Guys i have a cateye light see pic and link,

the holder has a sort of wheel clamp but I cant seem to turn the wheel to loosen it, thus i cannot get the holder of my old bike and onto my new one.

Has anyone else had this sort of trouble with this or any other models, or able to offer me any advice on getting the think off

https://www.cateye.com/en/product_detail/343

Yeah, thats the crappy flex tight mount.
I use a pair of pliers to squeeze and turn the ring.

A blast of WD-40 will help too.

Yeah, I have one that uses that same clamp -- they suck. I've never had any luck with a Cat Eye product. I've got another one of their lights too - the compact opticube. The rubber strap mounting system never did hold the light very tight on the bar, so it would always droop and point toward the ground as soon as I rode over a few bumps, and now the little tab on the back that is supposed to secure the rubber strap has broken off. My next light is going to be anything other than a Cat Eye.

Left to loosen. I think the trick with these things is they should only be finger tight, and even then not tightened down real hard. I wrapped friction tape around my handlebars everywhere I mount something to give the mount something to bite into and hold it in position.

I had the exact same problem with mine. What I found is that if you pop off the little cap thing (that has the Cat Eye logo on it) that's inside the wheel, you can easily turn the wheel again. Then, when you get it tightened onto your new bike, you can just put the cap back on. I just used a flathead screwdriver to get it off.

thanks guys the pliers sorted it, a fwe bucks in kmart and were all good again