Gear range or Cassette size for shifter kit

[HseLoMein]

Hey Guys,

So I got the shifter kit with a stock 66cc engine installed on my bike and been riding it around. It is great and definately a huge improvement in virbration reduction. I havent had a chance to test it up a hill yet, i will do that tomorrow. I have the shifter kit on a what was a 10 speed bike.

Before the shifter kit I was going between 28-31 mph tops and after the kit has been installed i am still going the same speed maybe one mile less.

Is there a cassette size that will help me acheive a speed greater than 30 mph? i really want to go no faster than 35 mph. Do you think going to a 6 or 7 speed cassette will help?

 

[NunyaBidness]

It's not the number of gears on a cassette that will help you go faster, rather it is the number of teeth on the gears that help with speed. The fewer teeth on the cogs on the cassette the better for speed.

Other than that I'd wait on Pablo or Ghost0 to chime in with their recommendations.

 

[wildemere]

Cassettes are used on newer high end bikes with the freewheel integrated to the hub. The sprocket "cassette" slide on to a spline. This system allows for a tiny top gear, 11t or 12t is possible.

What you probably have is a "cluster" or freewheel if its an old bike. It screws on the hub and the freewheel is built into the cluster not the wheel. 14t is usually the smallest gear possible. I have seen smaller but it is rare and used on old school racing bikes.

A 14 to 28 is the most common setup here. 14 to 32t or bigger will require a special rear derailleur. If you really have a cassette rear hub the you can have 12 to 30 or something like that.

 

[HseLoMein]

Wildemere,

According to your description its a 5 speed freewheel. Have you heard of anything other than 14 to 28 teeth. Im wondering if i change I can get it to less than 14 teeth.

 

[wildemere]

You will have to get a new rear hub to get 12 or 13t.

Read this to help you decide.

Shimano Cassettes & Freehubs, by Sheldon Brown

But remember if you strip or damage a cassete hub its expensive, but with a freewheel you just replace the cluster.

You might find a 13t freewheel hub if you search hard.

 

[Ghost0]

Here is how to calculate gearing on the Shift Kit and how it relates to standard gearing.

 

[Ghost0]

Let me add this to that, like I said I have a 13-34, 6 speed cassette, my 4th gear is almost exactly the same as running a 44t sprocket. In 4th gear I top out at about 34 mph and the engine is spinning pretty good. I can get 38 to 40 in 5th. When I shift in to 6th it now tops out at 35mph. So my point is that the engine only produces so much power and no matter how you gear it you won't go any faster. The only way to go faster is to increase horse power or decrease drag.

Let me ask this, have you seen how fast it goes in 4th gear? How fast in 5th gear? If your 4th gear actually gets you going faster than 5th then increasing your gearing won't get you anywhere. If 5th goes faster than 4th you might want to try a different cassette, which was already mentioned or try an 11 tooth jackshaft sprocket. That will increase you entire gearing. So your low gears won't be as low but your top gear will be taller.

 

[wildemere]

This spreadsheet is good.

I found it a while back and customized it a little, not all my work.

Has tabs for Shifter Kit, Stock, Average speeds, Consumption and tyre sizes.

 

[old motorbike]

I used one of my old front sprockets from the original that has more teeth than the one that came with the shift kit. Now I can get about 20 easy from first gear. 30 is loafing along in 5th gear. Less rpm, less vibration.