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REGULAR versus RECUMBENT cycling

Leo Rogier Verberne


B. Speed

My experiences as a touring cyclist for 8 years on a regular racing bicycle and for 10 years on various recumbent bicycles raised questions in my mind. At home in North Brabant, I was significantly faster on the high and the low racer (both recumbent bicycles) than on my regular racing bike. But during cycling holidays the Alpe d’Huez for example proved scarcely climbable on a recumbent bicycle. How to explain these differences in speed between a regular and a recumbent racing bicycle on a level road and during a climb?

B 1. Pitfalls


Errors are often made when comparing two bicycles in terms of their speed.

1. Competitions
Confrontations between regular and recumbent riders (figure 1) are very telling about the difference between the riders in terms of pedaling power and stamina, but little about the difference in speed between the bicycles. The pedaling power of men of the same weight varies considerably: between 150 to 425 watt (1). And so the drive (pedaling power) is not the same if you compare bicycles with different riders. In the case of a race between a touring cyclist on a recumbent bicycle and a professional cyclist on a regular racing bicycle (figure 1), no one can expect the recumbent rider to be faster. The professional would also win if cycling recumbent because he has a much greater pedaling power. When comparing both bicycles with the same rider, it yields so-called ‘paired observations’ (figure 2).






Figure 1 Competitions mainly compare the riders




RV low racer

touring cyclist
(Photographie L’Alpe d’Huez)

Michael Rasmussen

professional cyclist
(photo Cor Vos)






Figure 2 Paired observations, with the same rider,
compare the bicycles





RV low racer

recumbent racing bicycle
(Photographie L’Alpe d’Huez)

mijn racefiets

regular racing bicycle
(Photographie L’Alpe d’Huez)

2. Heart rate monitor
To know that the driving force of bicycles is equal you will need a power meter. In the present year 2020, 99% of all non-competitive cyclists still lack a power meter on their bicycle. Instead, a heart rate monitor is often used as a measure for the level of effort achieved (figure 3). The same heart rate should mean equal effort (pedaling power). However, the above only applies to the same rider on the same bicycle. Because the heart frequency is higher on a regular compared to a recumbent bicycle at the same level of effort (see Heart rate). And at the same heart frequency, the pedaling power of the same rider on the regular racing bicycle is lower. So a heart rate monitor is not suitable to compare the effort made on different types of bicycles.

hartslagmeter

Figure 3 Heart rate monitor: chest band and display

3. Air resistance
The importance of air resistance for speed appears from two world hour records: Chris Boardman rode on a specially constructed time trial bicycle (figure 4) a world record of 56,4 km (3). By contrast, Sam Whittingham rode in his streamlined recumbent bicycle with a shell (figure 5) to a distance of 90,7 km (2). In spite of a huge difference in weight between the bicycles in disadvantage of the recumbent bicycle. Hence, when cycling so fast it is not the weight (rolling resistance) but air resistance that is of decisive importance for the ultimate speed. However, measuring air resistance in a wind tunnel is expensive. That’s why the two components, front surface and Cd (draft coefficient, as a measure for streamline), are estimated most of the time. But errors in these estimates have substantial consequences for the calculation of speed.

Chris Boardman

Figure 4 Time trial bicycle, hour record 56.4 km
(Chris Boardman; Getty Images)


gestroomlijnde ligfiets

Figure 5 Streamlined recumbent bicycle, hour record 90.7 km
(Sam Whittingham; Varna Innovation & Research Corp.)

4. Climbing plus descending
The ‘climb time trial’ of Beek-Ubbergen is held annually in the hills surrounding Nijmegen. Virtually all of the participants ride regular racing bicycles. Yet the record time was set by a recumbent cyclist. This suggests that you can climb faster on a recumbent bicycle. However, that conclusion is incorrect. Because this so-called hill climb time trial not only involves climbing, but an equal extent of descending as well: the difference in height between start and finish is just a few meters. And so, if your climb on a recumbent bicycle is slower, but your descent is much faster, you can make good on falling behind during a climb. Moreover, the slopes in this time trial come one after another, and so the greater descending speed of the recumbent cyclist will give him an extra boost when climbing the next hill. Which is how he can be faster, even though he is the slower climber. So if you want to compare two bicycles in terms of climbing performance, then the test should not involve any descending.

5. Preconceptions
A comparative study should preferably be conducted ‘double-blind’. For example, when testing a new drug, its effect is tested in relation to a placebo (fake pill), while the subjects nor the researchers know which pill is the actual drug. That is what double-blind means. This excludes the effect of preconceptions on the outcome of the test. However, it is not possible to conduct a ‘blind’ comparative study of a regular and a recumbent racing bicycle. So you must be aware of possible preconceptions on the part of cyclists and/or researchers.

Conclusions
1. You cannot compare the speed of a regular to a recumbent racing bicycle using two different riders.
2. The heart rate meter is not suitable to compare the effort achieved on a regular bicycle to that achieved on a recumbent bicycle.
3. An inaccurate estimate of the air resistance (front surface and Cd) has major consequences for the calculated cycling speed.
4. A comparative study into climbing performance on different bicycles should not involve any descending.
5. Preconceptions in subjects and/or researchers may influence the outcome of a speed comparison between a regular and a recumbent racing bicycle.

Sources
1. Guido Vroemen : 'Watt it takes'; Vermogensmeters als hulpmiddel voor de fietstraining. Triatlon duatlon sport (2008)
2. Wikipedia.en: Sam Whittingham
3. Wikipedia.nl: Werelduurrecord (wielrennen)

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© Leo Rogier Verberne
ISBN/EAN:978-90-830515-1-2
www.recumbentcycling.org