The numbers given for my last ride came from my CatEye Strada cycle computer and I am not sure how accurate those things are however my G/F computer showed the same numbers.
Your Strada can be custom-calibrated to your exact tire size, if you want the best possible accuracy. Pump your tires up, measure the exact distance that your bike rolls in one revolution of the front wheel while you're sitting on it, then enter that number into the Strada as the wheel circumference.
It sounds so simple when I say it like that
Working from memory, I believe you bring up the ODO reading, then hit the MENU button on the underside of the computer. The current wheel circumference appears, with the rightmost digit flashing. Clicking the computer's white rubber tailbutton advances the digit that's flashing.
Holding the white rubber tailbutton for a couple seconds brings you to the next digit. When all four digits are entered, hit MENU again to resume operation.
Doing a precise wheel-circumference measurement may be easier with a helper. Mark the tire, line the mark up precisely with a mark on the floor, sit on the bike (with your weight on it, as if you were riding) and roll as straight as possible until the mark is at the ground again. Have your helper mark the ground there, then measure the distance between the two marks with a metric tape measure.
I don't know about anyone else, but I need a while to get warmed up before my body feels like going at a decent pace. So if I tried to go fast for 10 miles, I'd spend part of it just getting to where I'm firing on all cylinders
On a rolling 20-mile route, my
Paramount currently manages about 18.5mph (two-way average) at an average heart rate of around 160bpm, if it's not too hot out. Bolting on my aero bar could get me another 2mph at cruising speeds, but I usually don't use it.