I hope I can explain this adequately. I carry a 3' + length of narrow webbing. It is actually part of something that mountain climbers use. To turn it into a chain whip you tie a knot in one end. The knot catches onto the teeth of the cassette when it spins as the wrench turns the lockring. The other side of the webbing is tied to the wheel. If this doesn't make sense I can take a picture. Until you need it it is very light & takes up little room. I am carrying it in a zip lock bag because the first time it is used it will become quite messy. Of course I also have to carry a crescent wrench & cassette lockring interface. The crescent wrench has been machined down narrow enough to work as a pedal wrench, and it will also work with my Phil Wood bottom bracket interfaces. I hope this makes sense!

Tom