Ok so me and my buddy were arguing about how gearing affects torque. One side says that lowering your gears will give you more "torque". And the other says that the "torque" stays the same, but is just brought on earlier in the powerband.

This isnt trucks we are talking though, it's bikes. So will gearing it down yield a higher torque # on a dyno or will it just bring it on quicker in the powerband/move the powerband.

please, give me your thoughts and opinions

 

well logical i would say that the tq stays the same.... just comes on at different times..... higher rpm at same speed is going to give you more tq at that MPH vs a taller gear its going to come on at a higher speed....... i suppose the only thing that matters is if you wanna jump to 100 faster or you are after a higher top speed

 

i suggest posting it on a bike forum????

i think the law is universial tho

it'd be alot easier to do a wheelie with a bigger sprocket in the rear than bigger in the front

 

the gears arent part of the engine so they wont affect the initial output of the engine but they affect they application of tq to the ground

 

Torque is force times distance from the pivot point. If you change the size of the rear sprocket, you are effectively increasing the distance from the chain to the pivot point, so you will be applying more torque to the pivot point (the wheel, in this case). It's physics.

 

thunder- so what you are saying is that you are adding torque, but not engine torque. I agree with that.

My buddy is the one who said that the bike would put out a higher torque # on the dyno, I said it would just make it come on quicker.

So both of us are right in some way. The way he talked about it, it sounded like he was referencing engine torque.

 

To measure true engine torque you would have to measure it at the output of the engine (nto sure how MC engines work - but wherever the output of the crank is). That would completely get rid of all of the drivetrain, and would be the only true measure of engine torque. So basically there is nothing you downstream of the engine that will change the engine torque. All you are doing is changing the torque applied to the ground.

It is similar to a truck, think about why they always have you dyno in 3rd with an auto or 4th with a 6-speed, these are the 1:1 ratio gears, which will give you your closest estimation of engine torque because you only have frictional/momentum losses, not gear losses/gains. When I had my truck dynoed I did an all gear pull starting from 1st and going through 3rd, and I think I saw something in like the 900 ft-lb range in 1st gear, but a max of 410 in 3rd gear.

 

Remember that hp is torque over time, so the hp figure will be affected as well.

 

Yes, gears effect torque! Torque is a measurement of twisting or turning force. The gears of any machine are sized to manipulate the force that is needed for that application. A 2' wrench w/ a10lb. brick on it is exerting twice the torque of a 1' wrench w/a 10lb brick on it. I.E. 10 ft lb or 20ft lb of torque.