Who's counting, but thanks.

I wasn't annoyed by the suggestion (not sure if you were referring to me), just explaining why I believe you don't find 3 speeds with the spacing you're looking for.

No I wasn't referring to you, and after 45 years in the bicycle industry, I'm aware of the market forces that drive which products are made available, and which aren't.

Sure, there are other things besides hub efficiency that matter more when it comes to overall efficiency. So what? Even as a commuter I want the most efficiency I can get in all areas down the line. Even little things add up.

My regular geared commuter is a 1x9. 42 x 12-26. The middle three gears get most of the use, so that's really all I need. Especially considering that I just as often do my commute on a SSFG.

A lightweight close ratio 3 speed hub with low drag would interest me. The present wide ratio units do not. Extra weight and drag for very little benefit in my situation. Obviously they fill the bill for some cyclists, and that's seriously great!

How feasible would it be to have a sun gear and planet gears custom made to adjust a hub's ratios? I know some machinists.

Not very. Not only do you need to cut the various gears, but you'd need to replace the planet cage since the center of the planets will change. Basically, you're building an entirely new hub. It would be easier to seek out an older or vintage hub.

Easier to find are older 5s hubs, which have the central 3 gears closer spaced than the classic AW. If you can find (and afford) a vintage hub there's the AM (looking for one myself) and the ultra close AC.

FWIW it's the AM's ratios of 87/100/116 that I'm suggesting are about right for GP urban/flat riders, vs. the typical 75/100/133 of most 3s hubs.

Making good gears is a specialty job but like threads, it can be done on convetional machine tools if you have the right accessories.

https://en.wikipedia.org/wiki/Gear_cutting

This is an excellent shortcut for a neighborhood machine shop

Spur Gears Stock

I'm not surprised to hear this, but I'm glad I asked anyway. Good point about the planet cage.

then you heat treat soft steel .. you need it soft to cut teeth then you harden it.

there is a just right temper.. too hard & it chips off teeth .. and cracks.. in use..

No problem. This has been developed and tested last year on a german touring forum and is now in production.

GEBLA

It would be possible to make a planetary hub with a closer ratio, but the 4:3 ratio is kinda optimal because the sun and planet gears are of equal diameter. Moving too far away from that ratio results in either a tiny sun, or tiny planet gears, that might not be as robust mechanically, or require a bigger ring gear.

Probably for this reason, the narrow range AC hub has two planetary mechanisms, which adds cost and complexity:

https://www.sturmey-archerheritage.co...s/pic-70.1.jpg

This is partly true, but can be overcome.

First of all, a 4:5, 5:6 or even 6:7 (which is just about what I'm looking for) wouldn't be that problematic, and shouldn't need two stages like an AC which is 12:13. (or close to that)

Issues relating to pinion size can be address by using a larger ring or compound planets, or both.

The issue isn't technical, it's economics and marketing. Tooling various hubs is expensive, and the aftermarket too small. For a mid range 3-5 speed single stage hub to happen would require a forward thinking OEM to market a purpose built urban/flat area bike using it.

Finally(?) Biggest influence on commute speed is fear of Losing your Job and starting Late, for one reason or another ..

That's a pretty tall order considering it's likely that urban/flat area utility riders would just spin their SS faster. Your target may be just sport/urban/flat area utility riders which would include me but is going to be a relatively small market.

If someone could design an efficient adjustable ratio gear system, that would be a different story.

Knowing I only have so much time to get someplace does tend to make me work a little harder.