Image 1 of 5 Direct Energie were one the teams to trial disc brakes in 2016 (Image credit: Tim de Waele/TDWSport.com) Image 2 of 5 Tom Boonen (Quick-Step Floors) is using disc brakes in his final season (Image credit: Tim de Waele/TDWSport.com) Image 3 of 5 Kittel's Venge ViAS from the disc side (Image credit: Stephen Farrand) Image 4 of 5 Canyon Aeroad CF SLX Disc 8.0 Di2 (Image credit: Canyon) Image 5 of 5 Quick release skewers on the disc brake front wheels for Roompot (Image credit: Tim de Waele/TDWSport.com)

The CPA (Cyclistes Professionels Associés) has called on the UCI to ban disc brakes in professional road racing for a second time, and to organise an exclusive, 'all-on-discs' trial further down the line.

Cyclingnews has seen a copy of a letter sent by the riders' association to the governing body on Sunday in which it formally sets out its opposition to the reintroduction of disc brakes this season. Chief among its concerns is the danger posed by having different braking systems – and therefore different braking times – in the same peloton.

The letter, signed by CPA president Gianni Bugno and addressed to Mark Barfield, head of the UC's technical commission, with UCI president Brian Cookson copied in, criticises the UCI for failing to take into account the safety concerns expressed by a majority of professional riders.

According to the CPA, over 600 riders are against disc brakes in the form in which they were first introduced into the peloton last year, and the body set out three conditions when negotiating the 2017 reintroduction.

So far only one has been met: Tom Boonen and Marcel Kittel have raced using disc brake rotors featuring with rounded edges. However, protective casings – to further reduce the danger of cuts and burns – are yet to appear, and the 'mixed peloton' now being seen remains a serious worry for many.

The CPA has been part of ongoing discussions with the UCI, with the first of a specially created series of disc brake working groups taking place at the end of last month, but it has now formally expressed its feeling that the UCI is pressing on with total disregard for the concerns it has raised.

Cyclingnews reached out to the UCI for comment on Friday, and again on Monday, with the following questions, but is yet to receive a response.

What was discussed at the first disc brake working group and what course of action was taken?

Has the reintroduction of discs into the pro peloton been a success so far, according to the UCI?

Is the plan to continue with the trial in its current guise or will there be any amendments?

Does the UCI still plan to make safety casings compulsory for discs – and how close is the technology to being available?

Is the UCI considering a full, 'all-on-discs' trial, as proposed by the CPA?

Is the UCI paying sufficient attention to the riders, with two of the CPA's conditions not yet implemented?

Full disc brake trial

The CPA is proposing a trial during which all riders use disc brakes in certain races. This would involve every team equipping each of its riders with a disc bike so that they can get used to it at home and use it in training.

That would involve a lengthy interim ban on disc brakes – after the likes of Boonen and Kittel have already raced and won on them this season. CPA secretary David Chassot told Cyclingnews that it's possible for a trial to take place later this season.

Of course, the logistical headaches are numerous. First of all, some of the bike manufacturers that supply pro teams don't have disc-ready bikes available. Pinarello, for example, which supplies Team Sky, has purposely not produced a disc version of its latest Dogma F10 model, used by the whole team.

There's also the issue of budget, with some teams unwilling to use disc brakes let alone shell out for a full fleet of them. If non-WorldTour races were to feature in the trial, the Continental-level invitees, which operate on a non-professional and lower-budget basis, would have to be equipped and ready to race on discs.

According to Chassot, "The UCI didn't say yes but it didn't say no" when he first tabled the idea at the end of last month in the first of the working groups. Cyclingnews has asked the UCI whether the idea is under consideration but is yet to receive a response.

More on this story

Paul Voss, CPA representative for Germany, told Cyclingnews it would be sensible to wait until the start of the 2019 season to introduce a full trial, in order to give all stakeholders sufficient time to prepare.

Chassot would also like to see the UCI exercise more patience, saying, "We don't want to move too quickly and not guarantee rider safety."

However, in outlining that the proposed trial could take place later this year, he acknowledged that pressure is being exerted by the cycling industry, whose business model depends on continual technological advancement. As major sponsors that play a big role in financially propping up the sport, bike brands have considerable power and influence.

"The big brands want to push people towards disc brakes because that way there are fewer bike design options out there and so they can dominate the market even more. If everyone is on disc brakes, then it's easier for them," Fausto Pinarello, founder of Pinarello, recently told Cyclingnews.

The first of the working groups took place in Aigle at the end of last month, and Chassot praised the level of communication so far, though the letter, to be followed by a public statement later this week, represents a raising of the stakes.

"We have had very good discussions with the UCI. We are at the table with them and the teams and the industry and that's very important. But obviously we don't share the same agenda," Chassot told Cyclingnews.

"The only concern we have is the safety of the riders. Maybe we a creating a fuss about nothing, but maybe we are creating a fuss about a very real danger. If you have a big crash it's already too late."