Gearing ratios

Years ago when I rode enduros we would adjust gearing to accomodate terrain by changing sprockets. This was a relative inexpensive way that allowed the rider to meet those trail conditions. Has there been any thought given to economically (maybe an oxymoran) altering ratios on shaft driven scoots?

Years ago when I rode enduros we would adjust gearing to accomodate terrain by changing sprockets. This was a relative inexpensive way that allowed the rider to meet those trail conditions. Has there been any thought given to economically (maybe an oxymoran) altering ratios on shaft driven scoots?

Morning Rick

Sure lots of thoughts but with those thoughts usually comes money needed.

A number of shaft driven bikes have had rear final drive gearing exchanged with other like vehicles with different gear ratios, or even had the transmissions exchanged for transmissions with gear ratios more suited for the type of riding intended.

On the older BMW bikes there were a few different final drive ratios available with some final drives showing up on E-Bay from time to time.

It's definitely doable just not cheap.

Years ago I purchased a 2nd rear drive for my R90s as I was doing some track days and figured it would help with the tight track I was doing sessions on.

The stock 3.00:1 ratio was swapped for a 3.2:1 set.

I didn't get to do the track day that year but absolutely hated it for everyday riding. I was constantly looking for another gear as 5th now felt too low, revs too high. It didn't seem any quicker either.

Lesson: The stock ratio (IMHO) on an R90s anyway, is perfectly suited for most types of riding that I encounter.

I sold the extra drive.

RPG

For your 1100RT, the Authorities model had a lower ratio (higher numerically) final drive, the reason we were told was two-fold.

One, the Police bike was heavier with the extra battery, lighting, radio, wiring, etc,etc, and for getting up to speed from a dead stop or a freeway on ramp when initiating a traffic stop.

Depending on the department, it saved the clutch a bit also in slow going traffic.

The GS's if memory serves, had a lower final or perhaps the same ratio as the Authorities bike. It's been a long time, the brain fades.

Airheads had numerous final drive ratios depending on the engine dispacment and the model of the bike. The R90S had the tallest ratio of all, I believe .

Anton Largiader's site has the most comprehensive list:

http://www.largiader.com/

Morning Rick

The basic stock 1100 final drives were___

R/GS/RT-P___ 33:11=3.00

R 850 ____ 37:11=3.36

RT _____ 32:11=2.91

RS _____ 31:11=2.82

You can find your final drive ratio stamped on the top of your final drive next to the vent (see picture)

The 1100 (5 speed) bikes have limited options when it comes to swapping out final drives, with only 5 speeds, the overall ratio is lower in 5th gear buzzing the engine up pretty good at + legal speed limits.

About the best gear ratio set I ever had in an 1100RT was the R bike 33:11=3.00 final drive with the plus (overdrive) 5th gear set installed in the trans (expensive but effective).

If you are ever considering a used 33:11=3.00 final drive for your 1100RT then the R bike final drive is usually the best to start with as most used 33:11 drives from the RT-P are pretty beat on as most come from parted out high mile abused old police bikes. The 1100GS is also kind of a crap shoot as you never know how much water and/or sand they have digested into the final drive.

The 1150 bikes with the 6 speed gear box is a better one to play with final drive ratios (especially with the U.S. overdrive 6th gear).