POWER CAPABILITY MEASUREMENT ver 1: 9199

With our ability to calculate power over a wide range of speeds and grades we have the first step in finding your power capability. The second step is in locating a suitable hill of uniform slope and steepness - enough that you will be able to raise your effort close to your typical higher-level hill climbing ability. Look for a rather steep hill (5% - 6%) long enough to get a good workout.

I happen to have a hill that has a continuous climb of 220 feet (67 m) in .7 miles (1.13km) which is a 6% grade (I measured the elevation gain on a geodetic map). On a map look for elevation lines that are evenly spaced. This means the grade is uniform. Four lane center divided highways generally have more uniform grades (and wider shoulders). Try to get an accurate value for % grade because this will affect your results. The more accurate you set up the test the more accurate your results can become.

(Don’t forget this is an introductory process and as we learn and use spreadsheets along with taking data more carefully, more accurate results will be developed. This is far more meaningful than the use of general statements).

Now comes the physical work. Do your tests on a relatively calm day. You could put in a wind condition ( [-] for wind coming behind - passing cars) but wind is generally not steady. Also our calculators are set up for wind in line with the vehicle travel. This a calibration run so make it as pure as you can. Later you can play with wind values on your spreadsheet and see what that does.

Do a warm up ride, then go to the bottom of the hill, zero your odometer/bike/computer/timer. A heart rate monitor would be handy but not absolutely necessary. Now take a breath and start climbing. Try to climb at a uniformly hard rate and write down the time, distance, average speed, at a known stopping (distance/altitude) point. Don’t forget the Temperature and Barometer readings. Do at least three to four runs or until your body says enough. Go home. Have a cool drink and get out your spreadsheet programs.

If you do not know your CdA and Crr you can estimate by using RepChart.jpg. The effect of Gravity is so large that CdA and Crr values have a smaller impact for this test. Then insert the user values in the proper cells and read your power. For instance, for four runs on a 6% grade, with an average heart rate of 140 beats per min with a peak of 154 beats (close to my max) my average speed is 6.5 mph (10 km).,. This converts to .233 hp (176 watts) with user inputs of Eff 95%, CdA 2.4, Crr .007, Rider 160lbs (72.6kg), Bike 24 (10.9kg), Wheel wt 2 (.9kg), Barometer 30, temp 60 degrees F (15.56C).

Of course you could climb a lesser grade or climb slower to find what your more reasonable power level is (in my case this is about .150 hp, 110 watts). (If this power level seems very low wait till you get to my age!!). Do a few more runs on different days to see how uniform your data is. This also helps calibrate your internal sensation of what various power levels feels like.

FLAT GROUND TESTS

If you live in a area without suitably steep hills, flat ground tests can be used. Find a course where you can maintain a stable high speed for some period of time (races). Then use the data to determine your power level.

Suggestion; Review HPcapTXT.doc and HPcap.jpg