LeeG

Weight lifting takes seconds, bike riding takes hours. So restrain yourself from doing the equivalent of climbing two steps at a time or leg lifts on a bicycle. If you try and turn cycling into weight lifting you're just as likely to develop an over-use injury just as if you tried to lift too much weight. Look at the folks doing spin classes, that's what you're going to do, although maybe not that fast.
I assume you're looking at used bikes from the Craigslist ad, you have to determine what the proper seat height position should be so look that up and go from there what bikes would fit ok. My suggestion would be to get some toe clips or clipless pedals but there are folks who ride those distances without them.
Biggest concern would be to not push to hard going up hill and not ride the brakes or go out of control downhill. Those are some amazing descents and it would be a shame to discover that you really aren't prepared to ride a bike at 40mph down a hill safely and there's some loose gravel or sand around a turn.
The trick is to not push too hard. The mtn. doesn't care if you blow up, fall over and turn into a dried up husk so you might as well learn to go slow at the bottom of the mtn so you have energy to crack jokes at the top.

Carbonfiberboy 

You want an ordinary modern road bike with a triple. The "46/36/26" is the tooth count on the chainrings, which are attached to the crankset which is the business with the pedals on it. "Triple" means that there are three chainrings up front, on the crankset. The cogs on the rear wheel are called the cassette.

The tooth count on any ordinary road triple will be either 52/42/30 or 52/39/30. Either one would be fine. Except that in your case, replace the 30T (T=tooth) chainring with a 26T Salsa chainring. That will give you lower gears.

The cassette is easily replaceable. Many different cassettes might work for you. I'm building a new climbing bike with that chainring configuration and a 12-25 cassette. That might be a little big for you, but 12-34 might be too small. You'll just have to try it out.

misagro

Thanks, I am going to take it easy, I don't want to be a dried up husk either! I want to enjoy the scenery. I remember going down the biggest hill you could find at full speed as a child then screeching to a halt before going into traffic. Don't want to try that on a mountain at 40mph!

FlatSix911

Lot's of useful advice so far ... Based on your type of ride and budget...
I would suggest a entry level road bike with a triple ring crank in front and full range cassette in the back

Take a look on line for good values with no shipping fee or sales tax.

Shimano Tiagra/Deore, 27 Speed 2010 Windsor Tourist $599
Custom butted 4130 Cro-Moly Frame & Fork + Rear Rack, Touring Tires
Cassette/SRAM 9-speed, 11-32T
Touring Triple Road, 30/42/52T

https://www.bikesdirect.com/products/windsor/tourist.htm

acantor

When the discussion turns to appropriate gearing for climbing steep hills, opinions vary. A lot.

Age might factor into it. I'm 54. My gearing needs are different now than when I was 24, despite that in some ways I am in better shape now. But it's hard to escape the effects of the second law of thermodynamics!

My opinion: There is no such thing as a gear that is too low when climbing for hours at a time. Hell, never mind hours. 10 minutes climbing a 12% grade against the wind is hard, hard work!

My lowest gear currently is 22T in front, and 34T in back. It gets me up almost everything, but it was not low enough to handle the 18% grade I encountered a couple of years ago. I have zero trouble staying upright or balanced in this gear.

If I were to get another touring bike, I would try to get a 20T in front and 36T in the back.