Our newspaper today had article about Delta eliminating their $150 extra fee for checked sporting equipment. Golf bags, surf boards, bicycles, scuba gear, other big items. American had just done the same (eliminated fees for those), and United had apparently already done so. All still charge regular bag fees, and the regular bag fee could apply to a sporting gear item. Or so read the newspaper.
Southwest allows two golf bags, scuba gear and small bicycle boxes without extra fees, but does charge $75 for larger bicycle boxes, surfboards, and some other large items. Still allows 2 bags without fees.
I've never flown with any of that stuff, so never thought about it. Once was in line with someone packing their fishing catch (big fish, iced down) and paying a pretty hefty fee which they had not anticipated. I think I was flying from Syracuse, can't recall the airline, long time ago.