Fork Bushing Burnishing and Why it Matters
- Matt Noble
- Mar 24
- 4 min read
Updated: Mar 30
Let's discuss something that can seriously transform your ride: bushing burnishing. Yeah, it sounds a bit technical, but trust me, this is one of those hidden gems that can take your MTB fork from "meh" to "mind-blowing."
Bushing Basics: Why They Matter
So, what's a bushing anyway? In your fork, bushings are essentially the sliding surfaces that guide the stanchions (those shiny tubes) as they move in and out of the lower. They're crucial for keeping everything aligned and smooth. Think of them like the bearings in your wheels but for your fork's travel.
Tight vs. Loose: Finding That Sweet Spot
Now, here's the thing: you don't want loose bushings out of the factory. The industry has experienced that in years gone by, and people didn't like the feeling of the headset being loose or as if their fork was about to fall off. Overly loose bushings can cause play, and play means knocking and a general lack of precision but very minimal friction. And still perfectly safe, but a bit alarming.
But tight bushings? That's a whole other problem. High friction, harshness, and poor grip are the telltale signs. Ideally, you want that "just right" Goldilocks zone.
Here's where it gets interesting. From the factory, tolerances can be… well, let's just say "variable." When cranking out thousands of forks, getting every single bushing perfectly sized is tough. Manufacturers often err on the side of slightly tight, thinking they'll "bed in" over time. The problem? You're stuck with a fork that feels stiff and unresponsive for months, maybe even years. You're fighting a losing battle with small bump sensitivity, the grip feels sketchy, and you're probably running some weird air pressure setup to compensate for all that extra friction.
Lubrication is Key: Motorex Supergliss 100K
You need proper lubrication to ensure those bushings are working their best. And I'm not talking about just any oil. I'm a huge fan of Motorex Supergliss 100K. This stuff is seriously clingy. It stays put even in the hottest conditions, ensuring your stanchions and bushings are always coated. Fox 20wt gold is also good stuff, but the Motorex is a step above it. If we’re talking viscosity, Motorex 100k is 100cst@40c; Fox Gold is 99cst@40c. Other oils? They tend to thin out when things get hot and settle at the fork's bottom, leaving the upper part less lubricated until it gets cycled. Not ideal.
My Journey Down the Bushing Rabbit Hole
I didn't stumble upon this by accident. I was riding a Manitou Mezzer, and while it was killer on big hits, the small bump sensitivity was just… off. It felt like the fork was riding high, and the grip was always a bit nervous. I'd feel a slight bind on fork slapper landing landings (a weird harshness when the front wheel touches down after the rear wheel has landed). I took the fork apart, and, man, those lowers barely moved. Even upside down, I had to force them. They should almost slide under their weight!
I contacted Manitou, but they didn't acknowledge the issue. So, being me, I decided to take matters into my own hands. I tried everything—making the air spring super slippery, lightening the compression tune and oil viscosity, and even messing with weird air pressure setups. It helped, but it wasn't perfect.
Finally, I bit the bullet and invested in a complete set of LABA 7 bushing burnishing tools. These are the real deal, covering stanchion sizes from 30, 32, 34, 35, 36, 37, 38 & 40mm (meaning it will work with all forks from Fox, Rockshox, Manitou, Ohlins, etc.), with four precise sizing increments: 0.04, 0.07, 0.10, and 0.13mm. The precision machining on these tools is insane.
And let me tell you, the difference was night and day. Even at the 0.03 size, the bushings were way too tight. I start by using some of the 100k lube on the tool before inserting it into the lowers to twist and rotate it to polish and size the bushings perfectly. After the next size increment, my fork now slides like butter. The small bump sensitivity is incredible, and the support and bump-eating abilities are off the charts. It's up there with the best, even compared to the EXT Era 2.1, and the mezzer takes the crown for a better-feeling fork. And that Manitou Dorado air spring? You can make it feel exactly how you want it with correctly sized bushings—pure, uninterrupted air spring rates.
Do I Recommend It? Absolutely!
Look, not every fork needs bushing burnishing. Some get lucky with perfectly sized bushings straight out of the box. But for most of us, dialing those bushings makes a massive difference in comfort, grip, and control. I've seen some crazy variations in bushing sizes, even within the same fork. I serviced a Pike recently, and all four bushings were different sizes; one side was very tight, and the other was loose. The rider said that turning one way would feel skittish, but it seemed ok when turning the other way! We had all bushings sized, and now it perfectly tracks everywhere.
So, if you're serious about your ride quality, bring your fork in and let us check your bushings with a 100-hour service. Passing a 0.04 size will bring most forks back to their intended baseline. More often than not, going up to 0.07 is where the magic generally happens. Going above that is used if you're looking to squeeze every second out of the clock with minimal friction for a race-only application, or in very problematic fork scenarios, we can go to the larger sizes. However, larger sizes decrease bushing longevity; mild knocking can be felt, and lower leg oil service intervals increase. You know, race bike things where performance over everything matters.
And if you’re looking for someone to make this happen, you know where to find me: matt@vincentspeedworks.com. Let's get your fork sliding like it should!