Chrome/Molybdenum Sprockets Frequently asked questions:

How can a steel sprocket be as light as aluminum? By using less of it! The steel that is used on our sprockets is approximately 5 times stronger that aluminum. In theory, you would only need one fifth the amount of material. In practice we used one third. The result is a sprocket that is stronger and far more wear resistant.

How strong is an Ironman sprocket? Each model of sprocket is tested on a fixture that produces 5500 pounds of chain tension over the sprocket. In actuality, the maximum chain tension that an open class motorcycle can transmit is in the range of 1800 pounds.

Why does an Ironman sprocket last so long? They are extremely wear resistant because they are made of hardened alloy steel, similar to a chain's roller. Aluminum is a very poor material when exposed to abrasive materials such as mud and sand.

Why don't we use "mud cleaning" slots? Mud cleaning slots accelerate tooth wear and their benefit is questionable. These cleaning features on some competitor's sprockets reduce the contact area between the chain roller and sprocket tooth, resulting in much faster wear. We have found that these features offer little or no performance advantages in muddy conditions. 

What is the purpose of the nonsymmetrical spokes? The patented design on the Dirt Tricks Chromoly sprocket was developed using Finite Element (FE) stress analysis software. As the chain is put into tension under power, the resulting forces to the rear sprocket are attempting to collapse as well as shear the rim from the hub. The unique spoke design provides equally spaced support around the rim to prevent collapse. The angle of the spokes, transfers the load diagonally to the hub, doing so with only compressive stresses to the spokes.

Since the sprockets are so strong, does the chain wear out faster?  Nope, just the opposite! Wear goes hand in hand. If the chain has good valleys to roll into, it will ultimately last much longer on average than with cheap-o sprockets. As a sprocket wears, the valley grows as the roller drives into and deforms the tooth. The sloppy fit of the roller into an enlarged valley will accelerate chain wear or "stretch".  That is why the rule is "always replace your chain and sprockets as a set." Our sprockets are the exception to the rule as it may be possible to go through several chains before the sprockets are at the wear limit. The chain will still wear out as tiny particles of dirt eat away the the pins causing very small amounts of slack (wear) on each pin, but overall any chain you use will have a greater life with our sprockets. We always recommend O-ring chains as they will outlast a non-O ring chain by 5 to 10 times. O-rings help protect the pins, thus their lifespan is far greater than the unprotected non-O ring chains.  

Why is my front sprocket discolored?   Its from heat treating and it's normal. We heat treat our sprockets very carefully  within a strict hardness range. They are then Rockwell tested for accuracy.  During this process many different things can happen depending on a wide variety of factors. Sprockets may be bright gold, dull gold or even have a blue or purple tint. 

KTM Front Sprockets and Oil Leakage:  There seams to be a number of myths floating that associate certain front sprockets with oil leakage on KTM four-strokes. The sectioned model below should clarify this. Oil is sealed at two points on the countershaft: Everything to the right of the lip seal (cream color) is submersed in oil.

First at the O-ring. This is a static or non-sliding seal that rotates with the countershaft/sprocket. As can be seen, the dome washer on the outside of the sprocket loads all of the elements, beginning with the screw, then the dome washer, the seal spacer bushing, an O-ring, and finally the inner race of the countershaft bearing. If the dome washer becomes distorted and flattened, it allow this stack of parts to develop clearance between them including the O-ring seal faces. If you are leaking oil around your sprocket, first check to see if the dome washer can be spun with some channel locks. If it can be spun, buy a new dome washer. Yours is flattened. Yes, a slightly thicker sprocket will make up for a worn dome washer, but the sprocket is not the cause. It would be like milling a cylinder head to make up for bad compression rings.

Second is the countershaft lip seal: This is a sliding seal - the seal being stationery and the shaft/bushing spinning. KTM has a very good design here in that they have used a hardened steel bushing to minimize wear from the seal. Do not begin changing this seal unless you have first ruled out the O-ring issue described above.