I have an old Rudge, which used to all have 7 1/8 ... 182 mm. My old Raleigh 5 spd had gutless 165s.
4 Years ago I got a SA 5w and first used it 3 times with those 165s. Then I got a new crank with 180s. Instantly had the 9% more power, especially up hills. I can still wiz it up, which is the best way for speed. I am just 5' 8". Went 4200 miles on tour with it and a Rohloff.

With a derailler it is just lost in the gearing. 165 does now feel knuckle toed by comparison.