BLACKSPIRE ARE ONE of several companies producing single chainrings inspired by SRAM's outwardly simple but actually super-cunning and extremely effective chain-retaining alternating narrow-wide tooth design.
Despite Canadian machined manufacture it's 35$ to 50$ cheaper than
official SRAM spares, with prices ranging from 40$ to 75$ depending on size. It
holds the chain securely without obvious extra noise or drag, and wear life is
good. This 30t version is offset inboard to clear the crank spider, and bolt
receivers are machined into the ring to simplify tightening. Green, red and
blue anodised versions are also available.
PRICE 65$ (30t/104mm BCD)