165mm cranks have been sold out or on back order for ages. Has everyone been moving to 165mm length cranks? Is there a fad or some recent sport science that came out showing clear benefit of 165? Or is it just the upcoming Tour de France and Olympics that teams are hoarding them? Just a few thoughts I've had.
This is the "pogacar effect". Everybody wants shorter cranks now.
In my case 165 for road bike feels more natural, is great for cadence, without thinking i gain between 5 and 10 rpm, a bit easier to accelerate and put immediate power.
For me it's another way to pedal and produce power with more cadence so less torque to apply.
On mtb i will probably stick to 170 because it's harder to just sit and pedal 90-100 rpm, but i'm probably sure i won't go back bigger crank arms.