In a previous post I compared and contrasted the Surly Pugsley and the Pug Ops. The Moonlander is Surly’s fattest fatbike with mammoth 4.8″ Surly Lou and Bud tires with 120t.p.i. (25% bigger than the Pugsley tires) on 100mm “Clown Shoe” rims. In order to make room for the fatter tires the Moonlander’s rear triangle is offset a little bit more than the Pugsley or the Pug Ops with a corresponding additional offset in the rear wheel. And the Surly Offset double crank gets a few more spacers so the chain won’t rub on the tire in the lowest gear.
You can see the 180mm brake rotor on the front of the Moonlander compared to the 160mm rotor on the Pugsley. A little more leverage to deal with the momentum of those taller, wider tires. The Pug Ops is spec’d with 180mm front rotors too.
The huge tires on 100 rims on the Moonlander can be ridden at very low air pressures for more flotation and traction on snow, sand, gravel and/or roots. Surly claims this bike is “designed from the ground up to ride where there are no roads, no trails and no people.” When the sandy single track gets wet in the Boise foothills two inch wide mountain bike tires dig in and cut up the trail, but the Moonlander barely leaves a mark! A bike like the Moonlander can expand the riding season as well as the areas and terrain that can be explored by the bicycle traveler. If you still think fat bikes are limited, look at this article in bikemag.com about the Walmart fat bike tearing it up at Sea Otter.