OK, made a small change today that has made quite a big diference!
I swapped out the 13t drive freewheel for the 16t. That dropped my secondary drive reduction from 4.07:1 to 3.31:1 (13t / 53t is now 16t / 53t). This has had several impacts:
1) Loss of torque. This is a good thing, there's less wheelie danger. This is a commuter bike, not built for thrills.
2) Higher top end speed. Nice. This is subjective, I don't have a speedometer installed yet.
3) Less friction. I can feel a noticeable reduction in drag when pedal only performance.
4) Less noise in the freewheeling chain. I like that.
Also, moving from an odd number of FW teeth to even means loss of 1/2 link of chain. That's a good thing, the chain line is almost tight enough to run without a tensioner at all. I'm leaving the tensioner in the loop for now, when I'm in a better position to do testing I'll try without the tensioner.
Here the two FWs look the same
But this picture shows the reality - there's definitely a difference.
1st build: Dahon Jetstream folding bike
. Quick, reliable, capable of 30mph. Light enough to lift, folds for easy transport by car/bus/train.2nd build: RC powered 2009 Norco A-Line
. Top speed 31mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.3rd build (just started): Scratch build
ultimate utility bike.