TOUR: Were you surprised by the negative reports from professional sport on the subject of hookless?
Jakob Maßen: It is not unusual for racing accidents in professional cycling to lead to discussions about the choice of material. For example, when disc brakes were introduced. I was therefore not surprised by the discussion about hookless safety following Thomas De Gendt's accident. The incident is causing uncertainty, and because it can only be clarified by the parties involved, it offers plenty of room for speculation.
TOUR: The ETRTO (an association of tyre and wheel manufacturers that deals with compatibility issues; editor's note) has tightened its recommendations for tyre-rim combinations. For rims with 25 mm internal dimensions, a minimum nominal tyre width of 29 mm is now recommended, i.e. in principle 30 mm tyres, because nobody builds 29 mm tyres. Originally, 28 millimetres was considered sufficient. Does this change make sense?
Jakob Maßen: The ETRTO recommendations are discussed and adapted on an ongoing basis. They also take into account developments in the ISO. The bicycle industry is developing very quickly, and in fact there was a reduction in the recommended tyre width for 24 and 25 millimetre wide rims from 2022 to 2023. Schwalbe is a participant in the internal ETRTO debates, but I am not personally aware of the motives at the time. As this is only a recommendation and not a law, tyre and rim manufacturers themselves are responsible for ensuring product safety. Our tyres will continue to work with rim combinations from the original ETRTO recommendation of 2022.
TOUR: Is there any feedback from regular users suggesting that hookless is a problem?
Jakob Maßen: We have not received any complaints directly in connection with hookless tyres and our professional teams and athletes, who have been riding on hookless tyres for several years, have not had any negative experiences. The use of Schwalbe tubeless tyres (declared TLE or TLR) on Hookless rims that comply with the ETRTO dimensions is absolutely safe if the corresponding maximum pressures are observed. However, this long sentence shows that the topic definitely needs to be explained and that manufacturers need to do a lot of educational work to prevent possible application errors.
TOUR: Should you swap 28 mm tyres on wide rims with 25 mm internal dimensions for wider tyres?
Jakob Maßen: It is essential to adhere to the specifications of the relevant rim manufacturer. If they rule out the use of 28 mm tyres on their rims, you should follow their instructions.
TOUR: How does Schwalbe ensure that the tubeless tyres always hold securely on hookless rims?
Jakob Maßen: Product safety is our top priority. Our tubeless tyres have a particularly stretch-resistant bead core, which also makes these tyres hookless-compatible. The material is very expensive, which is why we also offer road bike tyres for use with inner tubes and without compatibility for tubeless or hookless in parallel. When developing bead cores, we have access to various laboratory tests, the most important of which is our bounce test, in which our tyres have to withstand at least one hour at 160 percent of the specified maximum pressure. We test well above the prescribed ISO standards to ensure product safety even under less than ideal conditions.
TOUR: Do the tyres widen over many years of use, so that the risk of them coming off increases over time?
Jakob Maßen: This must not happen to a significant extent, at least with the bead core. This poses particular challenges for the choice of material and construction of the bead core, which ultimately has to hold the tyre on the rim. Long-term tests are standard procedure, especially for new developments in the tubeless sector.
TOUR: Which part of the tyre is crucial for safety in combination with hookless rims?
Jakob Maßen: Tyres and rims must work well together at all times and should comply with ETRTO specifications. With tyres, the bead core with the correct circumference and high tensile strength is ultimately the decisive safety component.
TOUR: The safety pressure reserve of 110 per cent for five minutes specified in ISO standard 5775 is ridiculously low. Who is preventing the standards from being sensibly designed?
Jakob Maßen: As already mentioned, we at Schwalbe use a significantly higher factor of 1.6 of the specified tyre pressure for at least one hour. We know from decades of experience that this is a sensible value. We agree that the ISO standard with a factor of 1.1 for five minutes is clearly too low and does not take into account many imponderables. We would definitely welcome a higher industry standard.
