Can bicycling cause runner's knee? I'm a longtime runner who has never, I mean NEVER, had any running-related injury before.

About 2 1/2 months ago, I started bicycling to my new job, about 5 very up-and-down, stop-and-go urban miles each way, a significant increase over my previous job where it was 1 mile each way, flat, and no traffic lights. I took a couple of weeks off of running to let my body adjust to the increased bicycling and then started up again.

Now, I've started having such bad knee pain that I can't run more than a mile. It only hurts when I run, and starts about 5-10 minutes into the run - it is a painful stiffness on the outside of my right knee. When I stop running or do other exercise, the pain goes away. I talked to my brother (who at one point studied to become a PT) and he said it sounds like runner's knee. So I got a foam roller and started rolling out my IT band 2-3 times a day, and it doesn't seem to be making much of a difference.

So here's my question: it seems like this is related to my new bicycling routine, since that's the only lifestyle change I've made. I am eager to hear if anyone else has dealt with a situation like this and how they were able to start running again. I do wonder if it could be related to my bicycle technique, or just in general the fact that my ride is so hilly and traffic-y. Or anything else that I haven't thought of.

People who don't bicycle just don't get this one - so I'd really love to know if anyone has some thoughts on this. I'm supposed to be running a marathon in March!
The Wikipedia entry for Iliotibial band syndrome suggests that some of possible causes may be


Inadequate warm-up or cool-down
Excessive up-hill and down-hill running
Positioning the feet "toed-in" to an excessive angle when cycling


This IT Band Pain Stretches, Treatment And Prevention article suggests "Having a properly fitted bike can help triathletes who suffer from ITB impingement while riding", and gives other advice.

Edit: This old answer may be useful also. 

I suspect


because it's such a short ride, maybe you are not warming up enough before you start.
the bike fit, despite your confidence that it's ok.
gearing: if you have to stand on the hills for long periods, then you need lower gears.


I recommend


stop riding now while you find the cause and find the correct treatment.
go to a specialist bike shop and get you, your bike, and your position (including foot position) checked, so that the fit is confirmed to be good.
get lower gears.
get medical advice. I like to see a physiotherapist for this kind of thing. Find one who is really into sports injuries.
depending on the medical advice, do some strength work.
when you resume riding, make sure you warm up thoroughly.
when riding hills, use the lower gears so that you spin more.


Edit: and I should add I am not a medically trained person.