I mail them to my hotel.

Never traveled with a bike, but have with car seats in big bags/cases. Always free and agents never look inside. This may be unethical (and I'm not recommending it), but curious to know if anybody here has ever tried checking their bike as a "car seat"?

Agents can see right through that.

Mine stay in my seat bag. Most of the time they make it through, but every so often they don't.

Really? My kids are running around and climbing on the luggage scale and the agent takes our car seat case (which is exploding with all the extra shit we don't want to go through security and don't want to pay for in a real checked bag) faster than f*ck to get us out of there. No agent has ever looked twice at whatever bag/case we use for the car seat(s).

Telling an agent that your bike case is for car seats is pretty transparent.

I have done six races out of the country and never had to pay any sort of customs or duty. Sometimes I got asked specifics about why I’m traveling with a bike and how I’m planning to get the bike home. I found that by explaining that I’m bringing the bike into the country for a race and providing the name, date and location of the race has been enough for me to get the bike into a foreign country with no customs or duty payment.

I buy them at the race and give them away to locals afterwards. It is good karma and I have never flatted at an international event in 11 years of travelling with my bike. The cost is chicken shit compared to the airfare. Why take a chance with TSA when you certify at online check in that you are not bringing compressed gas with you?