How to: Install RWC Needle Bearing Kit
I'm pretty nit-picky about my bikes and any noise, whether creaking BB, headsets, or drivetrains really bug me. So naturally I was upset when my shiny new SC Hightower LT developed an audible clunk. A quick search online on how to diagnose "strange noises" yields about a thousand different possibilities, so the only thing to do was to try to systematically isolate the issue myself. The headset and dropper post were pretty easy to rule out by performing the normal tests. Then, for a while I was convinced that the suspension pivot bearings were creaking, so I spent several hours cleaning and re-greasing all of the pivot axles in the rear suspension. It felt nice and clean, but the clunk was still present. So, after some further internet research I discovered that despite all the fancy technology that goes into modern mountain bikes, that almost all rear shocks still use a plastic bushing at its eyelets.
It turns out that these so called DU bushings produce a non-negligible amount of friction in the rear suspension and even worse, they wear out quickly and bind up which can produce an audible clunking noise. For certain frame designs, there is actually quite a bit of rotation of the rear shock relative to the frame, which is the case for lower eyelet on my bike.
The solution to this problem is to replace the plastic bushings with an actual bearing. RWC (real world cycling) has solved this problem by producing needle bearing kits that replace the stock DU bushings. For a bit of background, needle bearings are a great solution to this problem because they are relatively thin and are capable of supporting a greater load than standard ball bearings. Their website, for some confusing reason, is www.enduroforkseals.com and the kit I used is part number NBKRWC2185.
The following video is pretty much a video tutorial following the PDF directions provided online:
I hope this solves the problem for some of you who are chasing down bike noise issues. Happy riding!