Stan's Crest MK4 Front Wheel - 29 15 x 110mm 6-Bolt BlackStans NoTubes Crest MK4 Front Wheel 29 15 x 110mm 6 Bolt Black. When youre looking for a lightweight Gravel and XC wheelset built to roll fast and last forever the aluminum Crest MK4 is your wheelset. 25mm rim width optimized for Gravel and XC tires up to 2. 3 Light and durable 6069 aluminum with welded joint and reinforced spoke bed BST Asymmetric design combines Stans legendary easy tubeless inflation with a stronger more balanced wheel build M