as for …, riding, getting on, being on, being placed on
→ の
のっto get on; to ride or take (a vehicle)+てTe-form (conjunctive form)
phraseCommon#5,038
as for …A conversational form of のは, used after a clause to make it the topic or emphasize it. It is often translated more naturally with phrasing like “was it … who,” “when was it that,” or “doing … is.”