We have noticed some people travelling with just one gear, but if you want to have a less painful trip (and avoid pushing your bike up hills), you should be sure to have at least some light gears. Maybe you want to take a look at the topography of the region where you are planning to join the biketour and think about whether you want to take a bicycle with racing, touring or mountainbike gears. Remember that there are always hilly parts as well!
