Originally Posted by
FrozenK
... so it isn't a patent issue.
It appears to be:
Chainring
EP 2602176 A1
ABSTRACT
A solitary chainring (50) of a bicycle front crankset for engaging a drive chain (10), including a plurality of teeth (52) formed about a periphery of the chainring (50), the plurality of teeth (52) consisting of an even number. The plurality of teeth (52) includes a first group of teeth (58) and a second group of teeth (60) arranged alternatingly between the first group of teeth (58). The first group of teeth (58) and the second group of teeth (60) are equal in number. Each of the first and second group of teeth (58, 60) include an outboard side (54) and an inboard (56) side opposite the outboard side (54) and each tooth of the first group of teeth (58) includes at least a first protrusion on the outboard side (54) thereof and each tooth of the second group of teeth (60) are free of the first protrusions on the outboard side (54) and the inboard side (56).
SRAM to license narrow/wide chainring design - BikeRadar