>>1726001something that fits you and the terrain that you will be riding, local listings and stuff like that can be good for a first bike but its nice to have someone check it over who knows so ur not buying junk. generally any road bike or hybrid or 90s mtb is great. avoid second hand carbon ( this includes forks) on bikes. Heres' my latest criegslist steal that I use for just a beater, I love this thing and it would be a great beginner bike. for me it has all the checkmarks of no weird proprietary shit, rim brakes, steel frame (alloy is fine too) and road geometry. Only thing I would want on this bike is bigger tire clearance but 26's are fine for me desu. if you find a bike that more or less looks like this its prolly an ok first bike. I got it for 100 dollars flat