The MWOD (Mr. Whirly Offset Double) system is a modified spider and ring combination for Mr. Whirly cranks, designed specifically for use on bikes running very large tires and rims, such as our Moonlander. Standard triple ring cranks can allow the chain to rub the rear tire when shifted into the lowest gears. On a bike made for crawling through the thick and sloppy or over insane terrain, these low gears are essential and cannot afford to be compromised.
To solve this problem, the MWOD system ditches the big ring. The outer (largest) chainring on a mountain triple is rarely used with extra wide tires. With the outer chainring removed, the granny and middle chainrings are shifted outboard to the old locations of the middle and outer chainrings. This shift effectively gains you around 7mm of tire clearance at the chain without increasing your Q-factor and without losing your crawling gears.
With the rise in popularity of so-called fat bikes, there now exist lots of tire, rim and frame options, creating a No-Mans-Land of mostly but not completely compatible combinations. While MWOD complete cranks are set up specifically for Moonlander frames (which are designed with lateral 28mm offset to provide clearance for 100mm rims and 4.7˝ tires), the MWOD system also works with other frame and wheel combos. Say you want to run 82mm rims on your Pugsley. The frame’s offset is designed around 65mm rims and 3.8˝ tires. Wider rims will place the tire closer to the chain in its lowest gear. If you’ve got a Mr. Whirly on your Pug, you can install the MWOD ring set and just like that you’ve got a bigger footprint and no chain-on-tire rub.
Get it? Got it? Go for a ride.