Despite these wheels being in the education kit, the retail kit and the education resource set, I don't see them used in many models. That could be because I don't get out much, or it could be that their slipperiness makes them less suitable than conventional gears. (I used them in pairs while building Alpha Rex, but the knobs kept disengaging from each other).
Knob wheels provide more surface contact than a regular gear, hence more torque (theoretically). But I haven't seen many around.
Can anyone point us to models on the web or in NXTlog that use these wheels? They look too good to just lie in the box.