Rule design in professional cycling

Via Lars Christensen, here is a combination of my favourite things:


Warning: Sports nerdiness follows.

The finding runs directly contrary to the conventional wisdom in cycling. The point of the change in the ‘red flag rule’ was to stop non-sprinters from trying to push to the front of the bunch at the end of the race. The massing of riders at the front was felt to be a recipe for disaster and the 3km change was intended to ease the congestion. The idea is that riders who aren’t involved in the sprint needn’t worry about staying ahead of crashes because they won’t be penalised time if they are stuck behind one. By changing the incentives the governing body intended to resolve a prisoner’s dilemma that was causing big crashes at the end of sprint stages.

The authors understand all that and suggest that the countervailing factor is that it insured riders against risk, which caused them to ride more dangerously near the finish. That’s a difficult explanation to accept because of the diverse nature of a cycling bunch. The sprinters are the ones most likely to take on risk to win the race, but they care little about losing time in a crash so their incentives are unchanged. The rest of the bunch has little chance of winning but some care about the time loss. Since there is no longer a cost to being stuck behind a crash they have an incentive to reduce their risk exposure. I struggle to see a good causal explanation for the results in the paper, although their magnitude is quite striking.

3 replies
  1. Logan
    Logan says:

    Nice, i wish i had thought of that for my honors report.

    Without reading through the paper i’d guess they have only accounted for a small portion of the risk. The rule change allows for the risk of time loss, but still does not allow for the risk of injury from crashing. For the majority of riders, staying close to the front and not crashing is their first concern, with time loss less of a concern. Perhaps an increase in road furniture is the reason for the increase in crashes.

    The worst part is this was seen as one of the UCI’s best rule introductions, i wonder what effect some of the others have.

    • jamesz
      jamesz says:

      Definitely only a small part of the risk but ceteris paribus and all that.

      It bothers me that the authors don’t seriously address the inconsistency between their data and the conventional wisdom. They acknowledge it but leave it rather unresolved. As you say, that leaves the question of whether we can trust the causal interpretation.

      “One of the UCI’s best rules” is a low bar these days!

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