Is this a normal experience?

[Zen]

I can't find that bike in a search
Did you go from upright to drop bars?

[pinkychique]

I bet the biggest thing is that you're just not used to riding. Riding made me really sore the first long rides I went on ( and riding a bunch of little ones has the same effect). I vividly remember lying on the couch wanting to die after my first 70 miler...so it's all about getting used to it.

The BIGGEST thing about your back: take the bike to a professional bike fitter to make sure it's the right measurements for you. I was lectured by my BF's dad (a doc) about how someone he knows rode a bike that didn't fit him and then ended up with a permanently messed up back.

Then make sure you do your core workouts! The core strength helps the back to do less work to hold you up in the saddle, so at the end of a ride you feel better. It makes a huge difference to have a strong core.

Keep on riding!!

Congrats on getting the bike not from Walmart!!