I'm a runner as well as a cyclist, but generally don't have any particular knee problems except each Spring when I get the bikes out again. It can also be aggravated by spinning classes if I go at it hard, so I am pretty sure this is cycling rather than running-related.
Anyway, it's an ache on the inner (medial) side of my left knee that bothers me a bit later in the day or the day after vigorous cycling. Interestingly, there is no pain if I run on it or while cycling -- just a general soreness that persists afterwards for a day or so.
Anyone ever had anything like this? I am assuming it will go away again this year as it has in previous years, but it's one reason (besides a cold, windy, rainy day) that I skipped a 10K race yesterday. I have a 5K to run tomorrow and a half-marathon on Sunday, so I hope that doesn't aggravate it too much.
I know this isn't a running forum, but it does seem to be cycling that brings it on (I've been running consistently all winter, and this just started when I got the bikes out). I don't think it's fit either, as it happened after riding both my road bike and MTB for the first times.