Hi, quite new to all this cycling lark. I bought some dianese knee and shin pads from ebay because after stacking it big time at the weekend i have a monster bruise on my knee. However i've never owned kneepads before and have no idea how they're supposed to feel. Can anyone describe what i should be experiencing. They seem ok length wise and the straps tighten them up lovely but the top elastic bit above the knee cup slips down as soon as i move my knee, is this supposed to happen? THe knee cup stays in place so that's fine.

Bike's in the shop getting a bearing tune up so i'm not able to take them out and try them to see what they feel like.

Any ideas? Recommendations? Whatever?