Polo eBay finds/marketplace

I'm not sure if polo would put quite as much through the freewheel as trials so shouldn't be a problem

Reasonable assumption in the majority of cases.

maybe on the charge but I doubt it due the the massively high gear we use.

40" gear is generally considered low.

Lower ratio => More torque at the wheel, Less speed at the wheel

Someone linked to a Scottish bike "retail consultancy" which listed Soma, IRD etc in the brands offered. Spotted the IRD Defiant Single Freewheel (16T-18T). Cro-mo sprocket, £40ish

Couldn't find I emailed them yesterday (no reply yet) to ask whether they knew how many points of engagement it had.