Study the calculator
Warning: this is all math for me on the Silvio platform, the bike was just built and sits on the trainer waiting for spring thaw. I going off the theory that it climbs similr to a DF in most cases.
With that disclaimer: My thought is 22 is pretty low on a two wheeler. I have had such gearing on a DF in the past and never really used them, any time I need that low a gear pedaling it would flip the bike into a wheely. I live in very hill terrain with lots of shorts steeps. To leave my house I have to do ~1000 ft of climbing to get into the surrounding country.
I used the Mike Sherman calculator to build my gearing setup. In my case from experience, if I drop below 30 rpm on an incline I'm likely into the cannot push the gears any further due to a lack of strength and must down shift or get off and walk. So I setup my desired stall speed to be around 2.5 mph at 30 rpm and then line up my gearing with that in mind. Getting easier RPM at that point does not help me if I go slower and tip over.
So in my case I wound up with 29.5-125 GI, that gives me a gear that runs out at my stall speed for steep climb. But a nice tall gear that allows for slow pedaling going down hill without inducing pedal steer. I built my front on a double running 36/52 which shifts like butter, but it is a 110 BCD. If I am wrong and that is t0o big; I can switch to 52/34 which would yield 27.9-125
To go lower I would need a mountain bike 104 or 74 BCD or a triple with more complexity, weight and shifting fiddling.
The key to doing the setup math this way is to know that absolute slowest you can usually pedal under stain before you have to down shift. For me it is 30rpm. My wife struggle below 40rpm. Each person is different. For me my power mash under load is 60rpm beyond that it is not fun really going lower due to strain so I avoid it for all but short bursts. So at the lowest gearing at that RPM that gives me 5.6mph comfort climbing speed. If I encounter hills that I go slower than that on; I basically route around them in the future I really do not want to craw up a hill intentionally. But since we always hit that surprise hill when exploring, I have room to go down to 30rpm to get up and over them that one time they surprised me.
One nerds approach to hills. In 30 days or so I can actually tell you if this translated well to the Silvio platfrom or if I had to rethink my long standing approach.
Here's the link to the
Gearing tool
(I may someday make it a 52/39/24, but we'll see).
