We were thinking of a "pseudo 2 speed gearbox". By that, I mean we'll be using a single speed CIMple box geared for high speed, but add a button to drastically decrease our speed. We don't think we'll need a lot of torque primarily from the gearbox itself, and we doubt we'll get into any (major) pushing matches, so we think the wheels we're using and the "low speed" button we have will solve those problems.