A nicer bike that fits you well is a real treat. I did find that in my 50’s I developed a bit of neck and shoulder pain. I sought out road and touring bikes that (1) put the handlebars above the saddle and (2) had room for fatter, more supple tires. I also gave up drop bars for more mustache-style bars which enable a lowered position as well as a more upright one. There are lots of niche bikes to check out these days. My Rivendell is more of a light touring/road bike. My sister in law recently bought an adventure bike which gave her room for slightly wider tires and also more standover. You may want to also look at cyclocross bikes which are racey but also a little more upright than an aggressive road bike. Any of these bikes might remain more comfortable as you move through your 50’s and beyond.

john