A question on tactics
 

I was watching CSC hammer away with Cancellara and Voight, et al and I was wondering why they don't use the TTT technigue where each would take a short turn at the front? Now, one guy will hammer away until he's wasted and then another guy will go as long as he can.

CSC wanted to save Sastre and the Schlecks. They would not have been rotating, and would have to repeatedly maneuver to let their teammates in. This would probably take more energy on their part. There's also the increased opportunity to crash - especially when they don't have the peloton completely stretched out. Much of the stage was uphill. Even the pros don't typically ride in the drops on climbs. Also, the aero advantage is much smaller at climbing speeds.

I am not a racer though, and I accept that someone may have more, or different reasoning.

You'd have the problem of the protected riders always having to grab the wheel of the rider rotating off. In a peleton with riders from other teams that wouldn't necessarily be easy, and would take energy.

Also a significant difference in the TTT is you can't drop riders as they're spent (you've got to finish with 5, and if you drop riders early you lose efficiency.)

On the mountain stages, you can drop O Grady after he's spent on the first climb, and it doesn't hurt the team effort, because he wasn't going to help you on L'alpe anyway.

So, the model as employed by Discovery, and now CSC, is you use your weaker climbers, who wouldn't be able to be of help on the last climbs where it gets tougher anyway, on the early climbs starting with the weakest. Use them for all they've got, and use them up one by one.