Possible Clues:

• (Eg swimming) with no prescribed method
• Skating competition
• Type of swim competition
• Crawl, usually
• Complimentary expression for all-in wrestling?
• Race where swimmers can choose what stroke to use
• Like some skiing and swimming
• There's no set way to win such races
• Tyres feel worn — so crawl?
• Crawl to the finish in such an event