Sorry if this has been beat to death but I'm getting ready for my first serious ride ever and need some advice. I am currently a runner and looking to do some cross training. I believe will be cycling 1-2x per week swimming 1-2x and running 3-4x. I'd like some advice on how far you think I should ride and just some general guidelines.

I know the basic hand signals.
I know to always wear a helmet.
I live in a very hilly area, but also have access to a flat road as well.
I am not afraid of some pain
I can am looking to ride for about 45 min-90 mins.
And I have a hybrid bike.

"I have a hybrid bike"

Ride that.

Since you're probably in pretty good shape I'd be thinking around 20 miles for openers and adjust after you see how that goes. Your tushie may be what dictates the length of your first few rides. It'll get better.

Thanks, will try 20 today And ya I'm expecting a sore ass

Put on some 700 X 28 tires

Learn to stand and pedal once and a while.

Your butt will love you.