Really hot days when you're hammering along and ride over soft tarmac, its sticky, sounds like you're riding over cornflakes.
On holiday, walking down country roads, the smell of olive trees and the sound of cicadas in the tree and virtually nothing else...peace and quiet.
Psychodelic music.
Seagulls in holiday towns.
Then there's the powerful stuff...throbbing engines, the Merlin, jet engines in the distance...and one I remember like yesterday, the lowrumble of Vulcans taking off from Waddo or Scampton.