I've always had slightly dodgy knees, but recently the aching I experience in them has gone up a notch. It usually happens at the start of rides; especially under hard pedaling, but tends to improve throughout the course of the ride. I've been taking cod liver oil pills for quite a while.

So what suggestions do you guys have as to how I can stop the aching in my knees (I'm sure plenty of you have suffered from it too )? Any stretches perhaps (I know nothing about stretches and therefore, stupidly, don't do them ).

All help is greatly appreciated.

http://www.natural-animal-health.co.uk/glucosamine.htm

http://www.kneeguru.co.uk/insights/doku.php/articular-cartilage/overview4

i remember someone talking about how this sorted them out a while back

Meh, I'm only 15.

I'm 15 and I get it. Apparently it's just growth pains. i.e some parts of your knee grow ever so slightly faster than others and it can cause slight problems until it finishes growing and settles back down.

where abouts is the pain, is it in the joint its self or at the very top of your shin at the top of the tibia? if so it could be oschgouldshlatters (sp?) common in younger people who do lots of high impact sports at a young age.

if the pain gets to bad go to the docs, ask for a physio referal.

if not then, learn to ride a bit more flowy, not land so hard off drops etc

i get it just below the joints 

i get it in both knees and im only 17.
the worst bit is that i get it even when im not riding and it has now started to go to my ankles.
however if you wear a knee support (can be picked up from almost anywhere. i got mine from jjb for about a tenner) tight then i dont seem to get the pain or as much pain as i was in before.

makes sense. might try that my self actually.

would advise against the knee support thing though unless you need it as your muscles will become dependant on them if you keep wearing it, which isnt what you want