For some values of 'rigid', yes. Here's a bicycle made out of nylon: https://www.bikeradar.com/news/airbike-nylon-bicycle-first-look/ https://www.bikeradar.co

For some values of 'rigid', yes. Here's a bicycle made out of nylon: https://www.bikeradar.com/news/airbike-nylon-bicycle-first-look/ https://www.bikeradar.com/news/airbike-nylon-bicycle-first-l... > Two British engineers have designed a bike, christened the Airbike, made entirely of nylon – and they claim it’s as strong as steel.