Ok ive just been out doing some freestyle and i found that my foot keeps on slipping off when i try to do really big pushs on stand up and ive noticed it with other tricks also.
Ive like how on the Dm Ringmaster Advanced they have the delves actually in the frame.
Any ideas?
Trev
skateboard grip tape?
What shoes do you have? When I first started stand-up tricks, I had a pair of shoes that were nearer hiking boots than proper athletic shoes, and I do seem to recall having problems with this once in a while. Another pair of shoes I got from the thrift store didn’t work at all for unicycling, because my feet slipped off the frame whenever I tried gliding, let alone stand-up tricks. I now have a pair of Converse High-tops which works great for stand-up ww/glide/koosh-koosh.
Addidas erm somethings 
No i wouldnt change the trianers, Its the frame thats the problem. Iv’e a semcycle frame and its only slightly differnt to my last one but less grip somehow.
Might try grip tape but i dont know how long it will stay on for.
Trev
I used to skate, and grip tape is pretty burly stuff. Just make sure that you use a strip that goes all the way around the frame, so you don’t kick the corners, which can tear it off really fast.
Maybe you should consider getting a new frame. The one on the Koxx-One freestyle unicycle looks great for stand-up tricks. The Nimbus II frame (which I have) has a similar fork, and it offers great support.
personally i dont really like the nimbus frame, Ill be buying a koxx trials so ill get to test it out.
Trev
Leo White put little rivets into the crown of his freestyle uni for grip. Alternatively if you were feeling super-clever, you could get someone to drill + tap some holes for a thread to fit allen key pedal pins, which would have the same effect, except you could replace them if you wore them down.
Grip tape is okay, gives very good grip, but it’s a bit mingy. You’ve got to be really careful not to have edges free anywhere or else it comes up and looks really rubbish. The rivet thing looks much much nicer.
Joe
If you have access to a welder you could eaither weld on small pieces of trip as on the Kh '04 frame or ‘noodles’ (i think they’re brake/gear cable guides) like on the KH '05 frame. Both of these were originally specifically designed to aid grip of the foot on the crown.
On my Pashley I sanded the curve and then painted on Evercoat “Skid-No-More”. It seemed to work pretty well and much better than skate tape. I haven’t tried it on a flat-crown uni though.