Shock eyelet bushings, which and why?

Just curious really as to what people use for eyelet bushings these days.

Old school is the metal type with red lining on the inside.

New is a polymer type, usually dark grey and no lining etc.

Which and why?

Currently on beige coloured plastic ones because that’s what came with the mounting hardware.
Other bike has red two part plastic ones on and they will be replaced with beige two part ones because that’s what I’ve got in the spares box.
The “why” is because that’s the ones I’ve got to hand generally, it doesn’t get much by the way of conscious thought!

The polymer ones wear quicker but the metal ones can wear the axle. So I would go polymer I think they are known as Igus bushings.

Yeah I’ve got plenty of both, was just curious as to whether one was better for certain things

I use the ones from offset bushings. The press in bit is a dark grey plastic sort of thing with a metal bar and bits either side. Seems ok generally – although my preference would be a bearing mount really.

although my preference would be a bearing mount really.

I removed the bearing setup on my Slayer to make swapping springs easier.

Out of interest, why bearing type?

Smoother/less friction and potentially harder wearing, which is useful at pivot points that experience a lot of rotation, like the top pivot of four bar bikes. But as we all know bearings even sealed are defeated by water!

I’ve always bought mine from offsetbushings.com (they do offset and standard), think they’re brass from memory. I treated myself to some expensive Ti ones from Burgtec once and never noticed the difference (apart from the price).

Polymer ones cos I don’t like the idea of metal on metal coating aside on such a small part, I’d rather sacrifice the poly than the axle, igus beige or the dark grey ones, I also don’t like the top hat style bushes n mounts and prefer steel over alloy for the pin like the Profin ones from Bounce or Merlin, quality and cheap win win, I’ve got bearings on one end of my shocks so that choice was made for me.

DU ones from EXT.

I removed the bearing setup on my Slayer to make swapping springs easier.

Out of interest, why bearing type?

they last longer without going clunky. On my aether 7 I went though a few at the linkage end and I wonder if the one at the bottom of my sentinel is on its way out now too. Got a couple of spare press in plastic bits so might change it after a couple more rides and see if it quietens it slightly – or whether the noise is just from the new back tyre being harder rubber.

Just swapped the Slayer back to bearings after this… The spring is happy, so no reason not to.

EXT/Geometron brass hardware and igus bushing on the KSL, minimal friction and there is no wear after a year.

G1 is on sphericals, which all bikes should have as shocks shouldn’t be side loaded.

<span style=”font-size: 0.8rem;”>For bushing setups, there are 3 general options.</span>

DU/DP4 steel backed PTFE bushings. Will generally run on most surfaces, and don’t really wear the hardware until they wear enough that dirt gets in, or you run them far too long and they wear through the PTFE coating.
For reference, DU (typically grey/black) is a dry bearing, in that it should be fitted without any lubrication, and lubrication may actually cause the lining to fail sooner. DP4 is a semi-dry bearing, and can be run either dry, or where there is intermittent lubrication. For fully wet applications, there are far better options.

Low friction polymer. These are typically beige. These are a compound that’s primarily aimed to run on ‘soft’ surfaces, such as aluminium. They’re a fairly soft bushing, but they also suffer more from moisture swelling, so tolerances need to be a bit on the looser side to avoid excess binding if they’re going to be submerged in water.

Heavy Duty polymer. Typically grey. Quite a hard compound, meaning they will wear soft materials quite quickly, but on something like steel, will last quite a long time. However steel will obviously rust, so will often be supplied with stainless hardware. Stainless isn’t as good, but is a reasonable compromise.

In terms of mounting hardware material.
Bare aluminium is the cheapest, but least durable. It’ll still last a reasonable time with a DU/DP4 bushing in low movement pivots.
Hard anodised aluminium (aka Genuine RS/Fox hardware kits) is more expensive, but quite durable in most applications.
Stainless steel is even more expensive, and is probably on par with anodised alu for durability, but avoids the need for hard anodising.
Brass is just used because it’s easy* to machine. It’s a bit more durable than bare alu, but no where near as durable as anodised/stainless.
I should also probably mention Soft Anodised alu, which is what any of the cheap chinese kits I’ve seen have been. It’s a very thin layer, and doesn’t give that much more wear resistance over bare alu.

To maximise hardware life, do your best to keep dirt out. Don’t go jet washing pivots, because most bushings, as soon as dirt/grit gets in, it’ll embed in the bushing material, turning it in to a bit sandpaper. Even the hardest of materials will quickly wear once grit is embedded in the bushing (Volvo buses discovered this with their foray into hardened steel stub pins running in polymer bushes. The pins wore out faster than the bushings, to the point the bushings were still pretty much unworn, yet the pins would have a 1+mm groove worn into them)

*easy in that brass is fairly soft so isn’t too hard on machines, it chip breaks easy, so deep hole drilling is pretty pain free, and you can machine it dry without any issues.
Alu on the other hand needs very good lubrication and swarf clearance or it’ll clog the drill, gall, ruin hole tolerances and often result in a snapped drill bit embedded in the bar.
Stainless is harder to work with, and although not as likely to clog a drill as alu, it is harder on machines and cutting edges, and fairly unforgiving if things aren’t running in good condition (due to it’s very poor heat conduction, it work hardens quite easily, which can very quickly compound problems)

In terms of bearings, there are two shock mounted options.

The small ones that will fit in place of a bushing and run on some quite small diameter hardware. The bearing loading on these, unless you really do make a feather appear heavy, is horrendous. All the weight is transferred through a couple ~1mm diameter needle rollers, so they quite quickly fret the bearing surfaces.

The larger externally mounted bearings. Fox supply these, and they are a pretty good setup. The downside is they always seem to develop a creak caused by the cups moving in the shock eyelet. If you have these, along with a mysterious creak from the suspension, you’ll need to strip the cups out, and re-assemble with a fresh coat of grease.

Then there are the spherical bearing/bushing options.

Most well known is probably the older Cane Creek rose joints, but DT Swiss use a smaller polymer spherical setup.
Both work well, but I think Cane Creek have dropped theirs completely now in favour of more standard DU bushings.

In terms of which one to use.
If the pivot hardly moves, whatever fits and doesn’t rattle.
If it moves a lot, polymer of some form will usually be more durable, but chances are once the bushing has worn out enough to be noticed, the mounting hardware will also be worn. The one benefit of DU/DP4 bushings, is they don’t wear the hardware as much, so as long as you change them as soon you notice play, the hardware will usually last longer, so it mostly comes down to how often you can tolerate changing bushings.