A recurring subject.. bikes are always a good thing to have on board. Over the years we've been through 3 pairs of folding bikes, all Dahons. Started out with
the old 16" stainless steel folder. Looking for bigger bikes to cover more ground, for a couple of years, we had a couple of throw-away 24" Walmart bikes, where we removed the front wheels to put them away in the cockpit locker of our 31' Island Packet. After they crapped out (rust), and tired of breaking them down, we upgraded to folding 26" Dahon Matrix bikes. Great bikes, but when we crossed-over to the Nordic Tug, the 26" bike was too big to easily put down in the engine compartment. Picked up a pair of Dahon 20" Mariners, and that's the bike we currently carry.
Bikes are great to cover miles and to do some sight-seeing and shopping. Anchoring out most of the time, they can be a pain in the a.. to get to shore, but if we're going to be in one location for a couple of days or more, the bikes go to shore.
To this day, we still put the 35-year old 16" Dahons in the trunk of the car if we're going some place to take a bike ride, use the 26 inchers to putz around at home, and the 20 inchers on the boat. Of course, biking assumes your in reasonably good shape. We're in our 70's. We both had some medical issues (cancer, mitral valve repair), but not enough to stop biking. We will walk and carry a back pack if a round trip is about an hour or 2. For example, Great Salt Pond on Block Island to Town is a walk. South Lake to downtown Montauk is a walk (30 minutes). Plus, we discovered (wait for it)... BUSES and senior rates. A lot of places we cruise to have bus shuttles running all over the place. A couple of examples, Greenport to Riverhead to Montauk, and all around Martha's Vinyard. But if you can, bikes are the way to go.