Komentaryo sa Levitico 15:9: Rashi, Ibn Ezra, Siftei Chakhamim & Rav Hirsch

וכל המרכב AND ANYTHING FOR RIDING — even though he has not sat upon it when riding, e. g. the hold in front of the saddle, which is called arcon in old French, becomes unclean as a part of something for riding on (משום מרכב), and the אוכף, saddle, which is called alves in old French, is unclean as being something to sit upon (משום מושב) (Eruvin 27a).

any riding seat Provided that, in the opinion of the Exegetes, it can acquire ritual impurity

Even if he had not sat. Meaning: He does not actually sit on it, which would be sitting mentioned in the verse (6). Rather, [this refers to] the side of the saddle, which is the wood in the front and back of the saddle that he does not sit upon, but rather the rider holds onto it so he will not slip forwards or backwards. Therefore, it is called the ‘hold,’ since he holds onto it.