Originally Posted by pdlamb

I'm usually one of the "go ask your healthcare professional," but in this case I'd call it optional. You've got a good chance of getting the slack-jawed, "you exercise 10 hours a week?!?" response from a non-cyclist. So instead, here are a few suggestions.

First, consider the possibility you need to ramp up more gradually. I'm guessing you didn't go from zero to two hours a day on March 25. So when you're aching a bit, tone down the next day or two's ride. Take an easier route with less climbing, or ride a shorter ride, or gear down and pedal easier. Mostly. You may still want to attack a short climb, but take it easier.

Second, concentrate on keeping a flat(ter) back and make sure you're not rounding your back. Especially when you're fatigued, that's too easy a trap to fall into.

Third, and pretend I'm writing my best Teutonic accent here, you must complete your core workouts regularly and often. Planks suck, but they're especially good to build up your lower back muscles. And keep up with the stretching, particularly your quads and hamstrings. This ties in with suggestion #2; you want to ride with the flexing in your hips, not your spine.

Good luck!