Originally Posted by FlashBazbo

For LandRun (actually more of a mud race than a gravel race) and Dirty Kanza, I think a bike needs clearance for 45mm tires plus mud. With that clearance, I use 38's (that measure out at about 41mm) -- because then you get even more mud clearance and can keep going when others are doing the hike-a-bike. I bought the Checkpoint because it advertised clearance for 45mm tires, plus mud. But . . . with a Di2 front derailleur on the bike, there's only clearance for 38mm (measured) wide tires and ZERO mud clearance at the derailleur. That 1mm gap between 38mm (measured) tires and the front derailleur appears, to me, to be a bad experience waiting to happen. My 35mm Gravel Kings will fit, but my preferred racing tire (Challenge Gravel Grinder 38mm) are up against the derailleur. [Trek has since reduced their clearance claims from 45mm plus mud, to 38mm, to 35mm, back to 38mm, and now 40mm but only with a specified Bontrager 40mm tire. My LBS is taking my Checkpoint back as soon as my Salsa Warbird frameset makes it to town.]