I've got Formula K18s on my mountain bike and I'm not that impressed to be honest. They've got a kind of spongy-ish feel (yeah, they're bled correctly before anyone says) which you may or may not like, and the power isn't as good as, say, a BB7 / Juicy or Hope trials (although this is only a 160). There's no 'bite' either, and the build quality is... average. I know this isn't very positive and perhaps that's not fair - they're decent enough but I wouldn't use it on my trials bike. Not sure about the K24s, perhaps they're loads better?! Either way, far better than anything made by Hayes