Does anyone have a cure for knee pads slipping off?

I`ve had a few high speed crashes and my knee guards get ripped down, off my knee cap, leaving it exposed to whatever nasties are on the ground I`m sliding across.

I`ve got a Rockgardn flak jacket that works a treat on my upper body but I can`t get knee guards to stay in place.

Any suggestions?

I take the Mountain Bike approach and use full length shin and knee guard. The shin section stops the knee protection moving down. I know FOX make some lightweight and breathable gear that works for me. Same goes for elbow and forarm protection.

Thanks for the feedback,
much appreciative,

I have 661`s and rockgardn knee pads and both the MTB full leg style but they seem to slip off in the same way.
I bought the rockgardn on the net and after they were slipping off I went the shop and tried lots of different styles, eventually walking out with the 661`s but they still come off.

I`m one of those tall stick leg guys so I think the thing I`ll try is the old tape em on.

I suppose I could always go "drag style" and try a garter belt