More sprocket teeth or less

I was wondering how much of a difference there could be by adding/subtracting front and rear sprocket teeth and is it worth changing if you want more power.

Changing sprocket teeth will not change power. More front teeth increases speed at the expense of torque and less increases torque at the expense of speed.

Teeth will change the gear ratio significantly. Ideally you want to use all the power on the bike. So if you are never topping it out, you can gear it a little different giving you more low end. As you add to the low end, you lose upper end. The same goes if you need to gain on the upper, you will lose lower.

Front sprockets are more of a dramatic change. 1 tooth smaller on the front = about 4 teeth more on the rear. This will give you more low end. The same goes for the opposite. 1 tooth larger in the front = about 4 teeth smaller in the rear. This will cause a lot less low end,but give you a bit more on top.

Hope this helps.

Take a look at this site. Might answer some of your questions.

 

www.gearingcommander.com

Changing sprocket teeth will not change power. More front teeth increases speed at the expense of torque and less increases torque at the expense of speed.

+1

Changing one tooth on the front is like changing 2 or 3 on the rear, and yes it can make a big difference in the way the power is delivered if you want to rev it out more you need to raise you gear ratio by going either smaller in the front or larger in the back and if you want your power more down the bottom end you need to lower your gear ratio by either raising the front or lowering the rear also a lower gear ratio will generally have a higher top speed and less acceleration and vice versa for a higher gear ratio

Two things to consider:

1- if you drop a tooth on the front your chain will rub on the swing arm pivot guide more and can eventually damage your swing arm if you do not keep a watchful eye.

2- if you go to big on the rear sprocket the chain will have issues going through some chain guide systems.

I went -1 for a few rides to check out how my bike liked it up in the hills because at $20 it was a quick and easy test. Once I decided on on a ratio that would work for me (-1 on the front = +3 on the rear) I bought a new chain and front / rear sprocket combo. Back to stock on the front to regain needed clearance and +4 on the back to give my CRF450R the necessary low end I wanted for the extreme single track I ride. I had to buy a new guide block for in front of the rear sprocket due to the increased size but all worked out.

Good luck.

All depends on how you ride. If you're doing a lot of tight trails and never get up to full speed, go ahead and add a few teeth to the rear, you'll be able to run the bike at a lower MPH without having to worry about stalling it.

 

My 2012 CRF450X has a stock gearing of 13/51, topped out at 83mph, I changed it to 14/48 for Baja racing and should be able to top out closer to 100mph. But don't gear it with plans to hold that 100mph speed. I have it geared this way so that when I'm cruising at 70-80mph I'm not so close to the rev limiter 

All depends on how you ride. If you're doing a lot of tight trails and never get up to full speed, go ahead and add a few teeth to the rear, you'll be able to run the bike at a lower MPH without having to worry about stalling it.

 

My 2012 CRF450X has a stock gearing of 13/51, topped out at 83mph, I changed it to 14/48 for Baja racing and should be able to top out closer to 100mph. But don't gear it with plans to hold that 100mph speed. I have it geared this way so that when I'm cruising at 70-80mph I'm not so close to the rev limiter 

 

Here's how the math works.  Divide 13 by 51, equals 0.2549.  Going to 14:51 gearing, divide 14 by 51 equals 0.2745.  So 0.2745-0.2549 = 0.0196 difference.  0.0196/0.2745 = 7.14% increase in speed. 

 

Going up to 14:51 will make your bike go 89 MPH if it maxes out at 83 MPH with stock gearing.  My dealer used to be a Team Green pro offroad racer in the early 90s, he raced Baja and almost won on his KX 250 before getting passed only a few miles from the finish by a CR 500.  The guy on the 500 was an inferior rider, but he knew about the long beach section where he geared his bike to run as fast as possible for over 22 miles.  He geared it 16:40, the bike would go 122 MPH!!  But the stock gearing was 14:49, which would go 87 MPH hitting the rev limiter.

Here's how the math works.  Divide 13 by 51, equals 0.2549.  Going to 14:51 gearing, divide 14 by 51 equals 0.2745.  So 0.2745-0.2549 = 0.0196 difference.  0.0196/0.2745 = 7.14% increase in speed. 

 

Going up to 14:51 will make your bike go 89 MPH if it maxes out at 83 MPH with stock gearing.  My dealer used to be a Team Green pro offroad racer in the early 90s, he raced Baja and almost won on his KX 250 before getting passed only a few miles from the finish by a CR 500.  The guy on the 500 was an inferior rider, but he knew about the long beach section where he geared his bike to run as fast as possible for over 22 miles.  He geared it 16:40, the bike would go 122 MPH!!  But the stock gearing was 14:49, which would go 87 MPH hitting the rev limiter.

14/48, not 14/51. Which means 14/48 = 0.2917. Following your formula that means 12.6% increase in speed, or 93 mph. The 83 I hit was on a dirt road so some tire slip was involved. Haven't hit top speed on pavement yet. 

 

I chose the gearing by talking to JCR Honda and they recommend 14/48 as that is the most common setup for Baja costumer bikes 

14/48, not 14/51. Which means 14/48 = 0.2917. Following your formula that means 12.6% increase in speed, or 93 mph. The 83 I hit was on a dirt road so some tire slip was involved. Haven't hit top speed on pavement yet. 

 

I chose the gearing by talking to JCR Honda and they recommend 14/48 as that is the most common setup for Baja costumer bikes 

 

I didn't realize which gearing gave you 83 MPH.  And I promise that revving out a bike max RPM for 10 seconds will make you go a whole lot faster than just revving out to max RPM for a few secs.  It's made over 15 MPH difference for me in the desert, but on pavement wouldn't be such a difference because without wheel spin, you are theoretically going as fast as the wheel is spinning. 

Thanks for all the great replies. They helped a lot. I ended up switching from 12/50 to 13/48.

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