Our premium 2X Cannondale Hollowgram compatible direct mount Oval chainrings are designed for Hollowgram crank family like SI, SISL, SISL2. Incredibly stiff and light. Super fast shifting thanks to our patented shifting ramp design. Sold as set only. Chainrings use proprietary bcd mounting system, therefore they are sold as sets of 50/34 or 52/36T combination only. Size (Mass +/-1g): - 50/34T (184g), 52/36T - (188g) Color - Black Compatibility - Cannondale Hollowgram Si, SiSL, SiSL2. chain: 10, 11spd Material - cnc machined 7075 Txxx Aluminum. Long-lasting construction Finish - anodized Chainline - Same as original spidering. Ovality - Optimized to each size separately. 34T- 6.5% ; 36T- 11.4%, 50/52T - 10-11.2% ; Timing of 108 -110.5° after TDC (top dead center) - Ideal for road climbing. Patent Pending ADVANTAGES OF OUR SPECIAL DIRECT MOUNT CHAINRINGS: *Finest design to provide excellent weight to strength ratio *One of a kind special oval shape (Patent Pending) *They save weight because they don't need the spider and chainring bolts. *Superb quality and great look. *You will ride faster using ovals. *You will not "feel" the oval shape at all *Reduces stress on knees *We mastered our oval chainrings to perfection, so you can get best possible advantage from the oval/elliptical shape. HOW TO MOUNT DIRECT MOUNT CANNONDALE OVAL CHAINRING: Remove crank from the bike. Open the lockring with "Cannondale Hollowgram Spider Removal Tool KT012". Remove original chainring/spider.Generously grease the waved interface of the crank arm, then place new spider chainring same way as original one. Apply small amount of medium strength Loctite on the lockring threads and tighten it with torque of about 47-54 Nm. You will need "Cannondale Hollowgram Spider Removal Tool KT012" or similar to open and close the lockring. Designed in UK. Manufactured in Poland (EU).