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Discussion Starter #1
Right my bike has 16/45 gearing that the previous owner put on. Thinking about switching the gearing to 15/42. Would it be much of a difference? Or would it be pretty similar to what's on the bike now?

TIA
 

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45 / 16 = 2.8125

42 / 15 = 2.8

So theoretically your front sprocket will turn by 0.0125 turns less for each rear sprocket's full rotation. That means it'll be a bit "longer" geared than with the 16/45.
Probably a couple of mph more on the same rpms

I don't think that you'll notice much on the throttle while riding it though
 

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You'd achieve a tad more power at the rear wheel, since a 15T sprocket is easier for your motor to turn than a 16T, but I'm not sure you'd notice it. I'm not smart enough to convert it to torque figures.
Only variable IS torque.
Power will stay the same.
Can't work out power without a torque figure to start with.
Power = torque X rpm

Smaller drive sprocket = more torque + less rpm = same power
 

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Only variable IS torque.
Power will stay the same.
Can't work out power without a torque figure to start with.
Power = torque X rpm

Smaller drive sprocket = more torque + less rpm = same power
Right. I should've said 'torque' ... and as the old saying goes, "Horsepower sells cars; torque wins races."

Do you think 16/45 (2.8125) gearing and 15/42 (2.8) gearing would accelerate at essentially the same rate? (i.e. no benefit from the fact that the front sprocket is 15T vs 16T?)
 

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Discussion Starter #10
Do you think 16/45 (2.8125) gearing and 15/42 (2.8) gearing would accelerate at essentially the same rate? (i.e. no benefit from the fact that the front sprocket is 15T vs 16T?)
This is pretty much the same thing I was wondering, and why I asked the question.
 

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You'll get 0.446429% difference in torque at the back wheel.
So the same difference in acceleration.
Is it worth it?
Try it & let me know.
I do know that bigger sprockets won't wear as quickly. A 16T front should last 6.6% longer than a 15T.
The steel guide in the sprocket cover is also designed to help stop the chain flying off a 16T sprocket not a 15T.
Ever seen the damage a broken chain can do to engine casings?
Exactly why I changed back to a 16T drive sprocket & my bikes better for it.
Piss about with the gearing at your peril.
 

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You'll get 0.446429% difference in torque at the back wheel.
So the same difference in acceleration.
Is it worth it?
Try it & let me know.
I do know that bigger sprockets won't wear as quickly. A 16T front should last 6.6% longer than a 15T.
The steel guide in the sprocket cover is also designed to help stop the chain flying off a 16T sprocket not a 15T.
Ever seen the damage a broken chain can do to engine casings?
Exactly why I changed back to a 16T drive sprocket & my bikes better for it.
Piss about with the gearing at your peril.
i generally keep the counter sprocket stock as well and just add teeth to the back. now it might not make much difference on a 15t, but as far as i know going lower teeth on the CS makes the chains turning radius tighter which can wear the chain faster.

i went with a 520 steel/aluminum 16/43 set-up. coming from stock gearing to this and adding the 1/6 turn throttle i'm a little nervous lol :p
 

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My concern about going with more torque is rear tire wear, that is why I have opted (so far) with sticking to stock gearing.
 

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The engine's power and torque output cannot be changed by gear combinations.
it originates at the crank and you can only change it by working on the engine itself.

Changing the final gearing ration however, "moves" the power and torque numbers across the rpm range.
If you have a certain torque number at 7000rpm with the stock gearing and use a +2T sprocket at the rear then you shift that torque number to a few rpms lower. Same goes for the power output.

The final outcome on swapping gearing combinations is something to be calculated as a whole due to the chain linkage of the two sprockets.

Changing the front sprocket to a 15T doesn't mean anything without knowing how many teeth the rear one has at that moment. The same goes for the rear wheel's circumference which is a factor to this whole equation. Keeping the same gearing for example and changing the rear tire to a 190/55 or the rear wheel to a 16" would present the same effect on the bike as if you have changed the final drive's gear(s).

Comparing with the stock 40/16 gearing which gives a ratio of 2.5, answering a question like: "Should I roll on faster if I swap the front with a 15T sprocket?"
....isn't that straight forward.

Of course if you keep the rear at 40T and use a 15 at the front, the ratio changes to 2.66666 which means that "yes you should see the same torque and HP at lower rpms than before."

But if the rear is changed to a 37T then the ratio changes to 2.46666 which means that "No, the same amount of torque and HP will come to the rear wheel at higher rpms than before"

It's all about how much torque must the engine use, from it's arsenal, to beat the bike mass's inertia.
Bigger final drive's ratio number means less torque used so the rpm climbs faster but the torque dries up sooner.
Smaller final drive's ratio number means more torque used to get the bike moving so the rpms climbs slower but the torque finally comes almost all of it on the rear wheel in higher rpms.

The whole point is that the HP and torque, the engine can produce, are touching the road once the bike's + rider's masses are moving and all the earth's dynamic forces on them are equalized by the energy they have absorbed, by the engine, to get them mobile.
Then you get the engine's actual power on the rear wheel.
Simple physics I think.......

Hope I helped!
 

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Makis, do you use voice recognition software ?

Man I wish I could type as well as you do,so often I want to chime-in and just do-not have the speed at the keyboard to do so.

That said very well written post sir.


And remember for those of you running the stock set-up if your willing to spend $25 bucks get a 15T 530 afam front it's close to adding 3 teeth in the rear.;)
 

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Makis, do you use voice recognition software ?

Man I wish I could type as well as you do,so often I want to chime-in and just do-not have the speed at the keyboard to do so.

That said very well written post sir.


And remember for those of you running the stock set-up if your willing to spend $25 bucks get a 15T 530 afam front it's close to adding 3 teeth in the rear.;)
No voice recognition on this end of the line.

Have been doing a lot of typing, since I'm a forum moderator, so I have the speed but lack the vocabulary since English is not my native tongue.
I guess we all need each other to make this place work after all :)

Thank you for your kind words.....took me while to come up with the right words actually so that my exact thoughts could be typed on the screen :rolleyes:
 

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That was fucking amazing Maki! :)
You really broke it down brother. Good work, awesome description, clearly you have a good understanding of how stuff works. ;)

I remember when you were trying several different sprocket combinations, which one did you end up liking the best for your bike?
 

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No voice recognition on this end of the line.

Have been doing a lot of typing, since I'm a forum moderator, so I have the speed but lack the vocabulary since English is not my native tongue.
I guess we all need each other to make this place work after all :)

Thank you for your kind words.....took me while to come up with the right words actually so that my exact thoughts could be typed on the screen :rolleyes:
Makis, I can tell only every so often that English isn't your first language ... which is impressive.

Of course, what else would I say now that I know you're a mod?! :p:D;)
 

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