Sapient Chain Guards BMX Bike Chains are going to take your riding to the next level and here's how. Ok imagine this scene: you are riding your BMX bike, busting some serious tricks and overall rocking it. Then your pants get caught in the chain, you totally biff it and eat some asphalt. That sucks. And it could all have been prevented with a Chain Guard for BMX Bike Chains. Just bolt this protector over your chain and you can remove asphalt from your diet.