They average about 25mph for the tour. According to the professionals after 3 or 4 days of 100 mile stages it gets easier??? Of course ALL professional cyclers are on all kinds of "supplements" so maybe 22 mph by yourself would be equalvalent (no drafting). 20mph is SMOKING for a runner. 18 is a great average for 52 yr old me.
The heart rate problem.....I have chronically sore knees so must cycle in the warm weater...
Only by using the snap in shoes/pedals can I do it. I can now ride at tempo run heart rates and not get really tired doing it. An hour or hour and a half is about all I have time to do, but I feel that Daniels (2/3's bike time at running HR = running time) is fair. Your legs do not get nearly as much of a workout on the bike so it's a fair factor. The snap on pedals is the only way to go if you want anything resembling a real workout. They are dangerous until you get used to them as most people fall due to no "unsnaping" the shoes before stopping...