Enduro Shock Bearings
Most major suspension brands run DU coated bushes in their shock eyelets. In theory bushes are the best solution to this application, which sees high loads and not a lot of rotation. However, the reality is that a lot of people encounter problems with their shock eyelet bushes. Whether it’s a tendency to seize or develop play, they don’t tend to be a long lasting option—at least on some bikes.
Enduro Bearings offers an alternative with their needle roller bearing kits. For between $18 and $32 you get a cartridge roller bearing that matches the common 12.7mm shock eye diameter, as found on Fox, RockShox, Manitou and the newer X-Fusion shocks. Each kit is supplied with an inner shaft, spacers and wiper seals that are sized according to your requirements.
Mounting the needle bearings is no harder than replacing the stock bushings. You’ll either need a proper shock bush tool (around $50) or a vice with a selection of socket fittings to press out the old bushings and refit the needle rollers. Push the DU bush out, press in and centre the needle roller cartridge, grease it up, slip in the inner shaft with the seals and spacers, then refit to the bike. Replacing both DU bushes on my Fox RP23 shock only added 11g, so the weight difference is negligible.
Enduro needle roller bearings are said to last longer than the stock bushes and have less friction. In theory this reduction in friction should allow the suspension to move more freely, reducing the stiction in the whole system. Given the loads imposed when hitting bumps are so great, I didn’t think I’d be able to tell the difference with the needle rollers fitted. There’s already stiction from shock seals, swing arm pivots and linkage bearings—surely a small reduction in friction from the bushes would be lost in the bigger picture.
To get a better idea of the difference, and to ensure that I wasn’t relying wholly and solely on ride feel, I devised a couple of basic tests. First up, I clamped the shock eye in a vice and used some scales to measure the force required to make the unit turn. My used bushes took a 250-275g load to get them moving. The needle rollers moved with next to no resistance (0-20g). While that’s great, I was still confident that friction in other areas of the suspension system would override this and make the difference undetectable.
For the second test I had the shock mounted to the bike and took the valve core out so the air spring was removed from the equation. Then I gently placed a 6kg weight on the saddle. With the standard bushes fitted, the suspension compressed 8mm. Using the Enduro Bearings, the suspension just kept sinking—it dropped by 90mm (around 70% of the available travel). So it appeared the lower shock eye friction was measurable above the shock damping, seal friction and other forces that need to be overcome.
Next up I should have been out on the trail but there were a few hiccups that delayed this. The needle rollers had a noticeable amount of play—they felt like worn DU bushes with a ‘knock’ whenever you picked the bike up by the saddle. Enduro Bearings recently had to redo their tooling for the shock eye bearings and they are having tolerance problems. The local distributor is fully aware of these issues and now has their own quality control checks in place to ensure that any dud bearings are picked up. So after a bit of messing around and refitting new bearings, I was finally in action.
In riding I felt the needle roller bearings gave the suspension better initial sensitivity and suppleness over small bumps. I couldn’t feel any difference on drops and bigger hits but there was a definite improvement over small trail chatter—the whole system just felt a little smoother.
Suspension Swings & Roundabouts