What gearing for a single speed pulling a trailer?
 

Pure theorizing here. But IF converting my old steel mtb 26er to 700c single speed (easily done) AND pulling my </= 100 lb trailer up to (let's say) 10 percent hills, what gearing would work best? At my current conditioning level, I have pulled 14 percent hills with a former steel single speed at a 2.0 ratio, sans trailer. With an aluminum single speed at 3.0 ratio, I'm not able to conquer 14 percenters. With a geared, steel mtb (and trailer) struggled on the same hill (but made it) at a 1.0 ratio, easier with 0.8 ratio.

I did experiment with steel single speed (without trailer) and found 1.75 ratio, or less, is a spin out on FLAT terrain. However, 2.0 is ok for coasting downhill (even with trailer) if seemingly taking quantitatively longer to reach a destination.

Seems I've almost talked my way into a solution. So, what would ya'll suggest (between 2.0 and 3.0) as a reasonable ratio. And, as an after thought, is there any disadvantage to pulling a trailer with a 700c/32 spoke as opposed to a 700c/36 spoke? Are there other things to consider?

Why? I love single speeds and fixed gears but why pull a 100lb trailer that seems miserable? If I had a geared bike that could pull the trailer I wouldn't swap that to a single speed I would use that bike for pulling the trailer and maybe lower the gearing on that or put one of those wide range 2x or 1x setups on it.

I have 1 fixed gear and another bike set up as single speed and have a desire to build a custom fixed gear road bike (meaning a custom frame to my geo not an off the peg frame like my other stuff) but I also know I don't want to pull weight on it I have other bikes for that including a touring bike and a hybrid as well as electric bikes should I want to make it easier. I have zero desire to make my job harder especially with 100lbs.

For example: Any number of economic situations could result in the need to go as austere as possible. Idly thinking about it is better than immediately needing to think about it. If no one has a positive thought about it, then this thread can calmly die. No worries. :)

Yes it would be one thing if your bike was already single speed then it would be a different story but you have a geared bike and a single speed if memory serves. Use the geared bike for trailering and the single speed for whatever else you want.

Or do what one guy on Bike Forums often mentions he does and carry spare cogs, a lockring wrench, and a chain whip. He says that he routinely changes sprockets several times during any hilly ride. I guess the rear fork ends are long enough to obviate the need to carry a chain tool to lengthen or shorten the chain.

I think that is 79pmooney if not mistaken. I remember watching a video from Look I believe or Mavic of someone who did a ride in the Alps a ridiculous mileage (or kilometerage) who basically did the same (or at least had a flip flop hub) but he wasn't carrying a 100lb trailer and I don't think 79PM is doing that either.