Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In

Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In



In Deep – Insider Trading

Your dropper post cartridge was probably manufactured by a company you’ve never heard of. And that’s a good thing.

Lock Icon

Unlock this article and more benefits with 60% off.

Already have an Outside Account? Sign in

Outside+ Logo

60% Off Outside+.
$4.99/month $1.99/month*

Get the one subscription to fuel all your adventures.

  • Map your next adventure with our premium GPS apps: Gaia GPS Premium and Trailforks Pro.
  • Read unlimited digital content from 15+ brands, including Outside Magazine, Triathlete, Ski, Trail Runner, and VeloNews.
  • Watch 600+ hours of endurance challenges, cycling and skiing action, and travel documentaries.
  • Learn from the pros with expert-led online courses.
Join Outside+

*Outside memberships are billed annually. You may cancel your membership at anytime, but no refunds will be issued for payments already made. Upon cancellation, you will have access to your membership through the end of your paid year. More Details

The following story first appeared in the fall 2021 print issue of Beta. To get print, sign up to be a Beta Pass or Outside+ member. Membership details HERE.

This is a surprisingly touchy subject. As I was reaching out to dropper post manufacturers, a few were pretty tightlipped about their cartridges. Some actually declined to comment altogether. As if it needs to be a secret that not every part inside every dropper post was designed and manufactured in-house. Maybe that would undermine our belief in the boot-strap ingenuity it takes to make bike parts. Or maybe, since Fox, RockShox and BikeYoke make their internals from scratch, why shouldn’t everyone else?

Well, here’s the thing: Fox and RockShox have been designing seals and valves and air springs for decades. And BikeYoke is German. These are not your typical dropper manufacturers. They would only ever build their posts from the ground up. The brands who choose not to are no less worthy. If this were almost any other product, we wouldn’t think twice. Your computer relies on countless prefab chips, your car is lousy with third-party components, and your bike’s frame was probably contracted out by the brand printed on its downtube.

Of course, these arrangements span a wide spectrum, from off- the-shelf to custom-made, and dropper cartridges are no different. If a brand has a specific vision for their post’s chassis, they have to also maintain some control over what is inside it. In the case of OneUp, both are produced under the same roof by a dropper post manufac- turer in Taiwan. Because this factory already produces everything you would need to make a dropper post, OneUp was able to take a hybrid approach.

“Almost every component in our dropper post and cartridge is designed by us,” says Jonathan Staples, owner/engineer at OneUp. “[But] we do use off-the-shelf seals, o-rings and raw forgings.” OneUp has even patented many of the designs they’ve conceived in this sandbox, so they will become exclusive to OneUp. It’s a unique arrangement, especially considering that the bulk of the posts that come out of that factory don’t carry OneUp’s name, but OneUp wouldn’t hint at who they are.

That was a theme among the brands I spoke with. One of the first I could get to talk was PNW, and according to CMO Todd Cannatelli, PNW’s cartridge supplier is “one of the largest dropper post manufac- turers in the world,” and they have a similar back and forth relationship on design. “We have a kids’ dropper post, and we worked with the manufacturer to get lighter action,” Cannatelli explains. A totally off- the-shelf cartridge ecosystem wouldn’t allow for that sort of product, but he notes that innovation also sometimes flows the other way. “They’re doing their own research and coming up with their own ideas and they’ll come to us with some solutions that we could potentially integrate.”

Cartridges are what cartridge manufacturers do, sometimes exclusively. Leveraging that sort of expertise is simply the most practical approach to solving one of the most complex problems in moun- tain-bike component design. “We looked into what it would take to manufacture our own system,” Cannatelli says. “With tooling, testing and QC, it’d easily be twice the price of the post we produce now.” And the benefit of low-cost cartridges is twofold. Not only does it keep the overall dropper price low, it keeps repair costs low. Or, to put it differ- ently, replacement costs.

Dropper Post
(Photo: Anthony Smith)

“These cartridges aren’t user serviceable, and that’s by design,” says Cannatelli. “Giving users the ability to crack these things open and potentially not service or rebuild them correctly can cause all new problems.” And plenty of riders wouldn’t even want to bother anyway. The fact that, for example, you can take apart a BikeYoke Revive post, clean it, replace some o-rings, re-lube and re-assemble it is appealing to some of us, while spending $50 to $70 and just dropping in a new cartridge in 5 minutes is appealing to others.

And for the most part, those cartridges all look pretty similar. It can be hard to tell one from another, and it doesn’t help that most don’t have the manufacturer’s name printed on them. Most, except Wintek Suspension cartridges. These are inside several posts out there, including e*thirteen’s Vario dropper. But they’re also not totally off-the-shelf designs. As e*thirteen’s marketing and design guru, Con- nor Bondlow puts it, “We’ve tested samples of their available product and tweaked the specs to a certain degree. Our Vario post performs and functions differently than other brands that use a Wintek cartridge.” There is a suite of options available in actuation force, holding strength, diameter and, of course, length. But with the engineering already done, it frees designers to focus on the chassis. “Having a known quantity to design around allowed us to work on different keys and bushings,” Bondlow says. “It also allowed us to work through de- sign and testing a lot faster.”

And it’s no coincidence that the rise in dedicated third-party car- tridge manufacturers has happened alongside a drop in failure rate. We worry far less about our droppers now than we did in the early days. A wave of mechanically actuated options emerged during the dropper post’s awkward adolescence, one of which was even made, and later abandoned, by e*thirteen. “To use bad analogies and painful memo- ries … no need to reinvent the wheel when someone is producing a solid, proven product,” Bondlow reasons. “The mountain bike market in general has suffered from a lot of disappointing dropper posts … either flawed designs, or flawed manufacturing on solid designs.”

A very early example of this is the Crankbrothers Joplin. A licensed product from the now-defunct bike brand, Maverick, the Joplin was plagued with reliability issues. When Crankbrothers went back to the drawing board to release the mechanically actuated Kronolog four years later, its good intentions weren’t enough to sustain it, and after one more unique approach to actuating its release valve, the current Crankbrothers Highline uses a traditional bell-crank connected to none other than a Wintek cartridge. And to drive home the point that this is simply the way things are done, Crankbrothers pointed out that the Highline also uses Trelleborg sealing, Igus bearings and keys, and Jagwire cable and housing.

It takes a village, as they say. Long gone are the days when the au- teur framebuilder was mountain biking’s ultimate craftsman. And even then, the vast majority of the parts bolted to that frame were made by other folks. No lone eccentric genius could have given us the AXS de- railleur. As our industry has matured, specialized fields have emerged. It’s paved the way for things like speed-sensitive damping, recyclable carbon fiber, and dropper posts that last longer than a season. We should be proud.

From Fall 2021