Building the Bike

Three years ago I wanted a 29er (29" wheels) and decided to buy a Specialized Stumpjumper Comp 29er. After riding the bike for awhile, I felt like I didn't really need all 27 speeds so I removed two of the front chain rings leaving just the middle ring. This resulted in the bike having only 9 speeds. For two seasons I raced the 1x9 setup sucessfully in the WORS series. Then last year I started experimenting on training rides using only one gear. I found that I was just as fast as when using the 9 speed setup. So this spring I decided to turn the bike into a true single speed.

The first problem is dropouts, those slots that the rear axial fits into, are usually vertical and so you can not adjust the chair tension by moving the rear wheel forward or rearward. However on the Comp 29er the dropouts , although vertical, are adjustable so you can slide them to adjust the chair tension. This made the conversion easy.

I bought a conversion kit for the rear wheel that consisted of a set of spacers, a lock ring and a cog that replaced the 9 speed cog. I also bought a new chain opting for a single speed chain which is wider, stronger and has less side flex than a 9 speed chain. Then I bought a single speed 34 tooth chain ring for the front that had no pins or ramps, devices that aid the deraillier in changing from one ring to another. Finally, I purchased a chain guide for the front ring from Mountain Racing Products (MRP) to help insure that the chain did not derail. The total cost was about $150.

The conversion took about 45 minutes to complete. The two things you must be careful of are: First, the rear cog should be directly in line with the chain ring. This can be accomplished by carefully sighting down the cog and the chain ring and adjusting the various spacers provided in the conversion kit. Second, you must adjust the chain tension so that the chain is not loose and flopping around and not so tight as to put the wheel in a bind. This will take a few minutes of experimenting but is fairly easy.

Now the bike is ready and the fun begins.

Mike