bulebule Improve rim and motor mount

Maybe a 2-piece reel:

One to put the bearings in and to stick the gear to as well. Maybe a cylinder is a good approach (bearings in, gear out). Maybe it could be made of a little flexible material (to easily fit the bearings, the gear and the second part of the reel).
Another for the actual reel, which surrounds the first one and which holds the tire.

Take this opportunity to change to Mini-Z MZW2-20 tires (which are flat on the inner side).

Also, have a look at cheaper gears (i.e.: 70-teeth plastic gears).

Maybe use flanged bearings too?

See:

http://www.micromouseonline.com/2012/05/24/printed-wheels-complete-decimus-mechanicals/
http://www.micromouseonline.com/2008/01/10/wheel-assemblies-for-decimus-2/
http://maimaimouse.blog.fc2.com/blog-entry-46.html