any rule of thumb for sprockets??

with my kitted V1 I have a 75cc kit on it and does 40 rear sprocket is a 42 and front is a 11 if i put my 32 tooth on there how many more mph top end would I be lookin out I know it will kill my low end but its flat around these parts.

is there any rule of thumb for sprcokets lke you gain 1mph for every tooth you go down or something along thoes line?


Re: any rule of thumb for sprockets??

Nothing that simple.

Top speed is going to be the product of your peak RPMs through any gearing.

gearing taller (as in less rear teeth) will make it so that your bike is moving faster for any given RPM, ie at 10,000 rpm your bike will be moving faster with taller gearing than with lower gearing. However, when gearing taller you can expect that you will be losing some pulling power, therefore your bike will probably not rev out as high, so there are two forces fighting eachother there. Gear too tall, and your bike will not only lose torque, but it won't have the pull to bring you up to high RPMS and you could actually have less top speed than a lower gearing. This is where your kit is helpful, because while you only gained a few MPH's when you introduced that big ol' kit, the extra torque will allow you to gear up significantly, while still revving out high and have some to spare off the line. Ideal gearing=acceptable torque+acceptable top speed, so keep these things in mind and play with it a bit. So, no, there is no rule of thumb, but I hope that any this is helpful in finding the your ideal gearing for your bike! trial and error! I tend to just gear out a little until I am still happy with torque, and then just end out with the top speed I am granted.

Re: any rule of thumb for sprockets??

tracy you explained that perfectly.

Re: any rule of thumb for sprockets??

Thanks Aces, I feel it really helps to have those things in mind.

--I came back to add that you have to be especially careful here with pipes with high powerbands. If you have a pipe that currently hits at 30+, gearing much taller could make your bike hit that same RPM at 35 or even 40 with really tall gearing (assuming you can still get there without your pipe's help). So be weary also if you you like the speed where your pipe hits, because it will likely change with the gearing.

any rule of thumb for sprockets??

wow thanks for the great info would the same be true for the front? i know bigger front mean more top end smaller mesn more torque

Re: any rule of thumb for sprockets??

Bigger teeth on the front = smaller teeth on the back. It's the ratio that counts.

just keep in mind, changing from an 11 to a 15 front is bigger than a 42 to 37 rear.

42/11= 3.89 (now)

37/11= 3.36 (four teeth less in the back)

42/15= 2.8 (four teeth more in the front= much bigger change)

that is just to demonstrate, that when you are dealing with ratios, changing the smaller gear will have a bigger impact than the larger gear.(per tooth change) So, unless you are looking for drastic changes, don't go crazy on the front.

Re: any rule of thumb for sprockets??

Or us a 12 tooth front and split the difference:

42/12 = 3.50

any rule of thumb for sprockets??

#CrazyWayne™ rocks. #CrazyWayne /

Josh a V1 with 70+cc with 11 – 32 is 2.909 to one or 134.59339 RPM,s Per MPH don't to hard on the clutch.

For flat land riding i would run 3.1 to 1 = 143 RPM,s Per MPH.

For city and or hills up to 20% = in 100 ft you clime 20 ft run 3.4 to 1 = 157 RPM,s Per MPH.

20% + grade 3.5 to 1 = 162 RPM,s Per MPH

Josh Get a 40 or 42 rear sprocket.

10-40=4 to one 11-40=3.64 to 1 12-40=3.333 to one 13-40=3.07 to one .

10-42=4.2 to one 11-42=3.8 to one 12-42=3.5 to one 13-42=3.23 to one.

I think for flat city riding 13-42=3.23 to one= 149.47 RPM,s Per MPH will BLAST the best 7474 RPM,s at 50 MPH all day.

Let me now how it works out for you.

Fast Bat out

any rule of thumb for sprockets??

I am running a 70cc V1 kit and have a 10/34 set up. The bike still has a bunch of low end will do 45+. I am going to a 36 rear to try to get the RPM's up a little so I can get a little more top end and also get some of my low end back. I am going to do a bunch of gear tunning this season. I have 32,34,36,40,42 and 45 rear sprockets and have 10,11 and 12 front sprockets to play with.

any rule of thumb for sprockets??

wow thatnks powerchair lots of usful info i think im gonna try changing my 11 tooth out for a 9 and leave in the 32 rear my low end is pretty bad with the 11:32gearing but I was able to top out at 53 and was able to hold at 51

any rule of thumb for sprockets??

#CrazyWayne™ rocks. #CrazyWayne /


Having a 9 /32 puts more stress / wear on trans out put shaft rear axle wheel bearings sprockets and chain.

I run 12 / 42 = 3.5 to 1 = 162 rpm's per mph 7287rpm's @45mph.

Fast Bat out

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