11 tooth engine gear

HumanPerson

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I see this 11 tooth engine sprocket from ZEDA, what exactly will this do for my setup?
 
might make your top speed faster and your hill climbing less powerful - this is only if it doesn't cause your chain to bind inside drive cover
 
Well i'm not looking for anoy more speed on the top end, I would like some more hill pumpin power though :D
Yeah, I thought there would be some dremel work on the cover. Was just wondering if anyone else uses them and what they really have to do, even if it is worth it.
Thanks crassius :)
 
If we say that the resistance to movement at the wheel is infinite, like you're on the impossible hill just putting torque into the drivetrain, the increase of drive sprocket radius is a decrease in the load being put on the chain, thus allowing you to use a more beastly higher torque engine or a lighter chain.

This is not the same as a smaller rear sprocket. Compact gearing puts more load on the chain and sprocket teeth.

What you do with the ratio is another matter. Sure, 11:44 is the same ratio as 10:40 but it is not the same.
 
Well i'm not looking for anoy more speed on the top end, I would like some more hill pumpin power though :D
Yeah, I thought there would be some dremel work on the cover. Was just wondering if anyone else uses them and what they really have to do, even if it is worth it.
Thanks crassius :)
I use the 11t sprocket on the clutch shaft and it fits even with the 415 chain,like Furry said it reduces load on the chain going around it so you can have more torque safely but incresses over all load and at the rear gear!I run 11/34 on the street witch gives me a final ratio of 3.09 chain and tooth wear on the gear is minimal compared to running my 26t gear out back that gives a final ratio of 2.39 that one is harder to turn all around and streched the chain after the first hours ride!
 
I'm pretty confused now :D
So with the 40tooth rear wheel sprocket and an 11 tooth engine sprocket, will that help climbing hills or on the lower RPM area, will that be any better for performance in that range (low rpm range)?
Right now the 10 and 40 seems pretty good, I just thought 11/40 would be better and less stressful on the engine and drive components.
Please clue me in here :D

Thanks guys! :)
 
Let's do some math, it will be worth it, I promise.

Lets assume that your engine has a 10t gear on the engine crankshaft, 41t gear on the clutch, a engine output sprocket with 10t, and you have a 40t rear sprocket.
THEN:
Gear Ratio = (41/10) * (40/10) = 16.40:1

Soo, with the 10t sprocket, we have a gear ratio of 16.4. Cool stuff. Let's keep making assumptions..

Now, let's assume your engine spins 6000 RPM. At that 6000 RPM with a 26" wheel, your speed will be:
Speed = (RPM) / (Gear Ratio * (Some Factor which is a function of wheel diameter))

I don't feel like doing the math, so I used a calculator, the speed ends up being 28.3 mph. Feel free to do the unit conversion if youd like; I didnt like.

Sooo we have:

Speed = (RPM) / (Gear Ratio * (Some Factor which is a function of wheel diameter))
Speed = (6000) / (16.40 * (Some Factor which is a function of wheel diameter)) = 28.3 mph

Lets solve for the factor so it can be used later:
==> ( Some Factor which is a function of wheel diameter) =12.93. This has some weird units along with it, Ill leave those of because Id like to. Id also like to just ignore any error which might show up as a result of rounding that down, so I will.
Anyways, now we finally come to the whole point of this mental exercise:

So you want to know what happens when you change the engine output sprocket to 11t?
Lets just plug it into our handy formula we derived..

Speed = (RPM) / (Gear Ratio * (Some Factor which is a function of wheel diameter))
Speed = (6000) / (( (41/10) * (40/11) ) * (12.93))= 31.1 mph.


So, if your setup happens to be the exact same as the one described by the above assumtpions, then by switch to the 11t gear you will increase your speed at 6000 rpm by about 3 mph.


Can we learn anything from this to prevent doing math ever again?!I would sure hope so. Play with the formula, note that:
1) The change in speed is about equal to current speed * a ratio of rear gears changed.
or, New speed = Current Speed * (Old rear cog teeth count / New rear gear cog count)

2) The change in speed is about equal to current speed * a ratio of front gears changed
or, New speed = Current speed * (New front cog teeth count / Old front cog teeth count)
 
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while doing the math, think about how increasing sprocket radius on front is same effect as decreasing sprocket radius on rear
 
while doing the math, think about how increasing sprocket radius on front is same effect as decreasing sprocket radius on rear

I propose the creation of a new dimensionless number to take into account the above:

Let's call it the ronALD number, because I can.

ronALD = ( (Old rear cog teeth count / New rear gear cog count) / (Old front cog teeth count / New front cog teeth count) )

With the ronALD number, math is a thing of the past!

We can now know our new speed resulting from gear changes, both front and rear, with just one product! Now it doesn't matter what size gear is on your rear or front; all that matters is ronALD.

New Speed = Old Speed * ronALD
 
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