Marc's Notes/Comments: The following excerpts from the article suggests that a "shallower" or slacker, less steep seat angle and a lower seat height protects the hamstrings. -- "...the Euro road-racers ride shallower, and with a lower seat height, to protect their hamstrings during long, arduous road stages..."  -- "...I was surprised at how low these riders run their seat heights when road racing, to help relieve--they say--pain in their hamstring muscles..."

What science says of seat angles - Article By Dan Empfield (June 20, 2002) from slowtwitch.com:
http://www.slowtwitch.com/mainheadings/techctr/seatangle.html

Marc's Notes/Comments: This article covers a few different scientific studies which study seat angles.  The studies did not take into account any aerodynamic benefits derived from changing seat angles (and consequently position on the bike), yet the results were surprising.  The studies reviewed in the article suggests and presents some scientific evidence that riding at a steeper seat angle (80 degrees) was more "economic" when it came to oxygen consumption than riding at a shallower seat angle (74 degrees).  The following excerpt summarizes why this might be:

"The authors only guess at the causes for the enhanced ability to perform with the steeper seat angle, and posit about the,

"greater contribution of the hamstrings and gluteus muscles (Heil et al., 1995). Although muscle recruitment cannot be determined from the present results, alterations in muscle recruitment or activation patterns can have the effect of distributing muscular work over a greater muscle mass (increased contribution of the hamstring and gluteus muscles) that would theoretically reduced the work rate per individual muscle fiber (Coyle et al., 1988)."

Juxtapose that statement, in which the operative phrase is "distributing muscular work over a greater muscle mass," with what Price says in the study above: "We speculate that increasing the tube angle improves effective force transfer during the second half of the pedal stroke." It seems that both authors feel that steep seat angles might distribute work over a greater range of the pedal stroke and in so doing lessen the peak torque that must be applied if should that power application be concentrated over a shorter arc."