Jean-François Bienvenue had retired from a career in graphic design when a host on a cycling trip put him on a Brompton. He rode one more than 1,600 kilometres across Italy and, partway through that trip, contacted the company to ask what it would take to open a shop on Saint-Denis. Cyclo Flex sells nothing else. The bikes are built by hand in London, weigh between eight and twelve kilos, fold in under 20 seconds and carry a seven-year frame warranty, which is the long way of saying you bring it inside with you rather than lock it to a post and hope. The range starts at the basic steel city model and climbs to titanium frames with carbon parts, with 20-inch-wheel and electric versions in between. Mechanics handle tune-ups, gear and brake adjustments, punctures and cables, and there are rentals and parts.