I compared the pedals in two tests on a flat course and two tests on a hill climb. The clipless pedals improved my time by 1.85% on the flat course and 1.9% on a hill climb. The overall difference was 1.88%.
The flat course is a 7.3 kilometer bike path running along a paved creek from West Los Angeles to the beach and the hill climb is 6.9 kilometers, gaining a net of 246 meters between Sunset Boulevard and Mulholland Drive.
The prevailing wind on the flat course is from the beach, and I average of 122 seconds more when going toward the beach than on the return leg. Most of the hill climb course is uphill – one climbs 358 meters – but there are short descents of 112 meters.
I did trials on four days. Each day, I rode one of the courses twice at my top speed, changing the pedals between the rides. The results of the four trials were:
Trial 1: I rode the 14.6 km round trip on the flat course using clipless pedals (1,586 seconds), changed the pedals, and then rode it again using pedals with toe clips (1,649 seconds).
Trial 2: I rode the 14.6 km round trip on the flat course using pedals with toe clips (1,595 seconds), changed the pedals, and then rode it again using clipless pedals (1,598 seconds).
Trial 3: I rode the 7 km hill climb using pedals with toe clips (1,823 seconds), rode quickly back down the hill, changed the pedals, and then rode up again using clipless pedals (1,844 seconds).
Trial 4: I rode the 7 km hill climb using clipless pedals (1,815 seconds), rode quickly back down the hill, changed the pedals, and then rode up again using pedals with toe clips (1,907 seconds).
Changing pedals took around five minutes, and the downhill ride about ten minutes.
This table shows the total number of seconds using both pedals on both courses. The bottom line is that the toe clips improved my times, but by less than two percent.
Of course, you would see different results. I am 67 years old, and riding an old bike -- a Raleigh Competition with steel tubing, Campagnolo derailleurs, and cheesy replacement wheels. There were a few days between each trial. I did not ride those days, but did run or lift weights. One cannot be sure that I rode all-out on every run, though I did my best. (I did not eat or drink between runs, which may have slowed the second leg a bit).
I believe these results are accurate for me. I will compete in a sprint triathlon later this summer. Based upon this experiment, clip on shoes would only save me about 20 seconds on the 10k bike leg, so I will be better off riding in my running shoes using toe clips, and saving the time to change shoes.
This experiment was simple and easy to do, and there could be many variations on the theme. For example, I would like to compare my current bike against a new one. I also pushed my highest gear throughout the flat course – I wonder whether a lower gear would have helped going into the wind.
Are you curious about some variation in your bike or the way you ride? Run an experiment and let us all know how it turns out.