18 spd vs 15spd/9LL

Ditto, exactly what I was told more than 40 years ago.

 

RTX14609B

 

I'm gonna look into the power flo charts and see if I can find the missing gears in the 13 and 18 speed transmission.

 

18 Speed
Here is the low gear of the 18 speed transmission power flow chart.
Its identical to the 10 speed.



10 Speed 1st Gear
Here is 1st gear in a 10 speed OD Transmission
It has the same power flow as the 18 and 13 speed.

10 Speed 6th Gear
Here is 6th gear in a 10 speed overdrive transmission.
This no doubt is the same gears that are left out in the 18 and 13 speed transmissions. They are there but not recommended to use.
The 10 speed is missing the 2nd row of gears counting back to front, that the 13 and 18 have.

I looked through all 18 power flow charts and don't see this config so it must be the omitted gears in the 13 and 18.