I am new to biking and mainly am doing it for the health benefits. I have L5 lower back disc problems, and my chiropractor told me to develop my core muscles (front and back) which would strengthen my back. I hate doing routine exercises at home, so I thought I might give biking a try. Other than leg muscles, what other muscles are strengthened.
Scott

Although biking does help back muscles, usually people do other exercises to strengthem them so biking gets easier. Talk to your doctor.

I have problems with L4-L5, and L5-S1 causing tremendous sciatic pain. Riding my bike is the only activity that I can enjoy comfortably. My Chiropractor encouraged me to continue riding since it stretches the spine and relieves the pressure on the disc.

Biking is not particularly good at developing core strength or flexability but it is better than doing no excecise and an excellent way of fitting activity into your everyday routine. Try cycling to the pool and swimming.
You have to take care that you are riding in a stance that suits your stength and flexability. A good starting point is the touring position with your back straight and at about 45 degress. Racers may select a lower position. Casual riders go for a more upright one.

Beware of rifding with a bent back; the classic mistake is to place the bars too high and close then hunch the shoulder and bend the spine to get lower. Check out your stance in a shop window reflection.

It can be good or bad on your back.

For me, i found my back likes the lower down "racing" position. The upright powition puts a good amount of strain on it, so I do need a springer seat for upright riding.

Pretty much, there is a component to make any riding style comfortable.

As for developing yout abs...which are part of your core....go do some specific abdominal excercises...cycling is not really a very good ab workout, unless you are doing trick riding, which is NOT reccomended for those with bad backs.

Cycling is primarily a cardiovascular and lower body workout.