Final Drive Assembly Tips!

Final Drive Question: 

Hi. I am currently looking into building a chopper and have been doing quite a lot of research. Your site is VERY informative and the tips that you give. I do however have one question, when fitting a wide tire, how do you sort the final drive? For example, the chain or belt. From what I have seen you have to offset the transmission, does this effect the primary drive and engine? Do you have to shift the motor to one side? As I cannot understand how this works, and help or advice would be greatly appreciated.

Best Regards

Billy, UK

Final Drive Answer: 

Hello Billy,

Regarding final drive, it is important to determine how and where your chain and belt will reside.  Some bike frames have a bump out specifically to allow space for the chain or belt. It is a custom chopper so it is totally up to the builder to decide what is aesthetically pleasing to him.

I am not sure if you have a welding jig or not for your bike frame, but this is the easiest way to make sure that everything will fit and function properly. I recommend getting the rear two plates set at the width that you need and then try to lay out the bent tubes. Don't weld anything yet. You should clamp for now and measure to see how everything will fit.  

Some people use tack welds which can easily be broken if the spacing is not correct.  This will allow you to make sure that all of the important components will fit and function properly. You need to make sure that the engine, transmission engage and meet up properly. Also the belt/chain need to meet up with the rear tire and drive the wheel correctly. 

There really is no set procedure for this since it is a custom bike and every bike is unique. Thanks again for your interest and feel free to let us know with any other questions or concerns.

This article on wide tire motorcycles might provide a little more help. And this conversion kit article may shed some light as well. has a brief article on final-drive chain assembly.