biking_fox said:I estimate I'm about my weekly average speed is about 1 mph slower over winter. I definetly ride slower in the dark - no matter how bright the lights it takes more concentration. The inclemant weather also has an effect. Weekly average is fastest on still weeks, no wind in either direction. Even on lucky days with a strong tailwind, the reverse ride into a strong headwind is a greater reduction ins speed than the tailwind boosts it.