Since joining the grown-up cycling world about 9 or so years ago, a number of trends have come and gone, others have become fixtures. I've dabbled in hydraulic disc road bikes with internal cabling, 11-speed (then new), etc. It wasn't for me and still isn't, mostly because rim brake systems are much easier and overall cheaper. Di2 is neat though.
Now, the whole '80s bike thing came and went without me knowing it because I was born then, BUT the resurgence in 'vintage' bikes, what, 10-15 years ago(?), I got in on the tail end of and have definitely spent money and still spend money on that 'trend' even though most of the buying public has very much left it behind. Sigh. Hoping the overpricing (for what one gets) of many new bikes means the cheap/cheaper seats sellers like me get more action. I have...a few things to sell.
