The UCI has issued a statement stating it is investigating "recent incidents" involving hookless rims and tubeless tyres "as a matter of urgency... in the interest of rider safety".
The statement follows Thomas De Gendt's crash at the UAE Tour, which saw his 28mm-wide Vittoria Corsa Pro TLR road tyre blow off a Zipp 353 NSW wheel, which uses hookless rims.
The fall-out from the incident saw Adam Hansen, the head of the CPA pro cyclists' union, take to Twitter/X, stating: "The @cpacycling is not happy with riders racing on Hookless system in the peloton".
Dan Bigham, a performance engineer at Team Ineos-Grenadiers, went as far as claiming "History will not be kind to road hookless".
While the cause of the crash was initially unclear, Vittoria subsequently issued a statement saying the failure occurred due to De Gendt’s front wheel impacting a rock, which caused the rim to break.
Hookless rims have become popular with carbon rim manufacturers in recent years. They are claimed to provide performance benefits including reduced weight, improved aerodynamics and more efficient manufacturing, with lower prices for consumers as a result.
Compared to a rim with bead hooks (sometimes known as crochet-type rims), hookless wheels are subject to stringent pressure and width limits.
De Gendt's team, Lotto DSTNY, told Cyclingnews the wheel/tyre combination run by its riders was "100 per cent in the rules". The combination is also officially endorsed by Zipp.
However, the latest ETRTO and ISO standards state the minimum nominal tyre size for a 25mm internal width rim – as featured on De Gendt's 353 NSW wheelset – is now 29mm, not 28mm.
The UCI's statement in full
In light of a series of recent incidents involving the use of hookless rims and tubeless tyres (a combination commonly referred to as hookless) in professional road cycling, the Union Cycliste Internationale (UCI) has decided to study the situation as a matter of urgency with a view to taking a rapid decision in the interest of rider safety.
These measures will be communicated as soon as possible.
The UCI shall continue to work closely with the stakeholders of cycling and equipment manufacturers to ensure that appropriate measures are taken both in the short and long term. This review and the decisions that will follow are part of the UCI's policy to promote rider safety, one of its major concerns.
