Change pace to improve your time trialling
Julia Shaw, women's winner, National 25-mile time trial championships 2013
When it comes to pacing yourself through a time trial or sportive, you probably already know that tearing off like a bat out of hell might get you a good time for the first few miles, but as that fatiguing lactate accumulates in your legs, you'll pay later.
However, setting a leisurely pace that allows you to feel good right to the end might leave you wondering just how much faster you could have been if you'd pushed harder earlier on, even if it meant dropping the pace later.
In recent years, research on pacing strategy has suggested that while an equal paced effort is the preferred approach by many cyclists, when it comes to the real world with hills and tail/headwinds, it might not be best after all.
Indeed, one study concluded that although riders should stick to a constant paced effort when external conditions are constant, when there are hilly or variable wind sections in the race, a variable power strategy may produce quicker times. However, these pacing studies have tended to use only a limited variation in cycling pace and over one fixed distance.
But now a new study by British researchers has investigated the effect on time trial times of a number of variable pace strategies and over a number of different distances to see what kind of pace variation (ie the number of pace variations in a time trial and how big each one is) affects performance at different distances.
In the study, the researchers used a sophisticated mathematical model of cycling, which (unlike previous studies) also included the effects of acceleration. The performance times were modelled using a hypothetical 70kg rider riding a 10kg bike in constant conditions.
The model was run to assess a number of different scenarios; the distances were varied from 4km to 40km and the researchers also looked at the effects of different average power outputs, ranging from 200 watts to 600 watts.
In each of these scenarios, the model looked at the effects of power variation amplitudes of five-15 per cent and also how the number of power variations (from just two right up to 32 variations) in the time trial affected the resulting performance. In addition to that lot, the effects of a ‘fast-start' strategy (and slower later) were compared with those of a constant power strategy.
In a nutshell
When it came to performance in the simulated 4km TT, varying the power improved performance at all the power outputs tested, with the greatest improvement being 0.90 seconds when the power was allowed to vary by ± 15 per cent.
At longer distances however, it was a different story. For distances of 16.1, 20 and 40km, varying power by ± 15 per cent increased times by 3.29, 4.46 and 10.43 seconds respectively. Smaller power variations at longer distances didn't have quite the same effect in terms of increasing time taken, but it was clear that at these longer distances, even power output was the fastest strategy.
What this study shows is that in constant conditions (eg on the track or on a still day on a perfectly flat course - not windy or hilly conditions) a variable power strategy such as a fast start strategy is only likely to gain you performance if the distance is 4km or less. At longer distances, it becomes increasingly important to stick as close as possible to a constant power output.
We do need to remember the results came from a computer model of cycling rather than actual trials (a model was used because time and cost constraints would make it nigh on impossible to cover all the permutations using real cyclists). Having said that, previous results from simulated models of cycling performance have been found to be remarkably accurate when verified using real cyclists - ie these results are worth taking seriously!
This article was first published in the August 1 issue of Cycling Weekly. Read Cycling Weekly magazine on the day of release where ever you are in the world International digital edition, UK digital edition. And if you like us, rate us!