Friday, June 7, 2013
Training By Numbers 1: Powertap G3 and Garmin Edge 500
This is to be part of a series where I expound upon the merits of training by power measurement, and where I investigate and review a few options.
By now I think it should be obvious to most sport cyclists, but just in case: if you aren't training with a power meter by now, get one. It's the difference between shooting in the dark and having the lights on. Here's how it works.
If you want to improve as a cyclist, you need to train to be able to produce more power. Outside of race situations, you don't have to care about how fast you're going, all you need to concern yourself with is that your power is increasing through your training, for which you test yourself every few weeks. You can train for power over intervals of any duration in order to improve for the specific demands of your chosen challenge. If you're going to race up hills you also need to be very concerned with your power-to-weight ratio.
What you have in a power meter is completely specific, quantifiable information that tells you exactly where you are in relation to your goals, to each other, and also - somewhat harder to swallow - to the pros. It takes a specific amount of power to move a rider of X weight over course Y within a selected time. When I'm on my bike I care about only 3 numbers: my power output in watts, my heart rate, and my cadence. If I'm producing more power for the same heart rate, I'm improving. I can try out different positions, cadences, wheels, sport drinks, haircuts and whatever else I think that might affect my ability to produce power and transfer it to forward motion, thereby refining all of these things.
In training, I can sustain a set power for as long as possible and work on increasing the duration, or I can work on increasing the power output for a particular interval. I can collect data and see what my average power output is for a particular climb or route. No coach will work with you unless you have a powermeter. It is the number 1 training tool after your bike.
I got myself my first powermeter - a Powertap SL+ - about 2 years back. If you're not too familiar with the terrain, the Powertap system bases it's measurement of power on that which is delivered to the rear hub. It's not the top of the powermeter food chain, but it's the most affordable and regarded by most as accurate and reliable enough - used by many pro teams so it definitely works.
I initially had a few problems with the SL+ and after a couple of pit stops, Cyclops (who make the Powertap) replaced the faulty unit with the brand new G3 model. Already an encouraging recommendation for the product.
The Edge 500 is arguably the greatest little gadget a cyclist can have. You no longer need magnets on your spokes and odd little gadgets taped to your forks - it measures speed, distance, position, altitude, gradient (rather obviously) by GPS. It also does heart rate (via a transmitter strap), cadence (using the powertap or a sensor), and pretty much any info a cyclist might need. If you need maps, you go for something higher in the Edge range such as the 810.
Coupled with a power meter it will give you actual power, or averages over a series of durations. It gives you average lap power for your current lap which is a great and vital function for keeping intervals at the right intensity, or maintaining a set average power output on a hill climb for instance. Plus you upload it all to the Garmin Connect website and analyse everything you've done to your heart's content.
So back to the meter itself.
My choice was to get a 32-spoke version built onto a standard training wheel. It's mainly a training tool after all, and I trust the strength and durability of the standard wheel rather than a low-spoke-count lightweight that might have some flex. I might review that decision were I to start again. Once you start training with an indicator of your power output, it's hard to ride without it. I've ended up using it in races - that after all is the place where you really test yourself. In retrospect, a better choice might have been to get a 20-spoker and build it onto a durable but light racing rim. Moot point now.
Being the first power meter that I've used, I'd have to say that it was the expected metamorphosis in my training life. I have rarely ridden without it since. There is an issue of reliability there, as the readings can fluctuate with temperature changes, and I do seem to find myself "calibrating" - resetting the unit to zero - a couple of times during rides where I'm keen to get acurate figures. The batteries don't seem to last very long, and there's no indicator other than extremely dodgy readings to tell you that the batteries are going. The battery is easily replaceable though (easier than the old models).
The main drawback with using the hub-based power meter, is that you never get to use your rear wheels. I suppose it's saved me some money over the couple of years, since there's little point in looking at new wheelsets. However, the adavntage is that you can use the same power meter on all your road bikes - this is a big advantage to me as I live in 2 cities, keep bikes in both, and am constantly travelling between each with only a wheel to carry. Horses for courses.