I just got my first road bike about a month ago and when I bought the bike I had the shop put on a simple comp for me. For weeks I was thinking the computer was reading wrong or I had to come to grips with being a turtle named clyde if you know what I'm saying.
Well last week I am cranking in top gear, down a slight grade, on a nicely paved back road, fully tucked and staying with traffic (the speed limit is 35 mph). I look down at my computer and it reads 17mph! '17! come on!' I yell. So after I get back home from the ride I shower and decide to drive the loop in my car to check the milage...Bike: 12.6 miles, Car: 20.0 miles. Eureka! I'm not a slowmo my comp is just full of ****
After a re-calibration and a nice ride this weekend I was happy to see 25 miles on the bike, instead of 14 or so, and an average speed jump from 13 mph to 19.5 mph (ooh just below 20, but still nice to see) with a max speed of 35 mph, going down a big hill but hey I got it there...Horay for gravity I suppose.
Between this and my new clipless pedals/shoes it's like I never want to stop pedaling!