Power Output - What is a Good One?

Many riders ask "what is a good power output for a cyclist?" and the short answer is "it depends". It depends how aerodynamic you are and how heavy you are because ultimately more aerodynamic, lighter riders will achieve higher speeds with the same amount of power. For this reason the mark of a "good" cycling power output tends to be quoted in "watts per kilo" i.e power to weight ratio. This makes a lot of sense when riding uphill, and at least some sense when riding on the flat, because on flat terrain aerodynamic drag is more important than weight, and because aerodynamic drag is significantly related to body size.

The Peaks Coaching Group has long published a Power Profile  relating rider wattage per kilo at key durations to a ranking of road race category, from "untrained" riders to "world class", although we understand that some of these categories were developed from interpolation. Perhaps the pinnacle of wattage per kilo is expressed in the oft-quoted metric that a rider capable of winning the Tour de France ought to be able to manage "6.7 watts per kilo on the final climb (of a summit finish)". Whether that factor evolved from or changed during an era of abundant doping, we dont know. But by this reckoning Alberto Contador, at 62 kilos, ought to be able to deliver 415 watts for 30 minutes. Miguel Indurain, however, ought to have been able to deliver 529 watts!

Power output though, is not watts per kilo, and the objective of this article is to identify a good power output. The simplest way that we can think of is to cast aside all issues of weight and aerodynamic drag by letting the reader define them. What you will find below is a table of theoretically modelled wattage outputs required to finish the most popular cycling time trials and triathon bike legs in a range of probable finish times. You define the riders aerodynamic drag and weight (remember to add 7 kilos or more for a bike) and we combine that with some reasonable assumptions to drive the calculation. Assumptions are:

  • A flat, asphalt course
  • Zero wind
  • The "standard atmosphere" at sea level (air pressure 1013mb, temperature 15 degrees C, relative humidity 0%)
  • 700c wheels with 23mm tyres
  • Drivetrain efficiency 97.6% (we quote power at the cranks hence power reaching the hub is 2.4% less

If you are uncomfortable with these assumptions you can always run your own scenarios in either the Power Components Model , the Power-Speed Scenarios Model , or the Power-Sector (Time Trial) Model .

Not all results you might calculate will be genuinely achievable (for example nobody is going to ride an sub-20 minute "10" without a very aerodynamic position) but anybody with a feel for what represents a fast finishing time will presumably recognise what is a good power output and what is simply off the scale. Keep in mind also that we are contemplating a flat, windless course. Even a few undulations and light winds would have a significant impact on required power.

Provided all of the above is understood we hope that these tables can serve as a "ready reckoner" to determine the mark of a good power output.

Aerodynamic Drag (CdA)
Weight (Kilos)  
Event Time (mins) Watts   Event Time (mins) Watts
10 mile TT 18:00 657   Sprint Triathlon (20km) 20:00 900
  19:00 563     21:00 782
  20:00 487     22:00 685
  21:00 425     23:00 604
  22:00 373     24:00 535
  23:00 330     25:00 477
  24:00 293     26:00 427
  25:00 262     27:00 384
  26:00 236     28:00 347
  27:00 213     29:00 315
  28:00 193     30:00 287
  29:00 176     31:00 262
  30:00 161     32:00 241
             
25 mile TT 0:45 645   Olympic Triathlon (40km) 0:54 380
  0:46 606     0:55 361
  0:47 570     0:56 343
  0:48 537     0:57 327
  0:49 507     0:58 312
  0:50 479     0:59 297
  0:51 453     1:00 284
  0:52 429     1:01 271
  0:53 407     1:02 259
  0:54 386     1:03 248
  0:55 367     1:04 238
  0:56 349     1:05 228
  0:57 332     1:06 219
  0:58 317     1:07 210
  0:59 302     1:08 202
  1:00 288     1:09 194
  1:01 276     1:10 187
  1:02 264     1:11 180
  1:03 252     1:12 173
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