that is omitted… except cadence.

At $339, the CS400 does not come with cadence, but it’s a $32.95 option that can be added. Since cadence is important for training, I opted to add a cadence sensor, which mounts wirelessly on the left chainstay. Then it is a matter of turning on the option in the head unit, and you are good to go. I had no problem with the signal picking up cadence on my 56cm bike, but we’ve had little luck on 60cm+ frames – it seems the transmitter isn’t strong enough so Polar recommends installing it on the downtube. Even after mounting our transmitter on the down tube though, we still could not get it to read the signal.

The stem mount sets up nice & snug with two zip ties.

Normally, I would change the battery in the transmitter to make sure it was fresh – but the speed and cadence sensor batteries are non-replaceable. Polar says they’ll last “for 2500 hours of use and the sensors are covered for 2 years. Polar will send a brand new sensor if the battery dies within the first 2 years.” For the edification of the Pez public, I pried a sensor apart and found the common, inexpensive CR2032 watch battery.

The CS400 collects a fantastic array of data – everything a serious rider would want this side of power. Its accuracy is great, and the installation is easy and clean. And most importantly, downloading is possible into the excellent ProTrainer5 software or CyclingPeaks. But extracting that data while riding can be a confusing experience at times.

Button Layout
There is a large red button in the middle of the computer. Big, easy to see, easy to push, and used for only two functions – starting recording, and starting the lap counter… (stopping the recording is done by the tiny button on the left lower side.)

To get through the screens, you have to use the smaller, stiffer buttons on the right side. I started testing this computer in the winter with thick gloves – not the easiest experience to change screens. But I really wished the computer just started and stopped recording automatically. CS400 has an autostart feature.

The two buttons on the right scroll through the windows of data (forward or reverse- you can start to memorize the scroll order after some time to know which direction is faster to get the data you want). On the left side are 2 buttons as well, the top left turns on the backlight, while the bottom one stops recording. For me that backlight button could have been put to better use by scrolling through just averages or just maximums. The CS400 does have an auto scroll feature, but we had to search a few times to find it.

Like many heart rate sensors, Polar’s WearLink works best when the contact surface is moist.

Customizable Screens
Moving beyond the physical layout, Polar does make a good effort at being able to customize the data screens, to help you pick out the data you want. This can either be done with button combinations in the setup menu, or far more easily with the ProTrainer5 software. Basically you have groups of data that make up a window, and within that window you can customize what is shown. For example, in the altitude window, you can choose slope in %, slope in degrees, current altitude, max altitude, feet or meters climbed, etc. You get to pick 4 or 5, depending on the window.

Polar ProTrainer 5 Software is included, and makes customizing the data screens much easier.

The big red button is used for laps, which I don’t do too often in cycling training, but I thought it might be good for intervals. But in reality… not so much. If you hit the big red button while riding, it shows lap data – but in distance, not time (do an interval for .384 miles!), and only shows average heart rate after you end the lap. You can do intervals in time, distance, heart rate recovery etc. Further speed is incorporated in all the lap functions, but unlike running, speed is irrelevant for the most part in interval training. In running it is your effort marker, in cycling it has to do with terrain, wind, and style of bike. My feeling is that this feature is copied and pasted from running watches, without considering what a cyclist is doing.

Overall, the Polar performs like you’d expect from such an established brand – and it did pretty much everything exactly as promised. However, we had some problems with speed, cadence and heart rate, at different times and conditions. The chest strap wouldn’t start transmitting until the rider has a little skin moisture. This is no problem in the summer, but on a cold January morning, I’m not sweating too much. No problem, other heart rate monitors will have this happen as well, but I really don’t care about my heart rate for the first 10 minutes of a ride anyway. But Polar shuts off the heart rate signal reception after a few minutes of no signal. It does recheck for the signal periodically, and you can restart it by leaning down so the chest strap is within 3 inches of the head unit.

For speed, we had a problem with the speed cutting off to zero when going fast (40+ mph) downhill. My feeling was that the magnet was going by the sensor too fast, so I lowered the speed pickup on the fork, which reduced the angular velocity of the magnet. This improved, but did not eliminate, the problem. I never found a clear solution to this problem.

The cadence sensor can be mounted on the chainstay or down tube.

Downloading Data
Well after all that, there is peace in knowing that it was all recorded and stored. But be sure to remember to turn off the computer recording because if you forget it will fill up with data in a few days, Polar told us it will not record over data existing data, however.

Downloading is done via infrared port, which you can buy from Polar ($50) if your own pc does not have one. Once that USB adapter was plugged in, downloading to ProTrainer5 was easy & reliable. Plus configuration can be done graphically from the software to the head unit, rather than endless button pressing.

The Polar ProTrainer 5 software has a nice calendar style layout as a training diary. A ride is automatically listed when downloaded, and a double click shows all the relevant details of the ride in either data or graphical form. Extensive editing can be done with heart rate zones, your impression of effort for the ride, amount of sleep, etc. It is a full fledged, stand alone training diary.

The Polar CS400 is within striking distance of being a good, even great, computer. It displays and records a ton of data, although accessing this while riding could take some getting used to for people not already familiar with the Polar interface.

The download capability and software are excellent to make sense of all the data after you ride.

Personally I’d like to see screens that are completely customizable- let the rider decide what’s important, a slightly stronger cadence transmitter to work better with 60cm frames, and replaceable batteries in the sensors.

Overall the CS400 is worth considering for any data-junky, but may be more computer than a lot of riders actually need.

• Get More Info: PolarUSA.com

Where to Get ‘Em

About the Author: Craig Griffin is a 15 year bike racer and the owner of WiredBike.com, an online retailer of cycling electronics. He loves training with power and has extensive experience with many different power meters and cyclometers. WiredBike.com sells a large variety of electronic training devices for cyclists, including bike computers, power meters, hrms and electronic trainers.

Note: If you have other experiences with gear, or something to add, drop us a line. We don’t claim to know everything (we just imply it at times). Give us a pat on the back if you like the reviews, or a slap in the head if you feel the need!

PezCycling News and the author ask that you contact the manufacturers before using any products we test here. Only the manufacturer can provide accurate and complete information on proper use and or installation of products as well as any conditional information or product limits that may limit their use.

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