
JT SPROCKETS Standard Steel Sprocket 239 - 420 (Manufacturer part number: JTR239.42) — a rear sprocket designed for replacement or adjustment of the gearing on light vehicles and small displacement bikes. Designed by JT Sprockets, it fits into both Urban and Cross environments, suitable for on-road and off-road use.
This sprocket is part of the final drive and mounts as a direct replacement for compatible references. The choice of C49 steel provides mechanical consistency suitable for the demands of the hub and chain; its machining respects the geometry of the teeth for regular contact with the 420 chain. Ideal for routine maintenance or gearing changes, it installs easily in a chain kit or as a standalone replacement.
Notable compatibilities: HONDA MBX 50 SD (AC05) 1987, HONDA MBX 80 FWD (HC04) 1985, HONDA MTX 80 (HD06) 1982. To maintain optimal lifespan, regularly check the chain tension, alignment, and condition of the teeth.