This question specifically applies to flying with bicycles. Some airlines (such as Etihad) are "bike-friendly" and allow inclusion of suitably packed bikes in the total allowance, others don't.
What happens on an international itinerary where the first leg is not operated by the issuing airline?
For instance a ticket issued by Etihad Airways has the following legs:
Houston - Dallas/Fort Worth: American Airlines
Dallas/Fort Worth - Abu Dhabi: Etihad
Abu Dhabi - New Delhi: Etihad
Even though Etihad is the significant carrier the passenger will check in at Houston with American Airlines.
Will American apply their baggage rules ($150 for the bike)?