These are very easy to use, once you get a little practice- even for me- a very small person. With a little practice, you can mount and dismount a bike from the rack in 10 seconds or so. When the bus pulls up to the stop, I hold the bike up in one hand and keep the other free to lift up the latch that frees the rack to be lowered. I pull the rack down with that hand, then lift the bike up and secure it. Same thing in reverse when unloading the bike. The inner racks require more of a reach, but even I manage with my short arms.

Bikes with fenders work fine. You can either put the rack arm over the top of the fender or under it, depending on how much clearance there is between the tire and the fender. I don't own a 29er, though, so I don't know if one of those can be used on a bus rack.

Most people remove panniers from their bike before putting it on the rack, and some transit agencies may require this. I carry my gear in a backpack, as it makes the bike easier to lift and makes it easier for other bikes to be mounted on the rack next to mine. It also helps the near-field view of the bus driver if panniers aren't in the way.

For extra security, I use an extra bungee cord to secure my bike on the rack. I run it from the chainstay crossmember just below the seat down to one of the rack tubes by the wheel tray. It isn't really needed, but it's an extra bit of peace of mind. None of the drivers have ever objected.