MikeF wrote:foxyrider wrote:cyclop wrote:I record rides in hours rather than miles to take account of offroad mileage ,then use 14mph as an average multiplier.275hrs so far,so 3850mls give or take.Unfortunately off the bike for an indeterminant period due to compressed femoral nerve so that will be it for this year.

Not doubting you but curious where the 14mph came from?

"Funny" thing averages.

If I travel a distance of 2 miles with the first mile at 10mph and the second at 20mph the average won't be 15mph.

I cover the first mile in 6 minutes and the second in 3 minutes giving a total time of 9 minutes.

Travelling 2 miles in 9 minutes gives a speed of 13.3mph. Travelling at 15mph would take 8 minutes.

In other words if you want a higher average speed, you need to travel faster on the slower bits rather than travel faster on the faster bits!

Average speed is actually very simple. If you have three people who are 18, 22 and 35 their average age is (18+22+35)/3 = 25. This is obvious as it's clear what the 'unit' you need to divide by is, the number of people.

If you ride for 5 miles at a constant 20 mph into a headwind and then turn and ride 5 miles back at 30 mph hour then it would appear to be an average of (20+30)/2 = 25 mph, but it isn't. That's because the 'unit' is not the distance but the time you spent doing each speed.

5 miles @ 20 mph takes 15 minutes so 5 mins @ 20 mph then 5 mins at 20 mph and another 5 mins @ 20 mph. 5 miles @ 30 mph takes 10 minutes. The total time is 25 minutes or five units of 5.

Taking the unit to be 5 minutes then the average is (20+20+20+30+30)/5= 24 mph.

10 miles at a constant 24mph is (10/24) = 0.4166 hours or 25 minutes.