Converts any 8-9sp HG splined cassette hub to a single speed
GU-1809: Micro 1er compact single speed conversion includes 12 and 13 tooth deep tooth CrMo steel 3/32" cogs, (1) 14mm spacer, (1) 19mm spacer and a lockring
GU 1810: original 1er single speed conversion includes 16 and 18 tooth deep tooth CrMo steel 3/32" cogs, (1) 14mm spacer, (1) 19mm spacer and a lockring