I've decided to buy the Trek FX 7.6 as I begin my adventure back on a bike. After the bike there are other considerations: tires, seats, pedals, a pump, computer, helmet and clothing. I'm seventy-one. I'm not interested in PRs or competition. Perhaps when I was in my thirties and forties, but I'm in this for the enjoyment and fitness.
Good choice. There are others, some cheaper and some more expensive, but if the 7.6 has the features, ride and component quality, and most important, fit you are looking for, who are we to second guess your decision?
Just which accessories and gear are 'good enough?' What benefit or advantage are pedals with clip-ons? When are they helpful to use if I never ride over twenty miles or so at a time?
Do you mean clipless or toe clips? If you mean clipless, they are helpful for just about any ride over 3 or 4 miles.
Tires. I see widths all over the place. I understand a wider tire will give a wider surface patch.The FX 7.6 seems pretty thin so I asked the LBS about swapping out the originals for, say 32mm. Would that size be good for the type riding we've discussed?
The 7.6 comes with 25 mm tires, which is narrow, but not super narrow. You could try those and see how you like them. 28 mm is a nice compromise between comfort, durability and speed, as is 32. It all depends on you, and the type of riding you do. If you have lots of broken up pavement and or road debris on your preferred routes, a slightly wider tire may be slightly more durable and/or comfortable, at the expense of speed.
Seats, there are so many different brands and types. I gather that each person's posterior is unique. Like shoes, I figure that you have to find one which will work best. However, where do you start?
How about with the stock saddle? Or just get a Brooks B17 to take you into your golden years.
I assume the pump helmet and clothing are individual preferences which will fill the bill as long as you buy a reasonably priced item and not shoot for the bottom.
Yes.
Computer...really? I use a Smasung Galaxy S3 which has a data plan. I have Copilot which reads the GPS receiver and has a built-in map to display my location. I also use Google's My Tracks which plots out the path on a map and stores speed, average speed, distance and elevation for each route. (I actually use that one for photography uploading the track into Lightroom) I know about the drain on the phone to perform these functions but I have an external backup battery which has over two full charges capacity. Will this be sufficient?
It may be, though my experience with iphone is that these mapping apps suck power, which might not be such a good thing if you need your phone in the unlikely event of an emergency. Basic wired bike computers are pretty cheap these days and last for years.