Ahem, I add slightly unrelated *int'l* bike transport tales, since many here are prepping to fly to Europe for PBP next year and might find helpfulmy experiences with UA and Air France when flying with a standard 700c 54cm bikes packed in cardboard bike boxes in 2015 and 2019.
The same boxes bike manufacturers use to ship bikes with the same packaging materials (free/cheap at your LBS and in Paris Bike Shops before return) worked well. **UA and Air France had/have different charges for bikes that fit into different size boxes, but reps of each/both companies interpret/enforce the rules...uniquely/sporadically/haphazardly...pick your adverb--prepare to pay whatever is stated as the extra charge for those two/any other airlines and you might be happily surprised when you're not charged a fee.
Longer story for those with more time+inclination:
In 2015, I flew into Gothenburg, Sweden 5 weeks prior to PBP and rode around not enough of Western Europe before my first attempt at PBP. I recommend something like that to anyone who can swing it in 2023. Gothenburg, in particular, is a lovely place, with a GREAT airport for cyclists to fly into/out of. In 2015, it was a super cheap destination. That is not true every year.
Cycle touring in Europe, as I feel certain many others with vastly more experience can relate in far greater detail, is SHEER H E A V E N. Touring, after having qualified for PBP, as a way to keep fit+avoid over-training AND to get your body onto the GMT+1 time zone completely reliably pre-PBP, AND, during France cycling km, to get one's digestive system accustomed to eating the foods you'll find on PBP...well, it's hard for me to imagine a more enjoyable way to spend the summer.
In Gothenburg's friendly, fairly small airport, kind baggage handlers gently delivered my bike to the oversized luggage area. I had ample space and time to assemble my perfectly transported touring bike, attach panniers and bags, then pedal into the city on quiet roads in a warm, steady, moderate rain that dissolved the route instructions I'd printed on paper. [I did not buy a handlebar bag with a plastic cover until I got to Paris and went to
Cycles Alex Singer. Make that rando pilgrimage to the
iconic shop just barely beyond the Périphérique that encircles Paris on Rue Victor Hugo 53 in Levallois. I never did figure out how to upload routes reliably into my Garmin 820 Edge...have never had any problems with the Wahoo Elmnt that replaced that computer in 2018] Luckily, road signs in a Germanic Language not entirely dissimilar to English + a non-horrible sense of direction combined with a friendly couple at one intersection to get me to my hostel shortly after the rain had cleared and a rainbow correctly forecasted a summer filled with joys.
... Post-PBP, I found a bike box at Cycles Laurent in the 10th arr. in Paris and packed my touring bike for the return. I added to that LARGE box ALL sorts of clothes, tools, helmet, etc that I just did not want to carry as I had before. I spent a week post-PBP unburdened by all but a change of clothes. My bike traveled home with a generous SFR couple who delivered it to a friend in SF. Here's the thing about the French: if you have patience, you can get ANYTHING you want in France. If you don't have patience...bonne chance! My bike box was WAY overweight since I over-packed it for the return on Air France in 2015. At the Paris CDG airport I thus had to lug that heavy box (on a cart) from baggage check to a special weigh-in area...and back to baggage check with a special sticker...long story just a tad longer: in all the back-forth, the AF agent charged me only the over-weight fee and not the de rigeur Bike/sports equipment fee (grrrr) for luggage.
2019: United Airlines SF-CDG-SF (aller-retour) charged their usual each-way extra bike box fee outbound but not inbound. Go figure. Again, I used a card board bike box from my LBS outbound. However, this time
Cycles Laurent--as did EVERY other bike shop in Paris!--had zero empty cardboard boxes. Not to beg, not to borrow, and, while I'd never ever do this, not for anyone else to steal. Paris had gone green. Recyclers picked up all cardboard regularly, including the day before I tried to pack my bike for the return. I had to, thus, RER to CDG the day before my flight, buy a super flimsy box for a nominal fee (€2?)...and bring that 4 pound but crazy-unwieldy flat rectangle back on RER and Métro to my friend's apt. and pack my bike for the next day's travel. This time, my bike was not overweight. I expected to be charged the fee on the return as I'd been charged outbound, but the agent at the gate liked to chat about whatever was on her mind and I let her and...well, she just never got around to charging me and I never got around to telling her she should and that was that.
Oh...in 2019 I toured other parts of Western Europe for a few weeks before PBP and had other adventures roughly equal in joy to those of 2015.
Go Ride Your Bike In Europe...everywhere you can, for as long as you can. You're welcome!