Out of curiosity I've done some testing on some local paved hills to see how I would fair locked into 1 of my 21 gears. I was surprised to find that even at 70 gear inches I was able to climb some of them. But they are short, Longer ones would not be fun. 66 gear inches might be my choice to lock it in. That's 22 kph at 70 rpm. Mind you these aren't like the hills of a challenging soft gravel trail I ride at 30 gear inches. Hence the need for more then 1 gear, But not the 21 available, 8 or so of which are redundant.
I do like the simplicity of the single speed, But still want the option of a low and high gear. Enter the 3 speed internal hub, as used on a bike I had as a kid. I loved that bike. With the right sprocket we can have our cake and eat it too.
Bike gears are like car gears. The more you have, The greater potential for efficiency gains with respect to energy use and load limits, to a point. Three is much more efficient then one, and 7 properly spaced gears are considerably more efficient then three. At that point for those of us living in areas with low climbs, We gain little with 21+ gears.
What it comes down to is the increased complexity of multi speeds worth the higher cost (which is very low for entry level bikes) and extra maintenance and cleaning required. Most seem to think it is as 95%+ of the bikes Giant, the largest bike manufacturer in the world offers, use a derailleur type multi speed gear set.
Last edited by xroadcharlie; 02-05-21 at 05:03 PM.