Advice regarding Biking the Dingle Peninula Loop at 67, well worn versions of our original selves

Certainly not crazy If you are still comfortable on a bike. It does require a certain level of fitness to ride the whole loop. I did it and on my 50th birthday, and I would happily do it again twenty years later, but I work out regularly.

The bikes we rented were hybrids, not road bikes with dropped handlebars nor true mountain bikes with shocks. They were comfortable and light enough to pedal uphill, although not as light as my own Cannondale.

These days they might even rent e-bikes which do not require much fitness. Maybe someone knows about that?

At any rate, it makes for a lovely day (if the weather cooperates) and I highly recommend it!

Wow! There are several ways to respond to that question. The simple answer is "absolutely not!" Bottom line: Anyone who's healthy (that is, not violating the doctor's orders due to some serious medical condition) and not adverse to physical exercise can - and probably should - ride a bike. And for as far and as long as he or she likes.

In my experience, there's no simpler, better or more fun way to preserve and/or restore health and fitness - while exploring other countries at the same time - than by cycling. It's a gentle, ride-at-your-own-pace activity that has great benefits for your muscles, flexibility, bones and circulatory and respiratory systems - not to mention your spirit, overall sense of well-being and appetite! Like an army, cyclists travel on their stomachs!

So if your husband's physician gives him the green light, then don't let the opportunity pass you by. If you plan to ride more than 15-20 miles a day, then by all means ride touring bikes with dropped handlebars.

If you have questions about cycling in Ireland or the Dingle Peninsula, then send me a PM. I've toured by bike all over Ireland (including the Dingle) and Northern Ireland nine times now and have been seeing the world by bike for over forty years. Warning: It's addictive. And your family may begin asking, "Now just where are they off to now?!"

"Am I crazy?"
Don't know about the crazy, but misguided? Yes.
If you were already avid and regular cyclists I'd agree that you should give it a go. Since you're not I'd really advise against it. The ride around Slea Head Drive and finishing the loop by returning via the Gallarus Oratory is probably in the neighborhood of 25-30 miles, and while it's mostly level you can count on challenging winds and probably a shower or two during the several hours it would take you just to do the ride, plus the time for stops along the way. Also, the road around Slea Head is pretty narrow in places, ie not particularly bicycle friendly, so you'd be dealing with that too. Add the fact that after 5 or 6 hours in the saddle you'll be comprehensively miserable ... even with padded cycling shorts ... and you have the makings of a very unhappy experience.
If you really want to cycle an alternative would be to check out the bikes for a much shorter (and much more manageable) excursion on some of the less traveled back roads on the Dingle peninsula. There are probably local companies that cater to just that sort of thing, and with guided tours to match any level of fitness.
I really recommend driving the peninsula and saving the bikes for shorter excursions on roads less traveled.

Robert,

All of Ireland's back roads are narrow - as well as a little bumpier than in the North. Irish drivers are the most patient, courteous and respectful I've encountered anywhere in the world. Rain and wind are facts of life there (especially on the west coast) - and in many other places around the globe - but far from being prohibitive, or even discouraging, factors. And biking any distance does not necessarily translate into sore behinds, a condition I've rarely, if ever, experienced. If so, it was forgotten about thirty minutes after calling it a day. Twenty-five or thirty miles on a bike in one day may, to some, sound like a lot. In reality, though, it's much easier than the brain allows us to think it is.

I'm giving the OPs credit for knowing what cycling entails and faith for knowing how to prepare for it from having done so - perhaps extensively - in prior years.

If your experience bicycling in Ireland or elsewhere has been significantly different, please share that with us.

Zagfam,
I suggest taking a look at the street view feature on Google maps to preview the route. Might help to have seen stretches of the road for yourself from the drivers perspective before setting out, whether it be by car or bicycle. If you decide to give it a go by bike I'd also highly recommend doing some training rides at home to prepare yourselves ... and invest in a good pair of padded cycling shorts (you can thank me later).
Safe travels

This place offers electric bikes, gets rave reviews on Trip Advisor, and will deliver and collect the bikes to/from your accommodation. http://www.dinglebikes.com/
Might be an intriguing alternative to relying exclusively on pedal power.