For those flying in/out of Canada, I’ve had a lot of good experiences with Air Canada. They allow you to check a bike as a regular piece of luggage up to 70lbs and I’ve never had trouble with them. Just call in advance to let them know if you have a bike if you’re going to a race where everyone else is bringing a bike.
As well, they tend to be good managing their partners - last year at Lahti 70.3 WC, Air Canada had saved me a spot on Air Scandinavia for my initial flight Helsinki → Copenhagen when the plane was clearly full of bikes and others were not able to get their bike on the plane coming home. I did call in advance to let Air Canada know that I’d be bringing a bike, and they made sure that there was a spot for me at each connection.