Red Bull - BORA - hansgrohe have turned to an old-school tubular-era hack for Paris-Roubaix, coating the sidewalls of their Specialized Turbo Cotton tyres with liquid urethane. Subtly hidden on the teams racks, we spotted the sidewalls glistening with the gloopy substance. Initially unwilling to confirm what was going on, mechanics later confirmed it was indeed liquid urethane applied to the sidewalls though they didnt elaborate as to why theyd done it. Read more: The 4 Paris-Roubaix tyre tech trends you need to know about whats in, whats out, and whats controversial The team didn't elaborate as to why they've coated the tyres. The technique dates back to the tubular era, particularly in cyclocross racing, where it was used to prevent water ingress and protect delicate cotton casings from rot. Thats unlikely to be a primary concern in Roubaixs dry conditions. We expect its more likely being used to add a small amount of protection against the rough pav, and potentially reduce the chances of sealant seeping through the sidewalls. Other teams have turned to similar hacks to improve the resilience of their tyres. Notably, Visma-Lease a Bike has glued the beads of its tyres to their rims to help them seal in the event of a tyre burping. Specialized has been contacted for comment.