Tactical question: wheel sucking and marking

Hello,

I've been trying to understand some of the more detailed aspects of race tactics. One of the things that's been puzzling me is the tactics of marking, particularly in mountain stages in grand tours.

As I understand it, marking works roughly as follows:
rider A is the race leader in the GC. Rider B is A's main rival.
Rider C is A's team mate. C marks B by following him if he attacks A (so far so good?)

From what I've found so far, it seems C can either mark B by overtaking and blocking his progress (although blatant blocking obviously isn't allowed), or by sitting on B's wheel.

What I really don't understand is how the wheel sucking tactic is supposed to work: of course it's psychologically annoying to have a wheel sucker on your tail, but some sources claim it also somehow breaks up the pace and rhythm of rider B. But how? Is there some way C's wheel sucking can actually slow B down (aside from the psychological annoyance, which presumably an experienced rider can ignore)? I can't see how that could work.

As I understand it, the two situations in which C's wheel sucking tactic seem most likely to work are the following:
First, when C is also a contender for B's place in the GC - in that case, B will presumbaly not want to provide a slipstream or pacing or whatever help for C.
Second, if B's bringing C up to the front leaves B with two team mates together to fight against - if B brings C up to A, then A and C can eventually work together.

Does any of this make sense, or am I missing something about tactics here?

Cheers,

Johnny

From a physics perspective the wheel sucker does not slow down the rider in front.

Not sure about that......the rider behind expends about 30% less energy because the rider in front is moving "his" air out of the way. Because the air cannot join behind the front rider then doesn't drag increase for the rider in front.?

Shaun

PS plus it's a real put off when someone is "bogging" behind you

Shaun I don't believe that is right. Wind resistance comes form the front of the bicycle and rider so there would be no affect once the wind has passed by. Now if you were being drafted by something truly huge, like a blue whale, then there might be some "push forward" affect as the wind tries to get out of the way but that would be the opposite of slowing the rider in front?

Hopefully someone who actually knows about physics will chime in.

BTW I got the Moser!

BC established there is a minimal aero benefit ~2-3% to having someone on your wheel ... this was mentioned in a recent copy of Cyclist.

Now there's a surprise...................shouldn't have bothered about any hangers on as I time trialled off the front of the bunch

Shaun