FCFB stem mtb bike road bike alloy + 3k carbon angle 6 stem road bike stem matt China Patent ZL 2013 20480319X road bike stem mountain bike stem This is a world-class OEM factory Shun Feng Technology Co., Ltd. Foundry size 70/80/90/100/110nn angle 6 fork diameter 28.6 mm , handlebar diameter 31.8mm weight 100mm 122g