if you're riding brake less, then they do a whole lot... you want something that you're confident is going to bind your feet to the drive train...ive had cheap-o singles get loose on me going town a hill...not fun...

my current straps (MKS singles...the nice NJS ones lolz) have far better clasps on them that hold their position better. They're also built really nice... have not had a problem with them getting loose...

even so, i'm getting toshi doubles as soon as i can...i like to have the peace of mind that the straps won't give way anytime soon...