Sick bike parts 4stroke kit and Nexus 8 IGH gear ratio

[UtiliD]

So I'm wrapping up a build and need to figure out where to make adjustments for optimal gear ratio

26" wheels

Huasheng 49cc 4 stroke tapered shaft with
4g belt drive tranny 20t - 100t pulleys(5 to 1) to final 9t sprocket

9t sprocket to 17t SICK Bike parts left side jack shaft sprocket

Other side of Jackshaft 9t to 48t sprocket on outer side of front freewheel

Inside sprocket on front freewheel 30t sprocket to sprocket on Shimano nexus 8 hub (I've tried 18-22t)

I've only been able to use gears 4-8 and that's not going to fly.

Goal: be able to use all 8 gears and have a top speed of atleast 40-45

What do I need to change?

Will do a full build thread once it's worked out.

 

[Sidewinder Jerry]

Lord yes it's basic Math, ÷2 is the same thing as ×1/2.

If a wheel is turning a 0.527 turns per full turn of the crank it means there's an increase in reduction.

If a wheel is turning 1.615 turns per full turn of the crank it means there's a decrease in reduction.

Think of it like this:
(100÷20)×(17÷9)×(36÷9)×(18÷2)=
18.88...:1
6800÷18.88...=360

What that means at 6800 rpm where max hp is the 18t sprocket is turning 360 rpm then in 1st gear at 0.527 reduction the rear wheel will be turning 189.72 rpm.

189.72×26×⚻÷1056=14.7 mph.

In 8th gear at 6800 rpm with the 18t rear sprocket turning 360 rpm, the rear wheel will be turning 581.4 rpm.

1.615×360=581.4

581.4×26×⚻÷1056=45 mph.

Theoretically, at about 5200rpm, the OP should be able to crack 40mph.

That's with 10.:1 gearing.

(17/9) x (36/9) x (18/36) x .53 = 10.01:1, or 10:1 gear reduction in 8th gear.

That's with jimsitton calculator.

0.527 is 1st gear not 8th gear.

 

[5-7HEAVEN]

Think about what you just said.

1:1 = direct drive.

.527 = less than 1.0 = gear overdrive.

1.61 is 1st gear in a conventional car transmission.

.527 is overdrive.

 

[Sidewinder Jerry]

Shimano Alfine - Wikipedia

en.m.wikipedia.org

Click onto the Alfine 500

 

[Sidewinder Jerry]

Think about what you just said.

1:1 = direct drive.

.527 = less than 1.0 = gear overdrive.

1.61 is 1st gear in a conventional car transmission.

.527 is overdrive.

You left out the word input.

Think about this if you had a 38t chainring and a 19t rear sprocket on a pedal only bicycle the input ratio going into the hub would be 2:1; which is very common on IGH bicycles. So in 5th gear which is 1:1 for every full turn of the crank the rear wheel would turn 2 times. Therefore in 1st gear 0.527 for every full turn of the crank the rear wheel would turn 1.54 times

(38÷19)×0.527=1.54

In 8th gear for every full turn of the crank the rear wheel would turn 3.23 times.

(38÷19)×1.615=3.23

What this means is 6-8 (1.223-1.615) are your overdrive gears not 1-4 (0.527-0.851)

 

[5-7HEAVEN]

Let's talk basic math in motorized bicycles.

If we can agree that .527:1 is final drive,
then we're on the same page.

The IGH hub gears are designated in reverse, when compared to motorcycles and cars.

In a car's transmission, 2.20 or 1.61 is considered 1st gear, 1:1 is direct drive and .53 is overdrive.

A bicycle's normal gearing is designated differently, but it's semantics.

You might say an 12t rear sprocket and a 72t chainring is 6:1, according to bicycle-speak.

Try that on an mb with a 212cc engine and see what happens.....burned clutch.

Now put the 72t on the rear wheel and the bike flies.

And that's 6:1 for a motorized bike.

 

[5-7HEAVEN]

An IGH or a car's tranny might have 2 overdrives.

The machine doesn't care.

It looks at the best low gears and the best final drive it can use well.

Intermediate gears notwithstanding.

For an mb in this case, 1:1 is looked at as 3rd gear.

1.61 is low gear and .53 is high gear.

 

[Sidewinder Jerry]

Let's talk basic math in motorized bicycles.

If we can agree that .527:1 is final drive,
then we're on the same page.

The IGH hub gears are designated in reverse, when compared to motorcycles and cars.

In a car's transmission, 2.20 or 1.61 is considered 1st gear, 1:1 is direct drive and .53 is overdrive.

A bicycle's normal gearing is designated differently, but it's semantics.

You might say an 12t rear sprocket and a 72t chainring is 6:1, according to bicycle-speak.

Try that on an mb with a 212cc engine and see what happens.....burned clutch.

Now put the 72t on the rear wheel and the bike flies.

And that's 6:1 for a motorized bike.

The 0.527 is the 1st gear and lowest gear used for hill climbing and take offs

The 1.615 is the 8th gear and highest gear used for top end speeds and down hill.

Look at the site I posted Alphine 500

 

[5-7HEAVEN]

Double check your gearing with an online calculator.

 

[Sidewinder Jerry]

Double check your gearing with an online calculator.

I've been on a pedal only cycling forum for many years and am very familiar on how to do ratio calculations using an internal geared hub.

I've given you the math, explained how to do IGH calculations . Along with how to incorporate IGH calculations into reduction formulas. It's now up to you to drink the water you've been led to.

 

[5-7HEAVEN]

Forget IGH.

Think BASIC math and physics.

It's not about 4.0 accounting, pipe bending, trig and upteen years on a bicycle.

If you think .53 gearing is for climbing hills, stop posting your miscalculations.

You are doing fellow members a huge disservice.

Let's see you prove your numbers on an online calculator.

I can prove mine, but yours won't jive.