I’m curious if a used bike is ever too old. I want to get a new bike this year and I’m on a pretty small budget. If I go new I will probably get a Giant contend 1. Mostly sora components and a carbon fork so a bit better than current bike. The used bikes I’m seeing in my size all seem pretty old. For instance there is a 2011 carbon bike with updated ultegra 11 speed which sounds great. But when I read about used bikes I always read that carbon can hide flaws well and this bike probably has lots of miles. And I always read aluminum can fatigue with lots of miles. So should I stay away from bikes over a certain age? Will the new bike be more reliable even with much lower grade components?

Old bikes will be fine. Don't worry about it.

For a new bike, unless you are going to get a super light carbon bike, don't overlook the new aluminum bikes. Some are under 18.5 pounds and you will be able to get a better component group. Tiagra for certain, maybe even 105. Not an SRAM user, so I don't know if options open for it's component lines.

Old bikes are good. I ride a 27 year old bike and 39 year old bike that I put new components on. It didn't save me much money if any by upgrading them, but I get what I want out of it.

edit:
oh.... never mind, you said "carbon fork", not carbon bike. So half my post definitely does not apply.

FWIW my bike was among the best top level frames made 11 years ago, and I got it for the price of some of the bottom level frames made today