Saturday, April 18, 2015

Training By Numbers 2 - power2max + Garmin Edge 810


At the risk of repeating myself I'm going to revisit the arguments for using a power meter in training. I still find myself needing to explain the advantages quite often, which is astounding really considering the amount of information available on training now, and the simplicity of the logic. No modern cycling coach would even entertain the idea of coaching you if you didn't have one.

The numbers that matter in training for cycling are quite simple, and thanks to the mechanics of cycling, it's one of the easiest sports to get an accurate and clear indicator of athletic output since everything boils down ultimately to what you put through the pedals. Once we have the technology to measure the torque that produces, and with a couple of other simple measurements, you get a very clear set of numbers to work with that will also provide an unequivocal monitor of our improvement.

The 3 numbers that matter are:
  1. Power output - measured in watts
  2. Heart rate - measured in beats-per-minute
  3. Cadence - measured in pedal strokes per minute
These parameters together offer an exact representation of cycling efficiency and current fitness level. It is pointless to consider speed as a representation of anything of value in any situation outside of a race, since it is affected by a multitude of outside factors including wind direction, number of riders in the group, temperature, terrain, equipment and gradient.

The most important single representation of your ability as a rider is power output. This is unaffected by wind direction, aerodynamic advantage or even whether your brakes are rubbing for the whole ride! It is an absolute measure of your physical output as a rider. With heart rate together, it will indicate how much power you are able to generate relative to your maximum intensity. With cadence added to the equation it will indicate at which RPM you have the highest output for the least effort, and consequently your maximum efficiency.

With this in mind, it should be obvious that the most important addition to your basic bicycle setup if you wish to improve as a cyclist will be a power meter.

Heart rate on it's own can only indicate how hard your body is working, and much of this can be assessed by feel or RPE (Rate of Perceived Exertion). So it's usefulness as a monitor is limited, especially as it is relatively slow to respond to changes in exertion. Most effectively it could be used to make sure you don't go too hard on training units that are determined as recovery or long endurance.

Cadence again, while being a useful number to work with on it's own to some extent (generally the faster you can get your legs to pedal comfortably, the more efficiently your muscles resist fatigue), it is only when coupled with a power meter that one can accurately see at which cadence one produces the most power, which is pretty vital information, and will vary from rider to rider.


OK. Now onto the business of the gadgets that will get you this information. I previously did a review of the Powertap G3 power meter paired with the Garmin Edge 500. In the interim I've moved on, first to the power2max crank-based power meter, and more recently I've started using the Garmin Edge 810. Together these devices give me just about the best available feedback on which to base my training.


Moving from a rear-wheel-based power meter to the crank-based one, you obviously have the advantage of having the freedom of any choice of wheelset, so you can switch from your training wheels to your racing ones and still have all the same feedback. The obvious loss is that it is now fitted to your frame, so you can no longer have a power reading on other bikes by just changing the back wheel. That aside, the crank-based power meter is giving direct readings from your pressure on the pedals and so theoretically should be more accurate. It can also measure left-right variances better, and give you an accurate cadence reading.

I've been using the power2max now for well over a year, and it has so far proven to be super reliable and consistent. My initial choice was based on recommendations, reviews, the fact that it was significantly cheaper than the SRM and most other crank-based systems, and the fact that I trust German technology (!) It has no issues with transmission and is picked up by all my Garmin units immediately. I occasionally re-calibrate it, but it never really seems to make much difference. It does take a rather unusual battery, but I seem to get a good 6+ months of life from one battery.

The fact that I have little more to say about it, is really a recommendation. It does exactly what it's supposed to, and has never given me the slightest problem. If there was one thing I would wish for it would be slightly less weight - it's definitely heavier than just the spider - but then the new version of this meter is about 100 grams lighter.


It pairs well with my Garmin Edge 500, and I would probably never have switched to the more expensive 810 had it not been for my need to have a map function. The only other added function worthy of mention with the new unit is the phone link-up which gives you a "live-tracking" capability so people can see where you are. However, since you will need to be within a mobile coverage area for this function to work, it doesn't work much differently from a mobile app on your phone, and doesn't give me the desired trackability in the wildernesses that we sometime cross in our tours.

The 810 is definitely an improvement in functionality on the 500. Easy to switch between pages with the swipe of a finger, in either direction, it's easy to be quickly on exactly the page you need. Once you decide on the parameters that are important to you for reference while you're riding, it's much easier than the 500 to set these up. The software I've found more logical and user-friendly, and easy to find the functions you want once you get to know the thing a little.

I'm not so happy with the map function. I decided on the 810 as opposed to the larger 1000 specifically because of size - the 1000 is the size of a small smart-phone (consequently has a shorter battery life), and just becomes too much furniture on the handlebars. But the downside of downsize is that I find myself having difficulty reading what's on the tiny screen when it comes to following the maps. In fact in some situations it's downright dangerous to be trying to see what the gadget is trying to tell me. The instructions and warnings usually pop up in a font that's just a bit too small to be read clearly by my old eyes, so unless you have perfect vision that would be a note of warning.

OK, not the end of the world for most of what I'll use it for admittedly. The 4 screens/pages I have set up are perfect for what I need most, and have been selected to cater for specific situations. These are easy to read, and the less sections per page you choose, the larger the numbers are.

Page 1. For general ride information - 7 sections (from top down l-r): power, heart rate, cadence, speed, distance, gradient, elapsed time.

Page 2. For intervals - 6 sections: lap time, lap average power, heart rate, lap cadence, lap speed, lap distance.

Page 3. General ride info for bikes with no power meter or cadence - 5 sections: heart rate, speed, distance, gradient, elapsed time.

Page 4. Other useful info - 7 sections: total ascent, average heart rate, riding time, compass heading, average speed, elevation, time of day.

The next page scrolling to the right is the map. This will show you where you are currently, and if you download a route, you have the option of following the cursor and instructions to stay on the route you've chosen. Then there's a page where you can set up a target speed and see how far ahead or behind that you are during the ride.

Battery life is nothing like as good as the 500 which I could keep using for a week without charging, and because of the Garmin Connect phone app function (which uploads your ride as soon as you end it), and the fact that you don't really need to plug the unit into you computer at all, you need to remember to charge it every other day or so.

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