Wolfram Kurschat's grin glows with 420 watts. As soon as he has analysed the performance data from the bike race in Cyprus, he says a little too matter-of-factly: "I'm probably in a pretty good mood." In normal life, 420 watts means lighting 21 energy-saving light bulbs, running four LCD televisions or pushing the hoover across the carpet in economy mode. For cyclists, the indication of power in watts has a completely different meaning: it is an incorruptible measure of fitness. What's the point? Above all, it shows the condition of your legs.
420 watts in a race is world class
Do you have what it takes to be a World Cup biker or more of a cappuccino cyclist? If you want to know exactly, there's no getting round power meters. The devices record performance data (watts, speed and heart rate) throughout the entire ride. Professionals have been relying on these devices for years, but power meters can also provide a training advantage in the amateur class. A comparison with the classic power meter - the heart rate - shows exactly how. The heart rate is subject to many factors that cause distortions. Emotions, water loss, high temperatures or nutrition influence our pump. On the trail, this means that if you are firing along the trail at 38 degrees, you are forcing your heart to work hard. The same performance at 20 degrees less would be far less demanding. Watt remains Watt, regardless of whether it is raining dogs from the sky or whether you have drunk 20 espressos.
Training by heart rate or watts?
If you base your training on watt values, you can train in a more targeted way. This is because there are many variables that influence the values if you base your training on your heart rate. In addition, the heart rate reacts very slowly during short intervals.
Pulse training: advantages and disadvantages
- Favourable purchase price
- Versatile - running, mountain biking
- Very easy to install
- Poor, sluggish values during interval training
- Many variables - weather, food, etc.
Watt training: advantages and disadvantages
- Progress is recognised immediately
- Training stress can be calculated
- Extremely controlled training possible
- Expensive
- Assembly is sometimes complicated
Performance in competition: professional values in detail
Interval training according to watt values
Things are getting exciting with interval training, which is currently experiencing a resurgence. Rather than just ploughing through the basics forever, many professionals and amateurs are burning off short, intensive units. Heart rate is a poor indicator here. If you control a ten-minute interval with a heart rate monitor, you will ride too fast at the beginning and slow down towards the end. This is due to the inertia of the heart. The pumping muscle needs some time to switch to race mode. With intervals controlled by a heart rate monitor, the wattage fluctuates enormously. This is not the case with watt training.
In contrast to heart rate, wattage is incorruptible
World Cup ace Wolfram Kurschat sees another advantage: "When I ride my training lap at full throttle, the weather, the ground or my heart rate don't matter - the wattage is incorruptible and shows how fit I really am. Sometimes I feel totally rubbish during training and then realise later that I've ridden my best watts to date." If you want to train according to wattage values, you should determine your threshold power.
Software and literature for watt training
You can use these programmes to evaluate your wattage. Analyse your training data. We show you the software you can use to analyse your performance perfectly. From professional tools to low-budget instruments. We also show you two books for training with power meters:
Computer for displaying the performance data
Cheating is impossible with these computers. Whether with GPS sensor, puristically small or functional: these four models document your peak performance.
Cranks and hubs for watt measurement
They convert muscle power into raw numbers: Strain gauge strips in these cranks and hubs make it possible to measure watts. We show you five current models that are suitable for watt training:
SRM Powermeter
2856 Euro/703 g/www.srm.de
The mother of all force measurement systems - SRM from near Cologne - sends the expensive double X0 crankset with chainrings from the XX group (39/26) into the race. With its eight Dehmess strips, the wireless system achieves an accuracy of +/- 1.5 per cent. One battery lasts around 700 operating hours in the tried and tested system. The system must be sent in for replacement. The crank transmits the measured values to the computer at 25 hertz via the common ANT+ standard.
Powertap G3 Disc MTB
approx. 890 Euro/350 g/www.powertap.com
The alternative to the crank: The Powertap rear wheel hubs have proven themselves in our race track tests and allow power measurement via the chain pull, which arrives at the hub via the sprocket. The latest version has higher quality bearings, is compatible with thru axles (142x12mm) and weighs less than its predecessor. You can change the batteries yourself. If you have two bikes with the same wheel size, you can use the Powertap hub on both bikes in one go.
Power2max Rotor 3D
867 g/1230 Euro/www.power2max.de
The low-cost crank alternative comes from Chemnitz. The system works with strain gauge strips and is very similar to SRM's technology. However, the conventional CR2450 battery can be easily replaced after 300 to 400 hours. That saves money. The force measuring unit can be retrofitted to many common cranks and then costs only 690 euros. Unlike SRM and SRAM, Power2max does not require a magnet on the frame to measure the cadence.
SRAM Quarq Quatro
722 g (incl. bearing)/1651 Euro/www.sram.com
Like the Sachsen crank, the SRAM crank also focusses on user-friendliness. The CR2450 battery can be changed without tools. A small, additional frame magnet measures the crank revolutions. The carbon crank is similar to the X0 model and has ten strain gauges that determine the power with +/- two per cent. Like all other systems, the Quarq sends its signals in ANT+ encryption to one of the computers described below.
Stages Shimano XT M870/875
237 g/849 Euro/www.stagescycling.com
The new power meters from Stages come from America. The measuring technology is located in a small box in the left crank arm. Advantage: You only have to replace the left crank arm. Disadvantage: The power is only measured and extrapolated for the left leg. The accuracy is +/- two per cent. The Stages cranks are available for many Shimano and SRAM crank models, but not yet for carbon cranks. The CR2032 battery lasts around 150-200 hours and the cranks are available in four different lengths for single, double and triple setups.
You can find the detailed article on watt training from BIKE 5/2012 in the PDF download below.
