Scooterotica

I could never get my head around these numbers, so I`ll ask someone a bit sharper than me.

What is the diffence between 11-48 and 13-47

Slightly longer gearing on 13-47?

not sure understand the question

Rear sprocket is normally 46 or 47, front sprocket normally between 15 and 18

If you google Lambretta gear ratio, there is a good look up table on Beedspeed website, that give drive ratio's etc (link below)

http://beedspeed.com/html-pages/Lambret ... oChart.htm

Shows pretty much all gear and sprocket combinations

Might depend what set-up you have , but most go for final drive anywhere between 4.7 and 5.2 etc

theres also a good table on cam lam site that shows what length chain works with different sprocket setups

Sorry, thats why I`m asking.

I have a luna.

Normal original primary gears are 47-11, Sweedish gears are 48-11 with a special very short gearbox because these weren`t allowed to go faster than 30km/h.

I have now fit a standard box with a close range gear cluster but running on my 48-11 with the longest 74 link chain available.

Rimini reccomends running with a 47-13 primary with the close range cluster (I have got hold of these now) but I wonder if that translated to shorter or longer gearing overall.

13 47 is quite a bit longer if I've calculated it right.

13 47 = 3.61
11 48 = 4.36

To calculate it just divide the bigger number by the smaller number to find out how many times the smaller cog has to turn to turn the larger cog once.

Less turns to turn the bigger cog once means it's longer gearing

Same goes for the gear box. Then to get the final drive multiple the sprocket ratio by the gears ratio.

Eg

LI 150 box 4th
20 teeth cluster and 34 on the cog.
So 34/20= 1.7

Then on say 17/47 sprockets....
47/17= 2.76

Now multiplied together..
2.76x1.7= 4.692

So the final drive is 4.692 to 1 rounded up 4.7 to 1.

Simples

Cheers.

My scoot might not be able to pull that, but looking at the original vega gearing, they use 46-13 with a longer fourth gear so I think I might give it a try.

Problem is that comparing a 4 speed to a 3 speed is a little silly as I imagine a 4 speed will stand a bigger chance of keeping itself in the "power" (all 3.5 horses)

On the bright side, Lunas are super easy to change the gearing on as there is no bodywork or exhaust to take off to split the case.

The 13/47 is 17.21% longer than the 11/48 if that helps

Ok, smallest gear on mine is a 46...

Lets see if I can learn new tricks

Standard Vega gears are

46-13 on a 34 fourth = 6:90

My options are

48-11 = 4.36 19 tooth cluster and 46 3rd. will give me 2.42 x 4.36 = 10,55 ??

46-11 = 3.61 x2,42 = 8,73 ??

There is quite a big difference between the original 6.90 on a vega, but being somewhere in between what I have now and what a vega came with I should be able to pull it. (I have a vega carb,pipe and cylinder)

What do you think?

Your calcs are correct.
If you have options give them a go then decide which way you need to go.
The numbers don't mean much without knowing how those numbers work with your motor.

Tony Cassidy's gearbox visualiser should cover it.

https://avantone.wordpress.com/

corrado wrote:Tony Cassidy's gearbox visualiser should cover it.

https://avantone.wordpress.com/

Does it cover Vega etc?