21歯ローラーチェーン スプロケット Bタイプ 硬化歯 25チェーン シグルストランド 1/4インチピッチ 12mm ボアブラック酸化物C45炭素鋼 04Cチェーン用固定ネジ付き

I keep buying this brand and type of roller chain sprocket because they are rugged, remain in place even under a heavy load, and how little sign of wear over time. If drilling the mounting hole out bigger, be sure to use a M5-0.8 tap to clear the grub (set) screw holes.

10 mm shaft inner diameter, great fit on my flip sky 7070 motor!

Starts off fine then after use it begins to skip, may have to have someone tack weld at this point due to having used the item.

As described, good sprocket

The bore size is actually about 1mm larger than advertised so when tightening down the set screws, the gear twists on the shaft making the sprocket wobble when it spins and therefore unusable.