I was trying to add bicycle racks as a feature on a map, but it didn’t show up when I searched. Am I missing something or are they just not available?
Hi. I found it under ‘Bicycle Parking’. 
Yep, there are over 300k of them mapped so far (and there are loads more places to park a bike than a rack, so the name is appropriate, even if there are racks inside). See https://taginfo.openstreetmap.org/keys/bicycle_parking#values