I was unimpressed with the plastic Monster wheel from Sailrite. While it increased the torque it is light and feels kind flimsy compared to the original balance wheel, but the $130 for the aluminum version is not in the budget. I found a wheel designed by Testing321 on thingiverse, but it was aslso 100% plastic including the area that acts as a bushing, but it gave me the idea to create a adapter rather than a replacement. I used Testing321's design as a base as I liked the shape, but designed a two piece wheel that fits over the factory balance wheel and increases the size of the belt drive. I have yet to test the design I do not have a belt yet, but it fits tight and feels great. The photos are of a draft print. It bolts together with m4 x 20mm socket head allen screws threaded into the plastic (I don't think inserts are necessary). and I included voids for 8 10 x 20 mm stainless shelf pins if you what to add additional weight. I would consider adding extra walls to the gear portion of the design, and using a structure infill would be a good idea. The design prints wall with minimal tree supports.
I would think nylon would be the ideal material, but PLA should work as i wouldn't don't expect this part would get hot. Everything is designed to fit together tight! Assembly may require a little elbow grease
The author remixed this model.
The model borrows its grip design, and outer gear from another model. All other aspects including outer profile the inner gear interface with the factory balance wheel, 2 piece design etc. are original.