Sunday, September 13, 2015

KLR Gear Change

In answer to the question about changing the gearing on the KLR, here is how it can be easily accomplished. A side note for the non-motorcycling readers: we change the gearing in order to maximize the bike's performance on different terrain. For example, if riding level land, you want speed. Therefore you want a low ratio number. With a 43 tooth rear sprocket and the 16 tooth front sprocket (also known as the counter sprocket) gives you a ratio is 2.69.  This is calculated by dividing the higher number by the lower:  43 divided by 16 equals 2.69.

On the other hand, if you are climbing steep mountain roads where you need lots of torque and not speed, you want a higher ratio. A 49 tooth rear sprocket coupled with a 15 tooth counter sprocket gives a ratio of 3.27.  With the higher ratio,  you give up speed in order to gain more torque. Think of a tractor, it has a lot of torque or power, but lacks speed. A red Ferrari has a lot of speed but no torque. So don't try pulling a 34 foot camping trailer with a Ferrari.

On a multi-country ride one encounters a wide variety of terrain, needing different gearing. Changing the gearing on the KLR can be easy or can be time consuming. Here is the solution I found to quickly re-gear the KLR to meet the demands of the terrain.

First remove the rear wheel from the bike.  The rear sprocket is not bolted directly to the rear wheel but to a coupling that sets inside the rear hub. Just pull the sprocket up and out to remove. Between the coupling and the actual rear hub is rubber cushioning.

Here is the rubber cushioning inside the hub. The cushioning is to absorb the push/pull jolts the drive chain places on the rear wheel giving you a smoother ride.

Here is a 49 tooth rear sprocket still mounted to the coupling. The six thick lugs sit inside the rear hub engaging the cushioning thus turning the rear wheel.

There are eight nuts holding the sprocket to the coupling. Not only is that a lot of work to remove to mount a new sprocket, but one should also use a torque wrench when tightening the nuts for the new sprocket.  Instead I carry a spare coupling with a different sprocket already properly mounted.  Then it is a simple process to change gearing by simply pulling out one coupling/sprocket and inserting the other.  Then install the wheel back on the bike.

If the rear tire wears out or has a flat, remove it and install the spare tire. To keep the same gear ratio, pull the coupling/sprocket from the flat tire and insert in the spare tire.  

To answer a question about the frisbee on the spare tire:  the spare tire is mounted on the tool box with the brake rotor facing up. If the rotor was facing down, the constant bouncing and banging around would bend or deform the rotor, making it useless for braking later.  A spare coupling with mounted sprocket is carried inside the toolbox, not here on the spare mount. The white ring under the wheel is a small frisbee to keep the aluminum wheel from being damaged by the steel mount.

With the rotor facing up, in order to protect it from weather and damage, a larger white frisbee is placed on top. Both frisbees are inexpensive Walmart items.

The large washer, a castle nut and clip hold everything in place. To make sure the spare does not disappear at night, a steel cable is thread through the spokes of the wheel, a gas can and locked to the toolbox. 

Little by little Da'mit is coming together for the big ride. This weekend the anemic factory horn was replaced with a Bad Boy air horn that will wake up any texting or dozing taxi driver...  instantly.

Getting ready for a side trip soon, will post photos asap.

Ride safe