I have 2 bikes. one is a lightweight “touring bike” and one is a folding mountain bike. By touring bike I mean one with thin tires but not the ultra skinny racing tires. It’s designed for comfort. The mountain bike is heavy and cumbersome. that means it takes more energy to peddle. If you’re on a smooth trail I’d go with a lightweight touring bike. And
Now with that said you can go to a bike shop and tell them exactly what you’ve told us. they could let you test out a number of used bikes and then convert the one that fits you best to a folding bike or sell you a new folding bike that’s close. Whichever is cheaper.
NOTE: if you go with a lightweight bike that means the rims are light weight. It is the gyroscopic motion of the wheels that stabilizes a bicycle. as you decrease the weight of the rotating mass it is less stable. the reason I bring this up is so that you understand it is not the same experience as the bike you rode in your youth. If you take your hands of the handle bar it is not as stable. I know someone who tried to straighten the brake lever on a racing bike while riding it and literally pulled the front wheel out from under himself. It was an ugly accident.
Don’t buy a big box / Walmart type bike. They are literally engineered to last for about 75 miles before hitting the landfill. Buy a bike at a bike shop. If budget is a concern, find a used bike.
You don’t need 20+ gears. For your kind of riding 6 or 7 gears will be fine.
When I was in your position eight years ago (I’m 71 now) I ended up buying a Specialized Crosstrail. It has been great and problem free, but is simply more bike than I need. If I knew then what I know now, I would buy an Electra Townie. There are several of them on the trails I ride around here (PA, D&L Trail, Ironton Trail, Plainfield Trail, etc.). Everybody I’ve talked to really likes them.
I suggest you take a look at comfort bikes – something with the step-thru design rather than the boy’s bike / girl’s bike design. It’s a more comfortable riding position as we age, and we’re not concerned about getting the ultimate speed or endurance.
When it comes time to find a rack for the bike, be prepared for another round of sticker shock. You can get some pretty inexpensive strap-on racks, but be aware they will mess up the paint on your car by rubbing on the paint in the same spot all the time. Roof racks are pricey; keep in mind that the bike will always be faced with high wind, so the things need to be very sturdy.
Hitch racks are the way to go. Walmart sells a pretty cheap one, but don’t expect it to last very long.
No assembly; take it out of the box and put it on the hitch. It actually takes me 12 seconds to put the bike on the rack and be ready to drive off. It’s been on the car for six years and looks brand new. There are several YouTube reviews you can find. No ‘gotchas’, best online item I have ever bought.
I have more bikes than I know what to do with (seriously, there are 10 bikes in the garage and just two of us to ride them!). Mountain bikes, road bikes, a tandem, a fixie…about the only kinds of bikes I don’t have that I want are a cruiser, a cargo bike, or a 'bent. There’s a zillion different bikes out there, for all kinds of uses and needs. If I were in your shoes, I would pick up a few copies of Bicycling Magazine (coincidentally headquartered not that far from you) to get an idea what kind of riding really appeals to you and the bikes that’d make that riding most enjoyable. I would also hit up an LBS or two and get their opinions (but resist the upsell).
Once you have an idea what kind of bike you want, check out used deals near you. Sometimes the LBS has used bikes, and Craig’s List can be a great source as well. Like Turble recommends, avoid the 75-miler bikes at Walmart or Target. You’ll only regret wasting your dough on them, with nothing to show for it.
Gently used big box bikes do last a few years. The problem is wanting to upgrade components is more expensive than buying a proper bike in the first place. It all depends on what you see in your biking future.
A really great bike shop near Reading is SHIRKS, owned by a Mennonite fellow, caterers to both the plain crowd and the lycra and carbon graphite folks. He has lots of used bikes and does trades too.