mountain bike suspension industry manufacturers collaborate on new metric sizing standards for rear shocks and frames

Just when you thought we were through with standards changes for a while, the industry has come together to introduce new metric sizing standards for rear shocks. The collaboration will affect frame manufacturers, as upcoming frames will need to be designed to work with specific eye-to-eye measurements and stroke lengths.

From initial conversations we’ve had with Rockshox, one of the big benefits to shock manufacturers is more standardization of offerings, which means they can better design, tune and manufacturer shocks around specific parameters rather than needing to create something new for each bike brand.

Cane Creek, DVO, Manitou, Rockshox, SR Suntour and X-Fusion are all on board. Bounce on down for some industry comments…


Trek’s DRCV shocks use a trunion mount rather than an eyelet, which could become more popular as shock engineers and frame manufacturers both try to gain space.

“Some manufacturers expect to see durability improvements. For us, it increases the available space for the IFP’s gas volume and damping piston designs,” says Manitou’s chief suspension engineer, Ed Kwaterski. “Others could have increased overlap between the shaft and air can’s bushings and rings – the further apart they are, the more laterally stiff the shock can be. While it the shock shouldn’t be carrying side loads, it could help in some cases. So, some of the sizing being discussed involves lengthening the eye-to-eye for a given stroke length. And it’ll reduce SKUs for all of the suspension brands because, for us anyway, we’re currently stocking more than 100 SKUs, which is ridiculous. This change will standardize the sizes offered and reduce the number of items required to be stocked.”

“It definitely allows for the designers to do more stuff with the shocks internally,” adds John Pelino, DVO’s general manager. “For a size like a 200×57, there’s zero room left over when that shock is at full compression, so you’re very limited as to what you can do with the damping. So switching to something like a 230×60 or 210×55 gives the engineers more room to develop the damping in the shock. The kinematics of the bike are where it’s really going to affect things the most, but it’s going to have to get bigger to work with the new crop of shocks under these updated standards.

“Trunion shocks will likely get more popular, which are shock canisters that put the air can’s mounting bolts on the side of the shock rather than adding length for an eyelet.”

Unfortunately, this does mean more shock sizes and SKUs for dealers or distributors to stock (or at least be aware of). But, the result should be better suspension.


  1. Aaron on

    Wait, so we’re standardizing to cut down SKUs, but wait that means more shock sizes and SKUs so that we can stock more SKUs? That doesn’t make sense, bike industry!

    • steve on

      This is 100% from SRAM,it’s just a BS way for them to try and steal spec from Fox. The consumers get the short end of the stick.

  2. HDManitoba on

    A bunch of this announcement is marketing fluff. Changing from imperial units to metric units does nothing to help or hurt performance or anything else. After all 1 inch = 25.4mm all the time so you can always convert unit of measure back and forth.

    What does help and is commented on in the text of this article but not the marketing press release is using longer length with shorter stroke. You can do this with or without the metric system.

    In fact, some bike companies have been doing this long eye-to-eye/short stroke for years. Of course most of the goofy, difficult to make sizes were done at the request of the bike companies in the first place even under objection from suspension makers. And then they just became a defacto available size.

    • steamed on

      Well, actually no. There are some US Companys who don’t give a shit.
      Stan’s NoTubes for example when producing rims with the ETRTO standard. Tolerences are so off, that Schwalbe has put warnings out to don’t use there Road Tubless Tires on NoTubes rims, because they could pop off.

  3. i on

    This kind of reads like an April fool, except it’s not funny enough to be obvious. ‘Industry comments’ without attribution, one saying it will increase SKUs, another saying it will decrease them. No details whatsoever on what ‘metric sizing’ even means – though on comment implies that 200x57mm is not ‘metric’ but that 230×60 or 210×55 somehow would be, another claiming that this will allow trunion mounts even though I believe Trek has a deal to not sell them to anyone else.

    Is this really 5 fairly small players plus Rock Shox saying “we’re going to make shocks for frames that don’t currently exist” ahead of Trek and Specialized asking for them?

    crappy reporting or an un-funny joke? Hard to say.

    • SA on

      The bikes aren’t on the market right now, sure, but they’re more than likely in development. Plus, any move away from imperial units is good.

    • mateo on

      It will be both more and less SKUs. Fewer different sizes being speced on new bikes, but an additional set of shocks for distributors/manufacturers to carry until the “old” sizes die off.

  4. ChrisS. on

    There is the one GLARINGly obvious producer of squishy things that is not on that list and another already fabricates in metric sizes in Sweden so no suprize there either.

  5. Ripnshread on

    Seems like an odd/marketing bs way of the “suspension industry” saying,

    We are going to be taking more space and giving you less freedom. Deal with it.

    Will prices be coming down? lol jk.

  6. Drew Diller on

    I learned a word today. It is spelled “trunnion”, two Ns in the middle.

    I was thinking of how the heck do I want to make my rocker arm middle bearing assembly, and what term would describe it? So I took a break, showed up here, and was like HEY that’s the term right there!

    Neat timing.

    Regarding the actual topic: well the engineering side of it kinda makes sense, but I totally grasp the frustration with “oh yay, another interface”.

    I wish we could stop calling things standard. How about “spec”? “Size”? “Interface”?

    When I used to work in software, at one point I had an office window where I watched construction professionals erect a building. They made a damn building with a dozen people faster than one hundred IT professionals could make a halfway decent website. While watching the construction workers, I knew THAT was what working with standards looked like.

  7. Smokestack on

    This is all in all good news. But like all things in this biz, the rate of change is faster than people’s abilities to accept it. From a manufacturing point, you want to offer as best of a product as possible, but there’s only so much you can do when a manufacturer wants x stroke in y length. Anybody remember the OG Rocky Mountain or Transition bikes? Things were hell on rear shocks. Things have gotten better for sure, from them and other brands, but they can be even more so. As to why Fox isn’t on this list, we’ve all seen how happy they are to offer the most ridiculous sizes and configurations to Specialized and Trek, to say nothing of proprietary designs for specific models. Why would they want to jeopardize that relationship and admit there are flaws in those design envelopes that need to be addressed?

  8. Icanusegoogle on

    If it’s a joke a lot of bike websites are running the same joke. From another site:

    ” ‘metric’ isn’t just a switch in listed dimensions, and this whole thing has little to do with metric versus imperial systems. “Metric,” as it’s referred to here, is actually a new set of sizes for rear shocks that have been agreed upon by suspension and frame manufacturers. That means new eye-to-eye and stroke measurements are coming soon, and, given the name, they’ll likely be in conveniently chosen increments of millimeters.”

  9. traildog on

    I hope this is a joke, because what they are saying is that instead of using existing parts to make a 216×57, which also solves all the problems mentioned, they want to create another problem for everyone. But I’m really trying not to care.

    They really make it hard to want to buy a new bike.


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