Power Increase of Clipless Pedals - Part 2

On Friday, I took the bike out for another ride, redoing the George Bush trail from 4 weeks ago. This time I had my clipless pedals and was ready to ride.

Unlike my ride from February 8th, I hit the halfway point and was ready to continue. I had to turn around and took a minute to refill my Speedplay waterbottle with the one on my seat tube. Unfortunately I didn't bring anything to eat, which I would later regret. As you can see from the graph below, I was met by the man with the hammer at mile 18 (right at the hour mark).  Despite my best efforts to tell myself to HTFU, I couldn't muster any sustained speed. I had to stop one other time to rest my bum and refill water again.  On Feb 8th, I had several rest stops, but the impact of the Honey Stinger waffle was evident during the last few miles.

Note: Speed indicated on charts exclude rest time

So what's power increase due to clipless pedals? It hard to be precise, because of different conditions.  Besides the rest and the food , the wind was a bit stronger in March (I may have had a wee tailwind at the beginning offset by a headwind at the end) and I had a month's extra of training (125 miles).

Compared to my previous post, I saw a speed increase from the start, but this could have been due to the wind in the first three miles. If we look at the entire distance to negate the wind issue, we have a bonk vs rest factor. So if we look at miles 4 through 11 (before the halfway point rest), we see a 14% power increase. Despite the rest, the power increase continued  to grow to 19%, before the bonk in mile 18.

Power in below chart back calculated using bikecalculator.com

Conclusion: I think the general conclusion from Part 1 was correct. Clipless pedals don't increase your power persay, but helps prevent you from losing power as quickly. So the title of the below chart should actually read power differential. Compling the two sets of data leads to the below graph.