Really a fan of the woolie - had never used one prior to this and never knew how easy it could be to clean (most of) the barrel of the wheel.
Three suggestions:
1) add one more in a smaller size
2) stiffen the handle/pole - I find when i go to really scrub, the pole flexes and it would be easier with a stiffer shaft (that's what she said)
3) maybe offer the smaller size at a right angle, as opposed to 45*. With a right angle, I would be able to get behind each spoke easily to do a more thorough job
Overall, I would rate the tool a B+ - makes the job a lot easier, but being able to get directly behind the spokes would be that final touch