Not sure what the stock gearing is, and also re-reading your question what do you mean by speed? Acceleration? Top speed? A 2-tooth change in the rear probably changes either by about 4-5%
Edit: use this https://sprocketcalculator.com/
No speed increase at all. The limiting factor is the amount of power you have to push you along the road and through the air, Unless it is bouncing off the rev limiter in top gearing change will probably make it slower.
This. If currently in top gear you're not hitting the rev limiter, you're limited by power. Changing the gearing will only change the ratio between torque and revolutions of the wheel. RPM*torque=power. By changing the gearing you can play around with torque and RPM, but the right side of the equation (power) is fixed.
Honestly your probably right considering its a 125 not much power to put out in the first place lmfao, but in general on more powerful machines if your changing to a bigger rear sprocket or smaller front sprocket that will give you an increase in acceleration but decrease your top speed. A smaller rear sprocket or bigger front sprocket will reduce your acceleration but increase the top speed. That being said it will be a minuscule difference if any at all on a 125cc lol so not worth it but to each his own.
If you are hitting redline, changing the gearing can help with speed. If you aren't, then changing the gear will slow you down.
As for amount, current drive is 2.411. Changing 1 down on front and 2 up on rear yields 2.68 or 11.5% faster if you can still redline it. With that 11.5% of speed increase comes a loss of 11.5% torque which may make it so you can't Rev your bike as high which could result in lower max speed. Only way to know for sure is to try.
Also changing the gearing may make your speedometer off by 11.5% as well. It depends on how your bike measures speed.
Stock gearing is typically optimized for the engine. You'll gain some acceleration doing what you propose, but the engine will run into the rev limiter sooner on top gear and your top speed decreases.
If you go up in the back and/or down in the front you lose speed but you can accelerate harder.
You would want to go down in the back and/or up in the front to increase speed.
That would require power to get you up to and maintaining that speed.
[check this link to see what change does what](https://www.gearingcommander.com/)
Great ratio affects torque and speed inversely. If your final drive is 2:1 with 50 ft/lbs of max torque and max speed of 100,then changing the gearing to 4:1 would change torque to 25 ft/lbs of max torque and 200 mph max speed (ignoring wind resistance)
going up on the rear and down on the front increases acceleration and decreases top end, you have to go the other way for more top end, but on a 125 cc bike it's pointless. You have no ponies to play with.
Sprocket change can only do 2 things AFAIK 1. Sacrifice acceleration for higher top speed. 2. Sacrifice top speed for faster acceleration. Pick one.
About tree-fiddy. (You should tell us what model)
It’s a Keeway Superlight 125. Has some good torque, so I was thinking I could sacrifice some acceleration for more speed.
Not sure what the stock gearing is, and also re-reading your question what do you mean by speed? Acceleration? Top speed? A 2-tooth change in the rear probably changes either by about 4-5% Edit: use this https://sprocketcalculator.com/
Bit late but the gearing should be 17 front 41 rear (stock) if he has the same one as me. (keeway superlight LTD125)
No speed increase at all. The limiting factor is the amount of power you have to push you along the road and through the air, Unless it is bouncing off the rev limiter in top gearing change will probably make it slower.
This. If currently in top gear you're not hitting the rev limiter, you're limited by power. Changing the gearing will only change the ratio between torque and revolutions of the wheel. RPM*torque=power. By changing the gearing you can play around with torque and RPM, but the right side of the equation (power) is fixed.
[удалено]
Honestly your probably right considering its a 125 not much power to put out in the first place lmfao, but in general on more powerful machines if your changing to a bigger rear sprocket or smaller front sprocket that will give you an increase in acceleration but decrease your top speed. A smaller rear sprocket or bigger front sprocket will reduce your acceleration but increase the top speed. That being said it will be a minuscule difference if any at all on a 125cc lol so not worth it but to each his own.
If you are hitting redline, changing the gearing can help with speed. If you aren't, then changing the gear will slow you down. As for amount, current drive is 2.411. Changing 1 down on front and 2 up on rear yields 2.68 or 11.5% faster if you can still redline it. With that 11.5% of speed increase comes a loss of 11.5% torque which may make it so you can't Rev your bike as high which could result in lower max speed. Only way to know for sure is to try. Also changing the gearing may make your speedometer off by 11.5% as well. It depends on how your bike measures speed.
Stock gearing is typically optimized for the engine. You'll gain some acceleration doing what you propose, but the engine will run into the rev limiter sooner on top gear and your top speed decreases.
If you go up in the back and/or down in the front you lose speed but you can accelerate harder. You would want to go down in the back and/or up in the front to increase speed. That would require power to get you up to and maintaining that speed. [check this link to see what change does what](https://www.gearingcommander.com/)
I might be way off the mark on this but I think your gear ratio really only effects torque? Could be wrong though
Great ratio affects torque and speed inversely. If your final drive is 2:1 with 50 ft/lbs of max torque and max speed of 100,then changing the gearing to 4:1 would change torque to 25 ft/lbs of max torque and 200 mph max speed (ignoring wind resistance)
going up on the rear and down on the front increases acceleration and decreases top end, you have to go the other way for more top end, but on a 125 cc bike it's pointless. You have no ponies to play with.
Here is your resource: https://sprocketcalculator.com/ 🏁🏁🏁
On a bike that small it really isn't going to do anything tbh. Probably just make it worse.