So first some quick background on why I ask this question:

Apparently I have been genetically cursed with insufficiently long hamstrings. I was actually completely off the bike for a year a couple of years back because of sore knees. I finally found a good physical therapist who does bike fittings and in a nutshell I think the biggest problem was just insufficient flexibility in my hamstrings which was causing my knees to not track correctly, causing some overuse issues. So I went clipless to help with alignment, focused on spinning vs. mashing and started stretching, rolling, etc. after every ride. So for the last five months or so I've been able to keep riding, but I still have small flare-ups where I get some patellofemoral soreness, or nights like last night where I could feel some serious tightness in my IT bands and hamstrings. My normal riding style probably doesn't help, since I tend to ride many times a day for short bursts (1-5 miles; commutes, trip to the grocery store, etc.) rather than long spinning sessions.

So with that preface, I've heard lots of different thoughts on stretching. The one that has always made sense is that it's like a stick of gum. If you try to stretch it when it's cold, it won't, but will just break. But if it's warm, it will stretch, thus the idea that you stretch only after warming up or at the end of exercising. Just curious if anyone has found this to be true or false and if stretching before riding might help me.