Donnelly BOS Tubular Cyclocross Tire

American cyclocross grew up in Boston (thus, "BOS") and gave us some of the worst weather and hardest race courses, packed with mud, rain, slippery roots, and rutted out corners. 

When you tackle those conditions, pack the Donnelly BOS with your gear. It features buttressed side knobs to provide traction in slippery corners and a center tread that bites in for traction while you're struggling for grip on the uphill or for braking power on the descents. 

• 700x33
• claimed 376 grams
• Donnelly's unique tubeless design means the casing is airtight; no inner tube can be punctured
• Comes out of the box with rubber-coated sidewalls to keep out wet and grit, so no aquaseal-type add-on coating is needed, saving you time
• Removable valve core allows you to easily add extenders to run these on deep carbon tubular rims, or to inject sealant using the Caffelatex Injector.

TECH NOTE: this is a tubular bicycle tire (also called a "sew-up".) It must be glued or taped onto a tubular rim for safe use. It will not work on a traditional clincher wheel/rim. Proper setup is essential for your safety - if you are not qualified to install tubular tires, please seek expert guidance first.