You could get a Dog Fang, but a Jump Stop is better
http://n-gear.com/whatis.html
http://www.billys.co.uk/english/group.php?prod=chng-js
A Dog Fang catches the chain when it falls off, a Jump Stop means in can't fall off. It also has the advantage of letting you adjust the stop screw to allow a bit of overshift, making a middle to small ring shift very slick.
http://n-gear.com/whatis.html
http://www.billys.co.uk/english/group.php?prod=chng-js
A Dog Fang catches the chain when it falls off, a Jump Stop means in can't fall off. It also has the advantage of letting you adjust the stop screw to allow a bit of overshift, making a middle to small ring shift very slick.