These are like tire balls but alot easier to maintain and install. They are called Tire Johnys. They are a huge hit in europe and are now making their way to the US. Im one of the first to use them and i can say from personal experience they do work and are about half the price. John Elliott is a muti time MX champ in the UK and is the designer of these Unique Product. I have let all the air out of my rear tires and ran them flat the other day just to mess around and didnt even notice they were flat. I think they will be a huge benifit to all xc races from novice to pro. Check them out here: http://tmtoffroad.com/[/b]
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