Campagnolo manufactures two distinct eleven-speed inner chainrings that look similar but won't interchange between crankset generations. The 2015-current version uses a four-arm asymmetric spider with 112mm bolt circle diameter and threads into the back of the crankset through four bolt holes. The 2011-2014 version uses a five-arm spider where the outer ring bolts pass through and thread directly into the inner ring, which requires four threaded holes in the inner ring itself. You need to match the inner ring generation to your crankset generation because the mounting interfaces differ completely despite both being eleven-speed systems.

The rings use Campagnolo's X.P.S.S. tooth profiling that shapes each tooth to guide the chain during shifts. Campagnolo engineers the tooth profile, pin placement, and ramp angles as matched pairs between the inner and outer rings. The 34-tooth inner pairs with 50-tooth outer rings for compact gearing, while 39-tooth inners pair with 53-tooth outers for standard gearing. The 36-tooth option pairs with 52-tooth outers and provides a middle ground between compact and standard. You can't mix ring sizes from different pairs because the shift points won't align correctly and you'll get slow or inconsistent shifts under load.

Campagnolo applies their AFT anti-friction treatment to both generations. The treatment creates a matte grey finish that reduces friction between the chain and tooth surfaces while protecting the aluminum alloy from corrosion. Both inner ring generations fit Record, Super Record, and Chorus cranksets from their respective model years. Made in Italy.