Cycling: a three week race priced daily
A grand tour outright is repriced every afternoon by a result that may be irrelevant, and the stages that matter are not the ones that get the coverage.
A three week race produces twenty-one results and perhaps five of them matter for the outright. The market knows this and still moves on the other sixteen, because money arrives after every stage regardless of what the stage decided.
The stages that count
Individual time trials and summit finishes. On both, the general classification contenders ride against each other with nowhere to hide, and the time gaps are real. Everything else is mostly a procession in which the contenders finish in the same group with identical times.
So a rider who looked dominant winning a flat stage has told you nothing about the outright, and a rider who lost forty seconds on a summit finish has told you a great deal.
Where the daily repricing goes wrong
The largest errors are on the day after a hard mountain stage. Fatigue effects are real, they persist, and they are extremely hard to observe from a result sheet. A rider who held on grimly and a rider who was comfortable finish on the same time, and only one of them will be there on Thursday.
Research helps here more than in most sports, because the qualitative reporting from the race, and rider interviews in their own language, contain information the timing data does not. That is the argument for running research before the model in its clearest form.
Team strength is underpriced
A leader with a strong team is protected from wind, positioned before every climb, and paced up it. Team quality is a large input into an individual result and it is priced less carefully than the individual is.
What this does not tell you
Crashes. A significant fraction of grand tours are decided by an incident that no model can anticipate, and a rider's crash history is a small sample of mostly bad luck.
Common questions
How do grand tour outright odds change during the race?
Sharply on mountain and time trial stages, and barely on flat stages, because the general classification contenders usually finish flat stages together in the same time.
Which stages actually decide a grand tour?
Typically the individual time trials and the summit finishes. A three week race is often settled by four or five days of racing.
Is a stage winner market related to the outright?
Usually not. Stage wins on flat days go to sprinters who have no interest in the general classification and lose large amounts of time in the mountains.