Surly's OD cranks now have a more durable outer chainring option. Designed to handle snowy wet conditions that a fat bike using 
Surly''s OD crank might see the new 
OD Chainrings are made from 
stainless steel. The material change from alloy to stainless wasn''t the only update, 
Surly also revised the profile of the ramps, gates, and shift pins for better, more consistent shifting.
Surly has an 
OD Chainring replacement guide available online 
here.
- For Surly OD cranks
- Updated ramps, gates, and shift pins
- Direct replacement for older alloy OD chainrings