Gabriele Boasso, Mechanical Designer and founder of Components Bike Design, has revealed images of their concept stem with three piece design. Merely a concept with 3D printed prototypes for now, this unusual looking stem takes a different approach to clamping the steerer tube. Let’s take a closer look to figure out what’s going on here.

Components Bike Design Concept Stem


The three piece stem is composed of a face plate, a central piece that cups both the handlebar and the steerer tube, and a second “face plate” style piece that bolts into the central piece to clamp the steerer.

Componentsbikedesign prototype stem concept Gabrielle Boasso three piece stem mtb central adjustable reach

The intention with this modular design is apparently to allow riders to swap out the central piece when they want to change the reach, rather than swapping to a different stem entirely.

three piece stem mtb concept prototype design adjustable reach

Before we discuss function, my first thoughts are about how convenient this might actually be. First of all, to swap out the central piece, you’ll need to unscrew eight bolts, as opposed to the 6 bolts you need to unscrew when changing a traditional stem.

Componentsbikedesign prototype stem concept Gabrielle Boasso prototype concept mtb stem three piece lightweight design

The reach of the prototype stem shown here is 32mm. Though most brands aimed at trail and enduro riding offer just a 35mm or 50mm option, there are a small number of brands out there collectively offering just about every length in between. Plus, a few offer even shorter options such as the Pacenti P-Dent, though this is solely compatible their indented handlebar.

three piece stem mountain biking 32mm reach

The design pictured has us wondering whether they are planning on offering a multitude of central pieces of differing lengths, in order to allow riders to select the exact reach that is best for them and their bike? Anyone for trialing reach in 1mm increments? Given the number of options already offered on the market, this would seem unlikely.

Componentsbikedesign prototype stem concept Gabrielle Boasso (2)

The 4 bolts connecting the central piece to the rear plate are oriented in the direction of the bike’s travel – forwards, instead of across the ways like we see on traditional stems. This calls into question how strong the system is laterally in comparison to a traditional stem. Will those bolts experience greater forces when cornering? Will they be strong enough to withstand said forces? Will the headset hold its adjustment without full contact surfaces around the steerer tube clamp? I’m no mechanical engineer so I’ll reserve judgement.

prototype-3-piece-stem-mtb-32mm-reach-3d printed

Details are thin on the ground at this stage. Gabriele’s plan now is to optimize the design from a structural point of view and to make a titanium model. It is undecided as to whether the stem will be made from aluminium or titanium, but the bolts will be titanium M5.

It is said that the front and rear plates will be customizable with the rider’s team logo or a specific sponsor, for example. Prototypes thus far have been made using ABS 3D printing.

Seatpost clamp with CO2 storage

Gabriele Boasso’s second concept product for cycling is a seatpost clamp that can carry a CO2 canister. It’s good to see product designers innovating in the space of on-bike storage. It’s a great freedom to be able to ride packless, so the more trailside essentials I can fit on my bike the better.

seat-clamp-co2-storage-components-bike-design-on bike storage solutions canister

The clamp is the traditional design with one bolt clamping the aluminium piece around the top of the seat tube. The difference here is the addition of a thread to accommodate a CO2 canister.

I carry a spare CO2 canister on a frame strap, and I tape the threads to keep them clean for ease of use when I need it quickly. This seat clamp storage design seems like it would hold a canister securely and keep the threads clean at the same time. That said, i’m not convinced that everyone would be happy to store pressurized gas underneath their saddle.

For more on Gabriele’s designs, you can follow ComponetsBikeDesign on LinkedIn here.


  1. preachingpedals on

    90% of modern mountain bikers are happy to store pressurized gas under their saddle in the form of a dropper post…..

  2. -s on

    I’ll say it. The stem is dumb. If I have to switch stem lengths now, I have to disassemble the top cap, and any spacers that may be in the way, unbolt the stem, and then swap stems. This does not solve that issue so why would I want a potentially weaker (and heavier?) setup that is just as cumbersome to swap?

    This would only be effective if the clamp system would stay in place on the steerer tube.

  3. M. on

    They should call that stem the knee killer…

    …A genius idea to have an exchangeable stem that probably costs a lot more and takes more time to exchange than to just buy a second normal one.
    Anyways a stem in my opinion is “set and forget” so I dont know what issue they are trying to resolve. (Yes I know for XC a longer stem is a bit nicer, but you’d need to compensate with narrower bars or a shorter top tube, and personally would not even bother to swap stems depending on the trail I’m going to ride).

    The CO2 seatpostclamp is quite cool though. You mentioned not many might be happy to have it underneath their saddle, but most people have it directly under their saddle in a saddle bag, instead of 30cm lower.

  4. Josh on

    That stem is terrible. If you don’t know why you should have full contact around the headset cup, you’ll probably design parts with multiple likely failure points… Like that thing. It’s just another “clever” design instead of actual good engineering.

  5. Dane on

    It will be an interesting event when you bump the CO2 canister hard enough to break the threaded end off. You had might as well put a CushCore tire lever handle over it.

  6. Michael Shallcross on

    I don’t like it. This would only be good for test rides, figuring out what length is best for you.
    If I had a fitting business it may be good, to carry a little less weight, and metal around.
    In the end you’re going to buy something legit, or the customer wants.

    • GB on

      Thanks for the feedback they help us grow.
      it is a difficult area to crash in the falls and the thread is difficult to break, in the next steps there will be improvements in detail
      Thank you for comment.

  7. tiny tim on

    Not a new concept with the stem I had a Tioga Cube stem years ago it weighed a ton and was fiddly. This looks lighter but just as fiddly.

  8. Andres on

    This is clearly someone’s pet project, and that’s fine, but this person has a poor understanding of material and contact mechanics; this thing is riddled with sudden changes in cross section, convoluted load paths and insufficient contact area.

    They also aren’t very adept at designing for manufacturing; the amount of operations required to machine this part is silly.

    All in all I would say it’s best to steer clear of it.

    • GB on

      Thanks for the feedback they help us grow.

      I guess from your feedback you are an expert designer, so expert that certain concepts are created deliberately complicated to make them less repeatable by anyone, there is a difference between concept and final design. Obviously with garage technologies it is difficult to achieve everything ….
      With a 5-axle it could be simpler … 😉
      But I’m not sure do you know 5 axis or yes?

  9. GB on

    Good morning,
    thank you for the feedback which is always well accepted and helps to grow,
    in this regard I have been doing MTB xcm for 10 years and keeping a bottle of Co2 in my pocket I have never had these concerns. while repairing a tire during the race with dirty latex gloves, one more can on hand would have been useful, the hurrying is not always the way it should go


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