I have a passable understanding of how the chains and sprockets work, however how does the tuning of different sizes work?
I am assuming that I could put a bigger sprocket on just the front or the back and accomplish pretty much the same thing. A smaller sprocket at either or both ends would increase acceleration right? And a larger sprocket at either or both ends would increase top speed correct?
so would one tooth bigger on both front and back be a noticeable change in top speed?
conversely, would one tooth smaller on the front and back be a noticeable change in acceleration speeds?
What matters is the ratio of teeth on the front sprocket vs. the number of teeth on the rear sprocket. Think about how the sprockets work on a ten speed bicycle.
If you put a bigger sprocket on the rear and keep the front one the same size, you gear it down (increase acceleration.) If you put a bigger sprocket on the front and keep the rear one the same size, you gear it up (increase top speed.) If you increase the size of both sprockets proportionally you don't change the ratio.
There are other factors to consider - you can only make a sprocket so small before it stresses the chain by having too tight a circle, and you can only make a sprocket so big before it doesn't fit the motorcycle. Also, if you're going for top speed you're limited by the engine power; you could theoretically gear a Honda 50 so it would go 200mph but you couldn't actually make it go that fast.
oh yeah. I knew there was a reason I wasn't a mechanical engineer.
Obviously if the increase in size is equal to both sprockets, then no change will occur.
Thanks for the facepalm moment.
Well yes for the seat of the pants feeling it don't matter weather you change the the front or the back to change the ratio, Same ration will feel the same to you, HOWEVER the force on the chain and the reaction force on the swing arm changes.
Kevin Cammron goes over it well in one of his books.
I'll dig after the holidays and see if i can find it. (think its in the blue and yellow book...) theres just to many...
Maroon92 wrote:
I have a passable understanding of how the chains and sprockets work, however how does the tuning of different sizes work?
I am assuming that I could put a bigger sprocket on just the front or the back and accomplish pretty much the same thing. A smaller sprocket at either or both ends would increase acceleration right? And a larger sprocket at either or both ends would increase top speed correct?
so would one tooth bigger on both front and back be a noticeable change in top speed?
conversely, would one tooth smaller on the front and back be a noticeable change in acceleration speeds?
Adding a tooth to the front does the opposite that adding a tooth to the back does.
Larger sprocket at the front would decrease acceleration and increase top speed.
Smaller sprocket at the front would increase acceleration and decrease top speed.
Larger sprocket at the back would increase acceleration and decrease top speed.
Smaller sprocket at the back would decrease acceleration and increase top speed.
Take the front sprocket and divide it into the rear and that will give you the "gear" ratio. 35 / 10 = 3.5 The front sprocket turns 3.5 times every time the back turns once. Change the back sprocket to 40 and you get 4 to 1. For more acceleration you need a higher number. For more top speed lower.
ddavidv
SuperDork
12/27/10 5:31 a.m.
Motorcycle gearing for the math challenged:
http://gearingcommander.com/
there's a book that can be picked up at most book stores that has a chapter on anti-squat angles and stuff like that that would be VERY relevant to you right about now. if you can see the front sprocket on your bike without taking stuff apart, working out your anti-squat is a lot easier because you can actually measure from that sprocket without needing x-ray glasses
EDIT: the book I've got is Race Tech's Motorcycle Suspension Bible, and it does have a pretty good explanation of the various types of dampening setups and includes many how-tos on rebuilding various types of forks and shocks
