41 tooth
I installed a 41 tooth rear sprocket and a new chain on my 2015 1299S. Iam very happy with the results. At the same time, I changed the rear sprocket carrier and drive cushions. If you divide 15 (teeth on the front sprocket), into 39,(teeth on the factory rear sprocket) you get 2.6. If you divide 15 into 41, (teeth on the new sprocket) you get 2.733. This is roughly a 6% difference. Consequently, you will get a 6% increase in RPM over the factory gearing. It makes the bike much more enjoyable to ride, although it has a little more tendency to wheelie, especially in the lower gears. This is well controlled by the electronics, and overall I think it is a huge improvement in riding the bike on the street and on track days. I am not a racer. I hope this helps you.
I installed a 41 tooth rear sprocket and a new chain on my 2015 1299S. Iam very happy with the results. At the same time, I changed the rear sprocket carrier and drive cushions. If you divide 15 (teeth on the front sprocket), into 39,(teeth on the factory rear sprocket) you get 2.6. If you divide 15 into 41, (teeth on the new sprocket) you get 2.733. This is roughly a 6% difference. Consequently, you will get a 6% increase in RPM over the factory gearing. It makes the bike much more enjoyable to ride, although it has a little more tendency to wheelie, especially in the lower gears. This is well controlled by the electronics, and overall I think it is a huge improvement in riding the bike on the street and on track days. I am not a racer. I hope this helps you.
