Why can't runners cycle quickly

[Tin Pot]

Surely the tri position, as well as being aero puts less emphasis on/rests the quads? Most (endurance) "fun" runners have relatively weak hamstrings.

Yes, I think we might just be at cross purposes here:

The hypothesis was that a tri bike encourages the aero position and puts less emphasis on the quads.

But this isn't to take advantage of a runners physique, it's because there's a marathon to be ready for when you dismount.

If I recall correctly - the science is starting to catch up, and the aero position is the most important - if the course is relatively flat and the rider can maintain the position for the vast majority of the distance. I don't hear so much about the legs.

I'm weighing up the cost/benefit at the moment over upgrading my road bike. The tri bike isnt winning so far...