I saw a bike at a rack that had a very thin chain guard bolted on the crank. It was bolted to the outside of the large ring on a triple. I'd really like one to ease my mind worrying about my pants all the time. Anyone know where to get such a product? I've got a 44t large ring with, I think, a 104bcd. It's a 4-bolt Shimano SLX crank.