In any case, here's the info in case someone else has the same question.
- HunnuAir takes a maximum of 2 bikes as luggage on the plane
- you can claim those 2 places by sending an email in advance to [email protected] (first come, first serve)
- they prefer the bikes without rigid packaging because of a small baggage hold
- they also asked us to ask our agent to note on our ticket that there are bicycles
Not sure what an agent is and if we have a paper ticket

Here is another, earlier answer from Dan at tomongolia.
The basic rules for domestic flights do not encourage bicycles.
The reason is the limited space for cargo in the plane, with priority for merchants and mail post packages.
Your options ordered by priority:
A. Once in Mongolia, visit HunnuAir office in UB, or at the airport cargo office.
B. Ask a local to call 7000-1111 (or international +976-70001111) this is HunnuAir special cargo desk, not all clerks speak English.
C. In Olgii come to the airport a day or two before your flight with your bikes packed properly, this is the general rule for oversize cargo.
D. In Olgii ask about cargo trucks or vans going to UB, they might have space for your bikes. They hang around the Olgii market.
E. Make sure you leave a few days free between your flight from Olgii and your international flight out.
If not, hire a local through your guesthouse to take care of your bikes once they arrive in UB,
make arrangements with your international airline to accept the bikes as part of your ticket and destination.
F. There are also cargo flights from UB to most major cities in the world, they will accept any size.
See this photo for proper packaging of bikes for flights
Dismount paddles and twist the steering handles, to make the fit in a box.
For cargo you pay by total box dimensions.