What are gear ratios

Hey Everyone, I have the XR650R service manual and was looking through it hoping to find the gear ratios for each of the gears so I can figure the gear ratio with different front and rear sprocket combinations? Any one know of any specs or know where i can find them? The manual does say the number of teeth on each of the gears but there is one for each the countershaft(C1-C5) and mainshaft (M1-M5) but doesn't list the teeth on the counter shaft or the mainshaft so I can't make heads nor tails from all this? Can anyone help me?



I found a gear ratio calculating spreadsheet on the Yahoo XR650R group that outputs ratios and min/max speeds in each gear. It adjusts for sprocket ratio as well as rear wheel diameter and tire size. It is in the files section; called gearing calc.xls.

Thanks XR250rdr, actually I found that excel spreadsheet before I posted this and noticed that the sprocket sizes and rear tire sizes were not the same for the BRP so I thought it may be a universal sheet that one had to enter the correct info for their own bike. My goal for this post was so I could re-enter the numbers that I knew worked for the BRP so I could apply it to mine! By the way I got a post from the fellow from the UK that posted the Gear Calc Excel Spreadsheet and he varified that he entered all info based on his UK XR650R and that as far has he knew the transmission was the same as the US version.

Thanks for your time and post


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