This is a replacement for the standard Strida folding bicycle belt wheel ("chain ring"). It fits to a standard 130 mm bolt circle crank spider. (The one in the photos is from Lasco -- it's available on Amazon. This belt wheel is designed to work with a standard 8 mm pitch, 12 mm width HTD or GT2 belt. The belt wheel has 100 teeth, like the standard Strida belt wheel.? ?
The belt wheel in the photos was printed in "White Strong & flexible." I "painted" it black with a Scripto marker!
(The photos show the belt wheel installed on my recumbent bike, not a Strida!)