Speed on Planks vs. Speed on Wheels

Here is the map of my 2011 biking season high (in terms of miles spun):

Hmmm, for some reason (I would call it a software defect), Google wants to show the area north of my ride rather instead of my ride. Drag the map upwards to bring my ride into view.. Note to Google QA team: time to file a defect!

The hard numbers are :

1. Total Distance: 19.2 miles (30.85 Km)
2. Maximum Speed: 29.7 miles/hour (47.73 Km/hr.)
3. Elevation gained: 1,052 feet (321 meters)

This top speed is entirely consistent with maximum speeds I get on my bicycle, seem rather slow in comparison to the near 60 mph I get on my K2 planks, no?

Actually, that 29 mph seems frightenly fast! I don’t want to say that my near 60 mph ski run was a walk in the park, it wasn’t I knew I was skiing very fast and knew a crash would be bad. However, a 30 mph run on skis does not seem at all fast to me while it seems very fast on my bike, why would that be?

I am guessing the surface I am looking at when I am in tucked on my handle bars seems a lot harder than the snow I am skiing on. Also, I am often times cranking hard on my pedals to try to get more speed to carry into the upcoming uphill or give me good momentum on the upcoming flat. That cranking makes the platform shift to & fro. I have bumps to deal with when skiing, but they rarely bother me, especially if I see them coming.

Maybe the fact that skiing is more about fun and recreation while biking is more about fitness. Who knows, I hope to test this all out again today!