I pulled off a 24:01 on 12.59km on June 9th. Just a bit short of breaking 24 minutes. That works out to an average speed of 31.4km/h which is pretty good for me. Back on June the 2nd I did the 12.59k in 24:55. So all I need to do is 23:35 to get up to 32km/h which is the goal I am working toward. This means I need to cut 26 seconds off.
I got the 24:01 by watching my average speed. I have a pretty good idea how many 1/10th of a km/h I will loose on each hill so what I do is try to peddle up a surplus above the 32.0km/h.
For example on the above bike when I hit the 5km mark I was at 32.7km/h. My 1st 12.59km leg has a 300m hill at the 11km mark where I loose 3/10th of my average speed. Then the leg ends with a steep hill where I loose 5/10th off my average speed. Right at the end of a leg is not where you want have to deal with a steep hill.
I think I could do 12.5km on the flats at 32km/h without to much of a problem. So I am getting close to being able to do 32km/h for the first leg. I think another month and I should have it. Then I will have to work on doing the second leg (the first leg back to home base) at 32km/h.