Giraffe gearing

I’d assumed that apart from deliberately geared up penguins and similar that the gearing on giraffes had the same size chainrings and sprockets for a 1:1 ratio between cranks and wheel. But it seems not - at least in the case of the one I own. I marked the sprocket to get things realigned when removing the cranks to service the bearings, and then thought I’d got it wrong when the mark didn’t line up - it turns out my giraffe has 32T chainrings and 28T sprockets (it’s a Nimbus twin chain), for an effective wheel size of about 23".

Is this actually a common thing, or is my giraffe weird?

I don’t have a giraffe but having differing sized sprockets would make the tire wear more evenly than if they were 1:1. Weird or not it’s probably a good thing. has a 16" wheel kit for the 20" wheel, and those generally run a slightly larger ratio to make up for that. Got a pic?