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Time Trialing – Variable Pacing

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Air resistance and wind are the nemeses of every cyclist. However, both can be used to your advantage in a time trial for free.

The faster you go the more mother nature tries to push you back. In simple terms, an average sized cyclist on a TT bike will need to produce 10W more to go from 30kph to 31kph. Going from 40kph to 41kph would require 20W. Therefore adding 10W during a slower part (headwind, hill, etc) will create higher speed than 10W in a faster segment. Variable pacing means that you can go (slightly) higher than your target wattage (past the redline) on slower sections and “recover” going under your target wattage in the easier parts. In a time trial where a second is a loooong time, with variable pacing you can gain from 12s to 42s over a 40km (25mile) course.

For example let’s take a 20km (12.5mile) segment with a 15kph (¬10mph) headwind on the opening leg and a 15kph tailwind on the return. To illustrate my point in the two charts below I am showing different pacing strategies for a cyclist with 250W and 350W FTP.

 FTP=250W Headwind 15kph  Tailwind -15kph
 Pacing  Power Speed   Time  Power Speed   Time  Total 
 Even  250W  30.0  40:00  250W  48.3  24:51  1h04:51
 Negative  245W  29.7  40:24  250W  48.3  24:51  1h05:12
Easy in, Hard out  245W  29.7  40:24  255W  48.6  24:41  1h05:05
 Variable +5W  255W  30.2  39:44  245W  48.0  25:00  1h04:44
 Variable +10W  260W  30.5  39:21  250W  47.7  25:09  1h04:30

You can gain from 21s to 42s just by pacing differently.

 FTP=350W Headwind 15kph  Tailwind -15kph
 Pacing  Power Speed   Time  Power Speed   Time  Total 
 Even  350W 34.8  34:29  350W  53.4 22:28  56:57
 Negative  345W 34.6  34:41  350W  53.4  22:28  57:09
Easy in, Hard out  345W 34.6  34:41  355W  53.6  22:23  57:04
 Variable +5W  355W  35.0  34:17  345W  53.2  22:33  56:50
 Variable +10W  360W  35.2  34:05  350W  53.0  22:39  56:44

As you go faster, gains are much smaller per watt, however, you gain anywhere from 12s to 25s.

With practice you can see how much above the redline you can go without burning out. Don’t fall into the trap to ‘save yourself’ during harder parts of a time trial so you can have power for the faster segments.  A powermeter is extremely helpful.

All calculations/estimations were performed here, using a 75kg cyclist on a TT bike, with all the default settings. The principle remains the same regardless of your position, etc so don’t get hung up on endless calculations and optimizations.

Conclusion

Variable pacing gives you precious seconds for free. With slight adjustment to how you use your power during a time trial you can gain anywhere from 12 to 42 seconds! Remember: Harder against the wind, easier with the wind.

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