11-09-2015, 01:38 AM
Ferret, you are one of those that as I discovered the forum in early 2015, I appreciate and learn from your posts, but only joined now because I had questions.
Thanks for your reply. I never doubted 3250 was the rpm from members posts, but from the Transmission gear ratio data that many have posted, I don't understand how it is possible. If the 2013 does 4000 rpm in 5th (Tx ratio is 1.034 - 30/29) with a front/rear 18/39 sprocket combination and the 2014 has a 0.964 ratio in 6th with a 18/40 sprocket combination, then the 2014 should theoretically only be able to do 3824 rpm in 6th - (0.964/1.034) * (40/39) * 4000. For the math to work out correct allowing an rpm of 3250rpm in 6th on a 2014, the sixth gear ratio must be 0.8191 not 0.964.
For the following equations it is, Engine RPM / Transmission ratio equals the front sprocket rpm. Then Multiply (*) by the sprocket ratios = rear wheel rpm.
On a 2013, 4000 / 1.034 = 3868 then * 18/39 = 1785 wheel rpm. In order to keep same 70mph speed (wheel rpm) on a 2014 in 6th, a Tx ratio of 0.8191 must be used: 3250 / 0.8191 = 3967 then * 18/40 = 1785 wheel rpm
If 0.8191 is the "real" ratio everything makes sense, but if it is actually 0.964 than something else is in the picture I am unaware of. This is my dilemma and reason for this thread/post.
In a nutshell, you confirmed my reasoning to do a 35 vs a 37 rear tooth sprocket. That will enable a 3400 rpm in 5th at 70mph. Talking with pekingduck, there should be no problem starting in 1st with only a 15% reduction in ratio. After that everything is in sync.
Thanks for your reply. I never doubted 3250 was the rpm from members posts, but from the Transmission gear ratio data that many have posted, I don't understand how it is possible. If the 2013 does 4000 rpm in 5th (Tx ratio is 1.034 - 30/29) with a front/rear 18/39 sprocket combination and the 2014 has a 0.964 ratio in 6th with a 18/40 sprocket combination, then the 2014 should theoretically only be able to do 3824 rpm in 6th - (0.964/1.034) * (40/39) * 4000. For the math to work out correct allowing an rpm of 3250rpm in 6th on a 2014, the sixth gear ratio must be 0.8191 not 0.964.
For the following equations it is, Engine RPM / Transmission ratio equals the front sprocket rpm. Then Multiply (*) by the sprocket ratios = rear wheel rpm.
On a 2013, 4000 / 1.034 = 3868 then * 18/39 = 1785 wheel rpm. In order to keep same 70mph speed (wheel rpm) on a 2014 in 6th, a Tx ratio of 0.8191 must be used: 3250 / 0.8191 = 3967 then * 18/40 = 1785 wheel rpm
If 0.8191 is the "real" ratio everything makes sense, but if it is actually 0.964 than something else is in the picture I am unaware of. This is my dilemma and reason for this thread/post.
In a nutshell, you confirmed my reasoning to do a 35 vs a 37 rear tooth sprocket. That will enable a 3400 rpm in 5th at 70mph. Talking with pekingduck, there should be no problem starting in 1st with only a 15% reduction in ratio. After that everything is in sync.