One for the mathematically gifted.

[Valy]

"What is P&L???????"

'Tis a dark and strange place hereabouts populated by Voldemorts. Innocent cyclists visit, and are never heard of again, a huge Black Hole, a gaping crevasse for the unwary, whole ships disappear. People mention the place in hushed whispers, as they do in Dracula films at the tavern when The Count's schloss becomes a topic.

Son, never visit the Politics and Life forum on CycleChat. I beg you....

I see. Indeed such forums... uhhh not for me.

Well, right now, and hopefully forever.

Just get a Garmin. Then you know it's going to do the distance calcs the same on every bike.

And, you don't have to worry about wheel circ' either.

And, you can put it in an arm strap and go jogging; or walk up Cader Idris; or use it in the car to record where you've been.

I'm sceptical about satnav speed measurement as the one we have in the car is about 6 MPH slower than the car speedo - and that is not in one car either.