Originally Posted by
cholly
Just picked up an old (1989/90) Schwinn 754 for very cheap.... needed some tweaks and updating, but a good ride. Compared to my 2021 Giant Contend AR, it's almost night and day smoother with much less vibration, with equal size tires and psi (25c/90ish). Both bikes are aluminum, Schwinn with a steel fork, Giant with carbon. Schwinn is several pounds heavier, but not looking to keep weight down, just a better ride.
With all the marvels of modern carbon, engineering, light and aero, etc. (so we're 'told')-- am I missing something? The Giant feels and sounds like a rattle trap compared to the Schwinn.
What you are missing is design goal of the bike designer. Some bikes were known to be stiff out of either aluminum or steel. Same can be said with aluminum. Carbon is no different. I have heard of people replacing 1in steel forks with carbon to get a stiffer, more precise fork.
Then, later on I hear of companies designing seatposts out of carbon to be flexible.
The reality is both can be true. A stock aluminum or steel fork from the 80s/90's could be more flexible then a nice carbon one. When I sit my big bum on a bike with lots of carbon seatpost at 27.2 bumps are damped. Isn't the same with most aluminum, and this can be attributed to wall thickness or tube design.
I have realized that the only way to tell is to ride the bike. I suspect many carbon bikes are harsh for racing, and use 32+mm tires to compensate. Obviously this is not all carbon bikes, but it's a great solution.
Man I kinda want one of those weird schwinn aluminum bikes. The quill seatpost is just neat.