Hookless rims under CPA scrutiny after Thomas De Gendt crash at UAE Tour

Hookless rims are in the crosshairs of CPA (Association of Professional Cyclists) president Adam Hansen following Thomas De Gendt’s recent crash on stage 5 of the UAE Tour, with the Australian saying that the riders' association is "100 percent against" the technology.

Experienced Belgian De Gendt hit the deck at high speeds in the UAE on Friday in peculiar circumstances. Images after the crash showed that the Lotto Dstny rider's tyre had detached from the rims and the tyre insert had tangled with his fork.

In a post to social media after the stage, the Belgian suggested that he had hit something, causing the tyre to detach, although he wasn’t sure what.

However, the incident has raised safety concerns for CPA president Hansen who pointed the finger of blame solely at De Gendt’s hookless rims in an interview with Velo.

“This crash is why the CPA are 100 percent against hookless rims,” Hansen said. “Tires should not come off a rim. The maximum PSI these hookless tires can have put in them is 73, and if you hit something for sure it goes above the maximum 73psi rating on impact. That is why tires are coming off.

“We have heard from some teams that they have put tires on before, they left them out in the sun and their tires just pop off,” he continued.

“But the manufacturers really like them because it is much easier to produce the rim, you need less moulds for this. The rims are much lighter, it is easier for production so they are pushing for this.”

© © Tim de Waele/Velo Collection via Getty Images

De Gendt's tyre was detached after the crash

Hookless refers to the internal area that a tyre mounts to. Most rims feature a small notch that the bead of a tyre can hook onto, but hookless rims, as their names suggest, don’t.

The system instead relies on the tensile strength of the tyre bead to remain secure, along with tyre pressure. To ensure the safety of the system, ETRTO (European Tyre and Rim Technical Organisation) has specified that tyre pressure for hookless rims shouldn’t exceed the 73psi mentioned by Hansen.

• Read more: What are hookless rims and should we all be using them?

Issues can also arise when the incorrect tyre size is used for the specific rim dimensions. This could be where the De Gendt’s problem arose, as explained by Escape Collective, who confirmed with the team that the Belgian’s Zipp wheels were paired with 28mm-wide Vittoria Corsa Pro tyres. That falls below the 29mm minimum width recommended within ISO’s standards for a 25mm internal rim width, which De Gendt’s Zipp 353 wheels had.

This, of course, would point the finger of blame at De Gendt’s Lotto Dstny team for not following ISO’s standards, but the team defended themselves when asked about the incident by Cyclingnews.

“We use, obliged by the UCI, 28mm tyres on a 23mm or 25mm inner rim. That is according to all prescriptions by the UCI, from Zipp, and from Vittoria, so for sure we are 100% in the rules,” they said.

Whatever caused the tyre to detach from the rim, it appears that hookless rims will be at the forefront of the next safety debate within cycling.

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