Sprocket Size Speed vs. Torque--Rookie Question...

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mjp8081   100 W

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Sprocket Size Speed vs. Torque--Rookie Question...

Post by mjp8081 » Apr 24 2015 8:54pm

After years of owning and working on my Enduro motorbikes, I need someone to remind me of the old rule about the 2 sprocket sizes, drive vs. driven/motor vs. wheel and how they effect speed and torque. Is it

Larger motor sprocket=more torque, less speed
Larger wheel sprocket=less speed, more torque


**corrected:**
Larger (# of T) motor sprocket=More speed, less torque
Larger (# of T) wheel sprocket=More torque, less speed

Is that how it goes? I seem to remember it being an inverse relationship.

Rookie question, thanks.

I ordered 2x 10T motor sprockets, now I'm trying to calculate the wheel sprocket size. (Either 54, 58, or 60T)
Using 2x Tacon Bigfoot 160s
Last edited by mjp8081 on Apr 28 2015 7:21pm, edited 3 times in total.
RV house batteries 2x 150ah LiFePO4 Deep Cycle, Shenzhen LithPower Green
Current homebuilt eMTB: MBS Comp 95, 8S, 2x Turnigy Trackstar 200a, 2x Tacon Bigfoot 160s--RWD. 1:6 ratio, custom aluminum MBS truck mount
Former board: Custom MBS Comp 95 36v 20aH LiFePo4 800w single chain drive motor with wired trigger throttle. Powered parts from e-Glide

CSN   100 W

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Re: Sprocket Size Speed vs. Torque--Rookie Question...

Post by CSN » Apr 24 2015 9:37pm

and your wheel size is???

mjp8081   100 W

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Re: Sprocket Size Speed vs. Torque--Rookie Question...

Post by mjp8081 » Apr 24 2015 11:03pm

CSN wrote:and your wheel size is???
8" MBS...but I'm asking in general terms about the relationship between the drive sprocket and the wheel (driven) sprocket, as a mechanical rule, as it applies to anything with chain drive--bikes, motorcycles, etc. I believe there is an inverse relationship between the two--I just can't remember which is which.

Actually, nevermind...sorry, I finally found a chart that explains.

http://cdn1.bikebandit-images.com/marke ... -chart.jpg
RV house batteries 2x 150ah LiFePO4 Deep Cycle, Shenzhen LithPower Green
Current homebuilt eMTB: MBS Comp 95, 8S, 2x Turnigy Trackstar 200a, 2x Tacon Bigfoot 160s--RWD. 1:6 ratio, custom aluminum MBS truck mount
Former board: Custom MBS Comp 95 36v 20aH LiFePo4 800w single chain drive motor with wired trigger throttle. Powered parts from e-Glide

chuttney1   100 W

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Re: Sprocket Size Speed vs. Torque--Rookie Question...

Post by chuttney1 » Apr 25 2015 2:39am

From the question you asked, it would be a yes to both what you are asking. I probably believe you already get the concept of the final drive ratio....

brent   1 W

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Re: Sprocket Size Speed vs. Torque--Rookie Question...

Post by brent » Apr 25 2015 4:20am

I think it'd actually be no, for both. For the same wheel pulley, more teeth on the motor pulley would make your board faster, not slower.

mjp8081   100 W

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Posts: 164
Joined: May 12 2009 3:25am
Location: San Francisco Bay Area

Re: Sprocket Size Speed vs. Torque--Rookie Question...

Post by mjp8081 » Apr 28 2015 7:17pm

Yes...corrected:

Larger (# of T) motor sprocket=More speed, less torque
Larger (# of T) wheel sprocket=More torque, less speed

I corrected the OP to avoid confusion
RV house batteries 2x 150ah LiFePO4 Deep Cycle, Shenzhen LithPower Green
Current homebuilt eMTB: MBS Comp 95, 8S, 2x Turnigy Trackstar 200a, 2x Tacon Bigfoot 160s--RWD. 1:6 ratio, custom aluminum MBS truck mount
Former board: Custom MBS Comp 95 36v 20aH LiFePo4 800w single chain drive motor with wired trigger throttle. Powered parts from e-Glide

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