AVG. Speed?

either way, if a wheel is a certain size, the magnet will pass the sensor at the same time. If you think of it your way, then it would matter where the sensor is on the fork as well.

I went for a ride today - 20km this morning and average 30km/h exactly which is about 18 and a half mph... Been cycling for less than a week...

when i ride alone i usually make avg 32kmph for about 40km.as i ride i often watch my cyclocomputer and i relize that i ride over that speed mostly (from 32-37kmph),but i have traffic stops.i am a girl 24years

don't have a computer on my bike, but i think we do ~20 on group rides i do about about 20 but they aren't really hammer fest.

H2Row said:

Why? Wouldn't it be more accurate if it is for the magnet's circumference?

If you want it accurate do a roll out of the wheel.

Mark the tyre and a spot on the floor - roll forward 1 revolution until the tyre mark touches the floor again , mark the floor.
Measure the distance between the two marks.
Program this value into your cycle computer for an accurate readout.

Average speed is irrelevant really unless you live somewhere 100% flat or consistently ride the same route without any interruptions. I can have a steady ride and average 18mph over an hour on the flat but have a blistering leg burner on some of the local hills and only average 12mph, surely this proves that Avg speed as a training aid is pretty useless?..

Thanks.