Choosing my first bike I would like to get into biking. Haven’t ridden since I was a kid. Back then everyone had a one speed bike. The 10 speed English racer was the bike you dreamed of getting. I never had one. 

I’m in my early 70’s and live in W. Massachusetts, very hilly terrain. Up until a couple years ago I did a lot of inline distance skating (K2’s w/90mm wheels). My usual loop was 13 miles (21 km) and my longest trip was 26 miles (42 km). My legs are strong and I think I would enjoy biking. 

I’m finding the world of bike choices a bit confusing. Sport/hybrid, road bike, touring, fitness etc. Will be riding almost exclusively on back country roads and as I mentioned, I live in a very hilly area. Would like to work up to riding a 50 miler (80 km) eventually. I am 5’8” (172 centimetres), 145 Lbs (66 kilograms) 32” (81 centimetre) inseam, if that helps. 

I did some research and have come up with what I think I need, but am not really sure.


Sport/hybrid
aluminum frame
Flat handle bar
Triple chainring 
9 speed rear cassette 
Fully hydraulic discs brakes (because of the hills)
rapid fire shifters 
700c tires
carbon fork?


Would like to find a used bike for around $500 for my first bike to see how I like it. Hoping someone could tell me if I’m on the right track with my choices and maybe recommend a few used models I could look for that would work for me. 



Thank you, thank you for all the great input! I found and purchased a used bike which is like new and had exactly what I was looking for.

I decided to go with a double front chainset rather then the triple as recommended by a couple posters. Since I’ve never ridden a geared bike I felt that it would be a lot less confusing. This bike also has a carbon front fork and hydraulic brakes.

I’m going to use a flat parking area up at our high school to familiarize myself with using the gears.
Bicycles Stack Exchange prohibits recommending products, but we can offer principles to use when shopping.  

The key to choosing the right bicycle is matching the bike to the kind of riding you want to do. I apologize for the length of the post - this is a complicated topic.

Generally speaking, you can narrow your search to just a few bikes by:


Identifying the type of riding you want to do
Match a bike type to your need
Select a brand of bike
Filter for bike type and your price range


Matching a bike to your need
Starting with the beginning of the decision making process - you may have already thought all this out but I want to be thorough.  

Bicycles are designed for different kind of riding styles. Bikes are like shoes; there is a different shoe for every activity.
Looking at one bike maker's website offers examples:


Mountain


Cross Country
Trail
Cross Country/Downhill

Road


Performance
Gravel
Cyclocross
Triathlon

Active


Fitness
Transportation
Comfort



What's the difference?
The different types of bikes are designed for a type of activity, most of the names are pretty descriptive. What's different about each type are things like:


Frame geometry: this will determine how the bike rides, handles, and the seating position
Tire size: generally narrow tires are faster and less comfortable, wider tires are slower and offer more comfort and/or more traction for off-road
Appropriate drive train / gearing for the task
Appropriate brakes for the task
Wheels to match the application


In the original post the type of bike mentioned is "sport/hybrid". This style of bike indicates that the bike


Will be used on streets or paths
The rider prefers a more upright seating position
Tires in the medium-wide to wide range for greater comfort
Focusing more on comfort than speed


If these qualities match the kind of riding you have in mind then you have selected the right bike type.  

The original post mentions some specific parts. My thought is that some of the parts are "must have" (meet a riding need) and other parts are "nice to have"


Triple chain ring: this feels like a must have given the hills described
9 speed cassette: if you found a great deal on a used bike with a 7 speed cassette would walk away? 21 speeds will give you plenty of gear choices.
hydraulic disk brakes: nice to have. Any quality brake system will get you stopped on hills.
700C tires: for the riding style described the tire width seems more important than the wheel diameter. Do you want 40mm wide tires? Wider or thinner? If you find a great deal on a used bike with 26 inch tires is that a deal breaker?
Carbon fork: seems like a nice to have


Selecting a brand
Major bike makers are very competitive with each other in each type of bike and at each price point. Every now and then one maker introduces something that gives it an edge over another maker. Usually, it's only a perceived edge and not a measurable edge.
All that to say - in a given category and price point bikes are very similar.  

The one large exception are bikes sold in department stores. Department store bikes are built to hit a very low price point and large compromises are made in quality of materials and workmanship to achieve a low retail price.

One way of narrowing your brand choice would be to look at parts availability and support.

Used Bikes
The original post indicates a desire to purchase a used bike.
Evaluating the condition of a used bike is easier than evaluating a car but it still takes some bike knowledge to do a good job of evaluation. Here is a link to a previous question on buying used bikes with some helpful answers.

Even if you are looking for a used bike, drop by your local bike shop. A good shop is interested in helping people learn about bikes. They should be happy to answer questions and let you test ride a few bikes. The test rides are critical to verifying that you are looking at the right type of bike.