Fabian Cancellara is pulling the brakes on his hour record attempt while the Union Cycliste Internationale (UCI), cycling’s governing body, decides the rules. The Swiss cyclist reportedly planned an attempt on August 3 in Mexico.

“We are waiting for the UCI to set the rules for the hour record,” team Trek’s general manager, Luca Guercilena told Cycling Weekly. “Once we know that, we will know if the hour record will go ahead.”

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Cancellara closed his classics campaign with a win in the Tour of Flanders and on Sunday, a third place in Paris-Roubaix. When he spoke to the press in Roubaix, he would not explain his plans. Afterwards, he rode back to the black Trek Factory Racing bus, showered and returned home to Bern, Switzerland, for a break.

Guercilena had planned for Cancellara to race the Tour de France and to pull out early for the hour record. He put that plan on hold, however, while the UCI decides what type of bike cyclists may use for the attempt.

UCI President Brian Cookson said previously that he believes cyclists should be able to use a modern track bike position instead of the restricted Eddy Merckx position.

To prevent bike and position advantages, in 2000, the UCI wrote rules that required cyclists use traditional geometry bikes and setups as Merckx used for his 1972 record. It also rolled the record back to Merckx’s 49.431-kilometre mark. Since then, only Chris Boardman – 49.441 kilometres in 2000 – and Ondrej Sosenka – 49.700 in 2005 – topped the distance on traditional bikes.

“Cookson said they are supposed to go back to allowing cyclist to use time trial bikes but if that’s the case, we then know which record to beat. If it will be Rominger’s record or Boardman’s record,” added Guercilena. “As usual, if you want to beat something, you need to know what you want to beat.”

Guercilena said that he asked the UCI for clarification but he it has not response. If it were to allow track bikes like those used for world cups and world championships, it could re-establish the distance to Boardman’s mark set prior to the 2000 rule change: 56.375 kilometres.

The uncertainty also creates problems for Trek. The American bike manufacturer spent money and its engineers’ time to develop a 1972-style bike for Cancellara to use.

“It’s a big deal with Trek. It’s a lot of money to spend and time invested. We don’t know which direction to go, so it’s not so easy,” Guercilena said.

“The problem is, if they take too long… You know, you can’t just prepare the materials for an event like that in a snap. We were almost done with the bike and the wheels, and everything for the Eddy Merckx position. It’s a big pity.”