I'm trying to ride harder, pushing up shorter, steep hills for under a few minutes pretty much until I crack. This has been producing a burning sensation in my quadriceps, nothing unbearable, but I was wondering what it is. I cooled down and stretch at the end of my ride to try and begin training right. Is this sensation normal? I'm looking at starting interval training this week and I feel like this could be a recurring thing. On a related note, is there a de facto training guide, a la Carmichael or some other trainer/author?
What you have is Delayed Onset Muscle Soreness.. the cause is unknown- it's probably not lactic acid buildup as was previously thought. It's common. Some people think that it's good, that having nearly constant DOMS means you're getting stronger. But I don't think so. If your legs hurt you won't be getting in a quality workout, which is important when you are doing intervals.
I think that DOMS after a long hard ride, or a tough interval session, is ok. But all the time? Probably not.
What are you training for?
For racers, Friel's "Training Bible" is good for figuring out how to plan your season.
lactic acid goes away fairly quickly. DOMS is your body repairing tiny tears in the muscle, which means bigger, stronger muscles when it's gone. I've had it last 4-5 days before, but that was after a lot of serious gym work. You will be able to work harder and longer the more you do it. Once your body gets used to the level of stress you are subjecting it to, you will have to push harder to trigger DOMS.