Aluminum bikes have always been harsh, the old Cannondales for example, but they were
cheap and therefore easily replaced if you crashed in a criterium.
Steel was of course heavy, but still a very excellent material, a good Columbus
steel bike with brazed investment cast lugs is still sort of the gold standard for many.
Titanium is I believe the best frame set, but due to cost to manufacture you just don’t see it anymore, Carbon Fiber offers most of the advantages, at a fraction of the cost. Carbon fiber is actually not expensive, Titanium isn’t really either, it’s the machining and hand welding required that makes Ti not
cheap.
The big disadvantage of carbon fiber is it’s easily damaged, and if it’s an expensive lightweight frame set, it won’t tolerate much damage at all, and Carbon Fiber has a nasty habit of being just fine and then one millisecond later it completely fails. I wouldn’t put an expensive Carbon Fiber frame on a
boat myself, something would damage it I’m afraid.
If I were wanting an honest to goodness good
boat bike because I was still a bicyclist, I’d talk to the folks at Bike Friday be measured and have them build me a custom bike.
But I’m not so my inexpensive run of the mill aluminum Dahon will have to do.