I think they're pretty hard wearing. I must admit I've not used 'em meself yet, though.

Talking of cx bikes, one of my Christmas presents turned up, belatedly, today. A DVD called 'Pure sweet hell'. http://onsuper8.blogspot.com/2006/03...weet-hell.html

Clip here: http://uk.youtube.com/watch?v=pkOhzvv-4vA