Alpinestars was unable to find any defect with the leathers of MotoGP title leader Fabio Quartararo during checks immediately after the Catalunya race.

The zip on the front of Quartararo's leathers came undone, for unknown reasons, through the Turn 1-3 area on lap 21 of 24. The Yamaha rider then discarded his chest protector and completed the race with the leathers open.

Although this put Quartararo in breach of the rider's safety equipment rules - which state leathers and chest protector 'must be worn, correctly fastened, at all times during on-track activity' - he was surprisingly not black-flagged and allowed to finish in third place.

That became fourth when the Frenchman was penalised for cutting Turn 2 late in the grand prix, then sixth place after another 3-second penalty was eventually issued late on Sunday evening for the leathers and chest protector infringement.

Exactly why the zip came down remains a mystery, Quartararo saying only that:

"I had the leathers completely open in the first corner and I just tried to put [the zip] back in a normal position again. I couldn't do it. When [the zip] is totally down you need to stretch [the two sides together to pull the zip back up], like a zip on a pair of jeans."

However, on the slow-down lap "it was possible again to close the zip" and Alpinestars have yet to find any fault.

'Following Sunday’s MotoGP race at the Circuit de Barcelona-Catalunya, the Alpinestars’ Racing Development team commenced an investigation into the integrity of Fabio Quartararo’s racing suit," read an Alpinestars statement provided to

'Upon initial analysis post-race in the Alpinestars Racing Development truck located in the MotoGP paddock, the team found the suit to be in normal working order with all zippers and fasteners fully functioning.

'Furthermore, all the suit’s componentry, including the Tech-Air® Airbag System, was intact and fully functioning.

'This is only a first assessment, to be further investigated once the suit is in the Alpinestars laboratory at Alpinestars headquarters, conducting all testing and analysis to understand more about the cause of what happened during the race.

'The Tech-Air® Airbag System did not deploy during the race, it functioned as expected as there was not a crash situation.'

Should further checks also confirm the leathers to be 'in normal working order with all zippers and fasteners fully functioning' it will add weight to the theory that the zip might not have been not fully closed at the start of the race.

Others believe the chest protector was the main factor.

Did it move out of position (possibly as the zip began to open, or even somehow causing the zip to open) and disturb Quartararo, prompting him to react?

Quartararo has not explained why he reached in and discarded the chest protector with such urgency, while still on the exit of Turn 3, potentially making the zip situation worse in the process.

It also meant that, even if Quartararo had been able to quickly zip-up his leathers once again, the lack of a chest protector would still have been in breach of the safety equipment rules.

Quartararo later accepted that he should have been black-flagged for the obvious danger caused by the leathers and chest protector situation, but maintains the Turn 2 penalty was unfair.

As a result of his demotion from third to sixth, the Monster Yamaha rider how holds a 14-point title advantage over Pramac Ducati's Johann Zarco, who finished the race in second behind KTM's Miguel Oliveira.