PBI Sprockets Steel Alloy Honda Grom Front Sprocket PBI USA Countershaft Sprocket for the Honda Grom and many other Honda and Honda style engines is manufactured from Pro quality grade chromoly steel approaching 200,000 PSI yield. They are case hardened and finished with electroless nickel plating. A division of Chris Products, Made in USA! PBI Sprockets Honda Grom Front Sprockets are available in 13t, 14t, 15t, 16t and 17t options. The stock front sprocket size on the Honda Grom is 15 tooth. You can go down to 13t or 14t to increase your low end acceleration. If you go up to the 16t it will be slower to take off but with the potential for higher top speed, ideal for those with a big bore kit. A few rules of thumb with gear ratios for sprockets are as follows: Drop teeth on front/add teeth to rear = increased torque, increased acceleration, wheelies, racetracks with short straights Add tooth on front/reduce teeth on rear = increased top end speed, open road cruising, lowers RPMs, better gas mileage, tracks with long straights 1 down on the front is like adding 3 teeth on the rear The bigger the rear sprocket, the lower the gearing and the faster the acceleration Please click here to view our Gear Ratio Chart! Available in 13 Tooth, 14 Tooth, 15 Tooth, 16 Tooth & 17 Tooth CNC Machined from Pro Quality Grade Chromoly Steel with nearly 200,000 PSI Yield Case Hardened Heat Treated & Plated for Long Life & Extended Performance - Finished with Electroless Nickel Plating Fits #420 Chain Inner Diameter (peak to peak): 14mm Inner Diame ter (valley to valley): 17mm Thread Size: M6x1.00 A Division of Chris Products Made in USA!