I have a quick question i run a 14 tooth front 40tooth rear sprocket. My buddy has a 13tooth front and a 38 tooth on the rear i know bigger on front more top end smaller more low end but how does the rear sprocket effect low or top end thanks. what are the difference in these two set ups Thanks.

 

the rear sprocket is going to be the opposite of what the front sprocket does. the 14/40 is almost the same ratio as the 13/38. one tooth on the front sprocket is about the same as 3 teeth on the back.

if you keep the same on the front, and put 3 more teeth on the rear, you will have more low end, less top end, and will have the same effect as going with 1 less tooth on the front.