In most respects no, but if you wish for a useful answer, you had better elaborate on exactly what you had in mind. For example, the way in which the cyclists crowd their neighbours as closely as possible, but as far as possible no more closely than possible, could be taken to resemble the way in which water molecules create surface tension through mutual attraction, and resistance to compression through mutual repulsion at close range.

The fact that cyclists differ in their intentions, for example because of differences in their tactics and merits, together with differences in their roles in their respective teams, leads to substantial differences between the behaviour of the crowd and the behaviour of fluids. Granted, within  the peleton their behaviour is unusually uniform, but not uniform enough for nontrivial resemblance or statistical prediction. For one thing, in discussing fluid behaviour, one assumes that the molecules are interchangeable; this is not true of cyclists for the most part.

Sorry to be so vague, but I think we need more detail to work on. For example I, for one, know next to nothing about competitive cycling.

Go well,

Jon

There is one way in which there is a superficial similarity: generally have to do with wind resistance. The riders at the front act as a shield for those behind, allowing them to use as much as 30% less energy. So, it is common to see the peleton adopt a shape that maximizes this effect. It is often very noticeable with a cross wind when the riders form a diagonal across the road.

However, since each rider makes conscious decisions about his behavior, this is not really acting like a fluid. In particular, when someone tries a breakaway, this means giving up pall of the protection of the peleton.

Exactly the same question came to mind when i saw them depart from Rotterdam three weeks ago.

The cyclists of the peleton keep together, like intermolecular attraction between molecules. If they behave like water, each cyclist would have an attractive force with typically four others. If pressed too much together they would suddenly experience a big repelling force. This means that at a low speeds the peleton would assume the shape of a circle.When forced through a narrow aperture the riders on the outside experience a viscous force from public and photographers getting in the way. And the riders at high speed tend to stick to the outside of a bend, as water does in a river bed, and at lower speeds stick to the inside, which has some similarity to the Coand? effect.Also the addition of small amounts of chemical substances appears to have a positive effect on the average speed.