I am actually using the motor(s) to power a chain-drive compost tumbler, not greenhouse rollup. The tumblers require a lot of torque, and these gearmotors do great! The low rpms and reversible direction are a plus for me. I ordered a custom small chain sprocket (20mm bore), and use a 9" sprocket gear mounted on top of flanged bearings. I looking for the best timer, which would allow testing of frequency, etc. Right now I am making a drum full of compost in just over two weeks, in a cool, dry alpine climate, at 7,000 ft. These are great motors!