Domahidy Designs Domahidy Sliders

If you’ve been following Domahidy Designs on facebook lately, you may have noticed a few teasers popping up. The slow roll has included a few different shots of what appears to be a new mountain bike from Steve Domahidy. As the former co-founder of Niner Bikes, and designer of some noteworthy bikes, Steve has been selling his Domahidy Design bikes for a couple of years now and floated us a teaser along with a few new photos.

You’ll have to tune into Mountain Bike Radio for the full release, but if you read between the lines you can get a pretty good idea of what’s coming…

Domahidy Designs Domahidy Frame 2 Domahidy Designs Frame

Since releasing their first production titanium and steel mountain bikes, they’ve released a carbon road bike and now it looks like they’re going completely outside the box and into a… gear box? At first glance, the titanium-looking split chain stay wasn’t a big surprise since they already have that on their other hard-tails, but taking a closer look, something is up with that bottom bracket. After doing a little digging, I found the pic below with the Facebook tagline….

Domahidy Designs Domahidy Pinion

photos c. co Domahidy

I guess this gives up a lot of info on the new bike, but new boxes came today and I can’t wait to get the final pre-production bike built up! #piniongearbox #notasinglespeed #notelectric #singletrack #mountainbiking @carbondrive

Well, there you have it. It looks like a 12 speed, titanium framed, gearboxed belt-driven hardtail _____ bike. I want to say I see “fat” clearance but I’m not placing any bets just yet. (I’m secretly guessing a plus bike – 27+/29″?). You can catch the official announcement on the Mountain Bike Radio podcast on March 24th. Any other guesses as to what Domahidy is up to?

Pinion 12 speed gear box (2)

Pinion 12 speed gear box (7) Pinion 12 speed gear box (6)Pinion 12 speed gear box (5) Pinion 12 speed gear box (4)

We saw Pinion at Eurobike a couple of years ago that already had an 18-speed gearbox, but they came out with a 9 & 12 speed to reduce weight. Though still significantly heavier than a traditional high-end drivetrain, it takes a lot of weight off of the rear of the bike and puts it in the best place possible which is low and centered.

Pinion 1

Pinion 2

Another benefit is the gear range available on the 12-speed Pinion system verses a 1 X 11 and 2 X 10 is a bit broader (above diagram). Each gear is exactly 17.7% up or down from each other so you’ll always feel a consistent gear difference no matter what gear you’re going to. It’s also virtually a completely sealed system making it perfect for winter slush and you only have to do an oil-change once a year.

Pinion Gears

From the Pinion Website:



transmission type Spur gearing
Number of gears 12
Overall ratio 600 %
Gear steps 17,7% constant
Recommended ratio of
Rear Sprockets (21t/24t for example) to front
Gain ratio in 1st gear (21t/24t)/td> 1,82
Gain ratio in 12th gear (21t/24t) 0,3

Real gears refer to the gear steps of a bicycle transmission that can be optimally used. In derailleur gears, the skewed running of the chain leads to significant losses of efficiency. In addition, when there are two or three front sprockets there will be redundant, i.e. equivalent, gears. A 3×10 derailleur transmission, for example, actually only offers 14 or 15 real gears from this perspective.


Chain line with Pinion chain ring 54 mm
Maximum input torque 250 Nm
Axle standard Pinion splined shaft
Q-faktor 1 174 mm
Lubrication Splash lubrication
Oil type Pinion gearbox oil 2
Oil capacity 60 ml (2.0 oz)
Temperature range 5 °F to 104 °F


Oil change interval every 6.200 miles /
Once a year


  1. jbt on

    I’m not an expert on internal gear boxes, but someone here probably is…are the reasons they are not more commonly used the following, not in any order:

    1. Generally heavier
    2. More expensive
    3. Less able to handle torque loads in certain scenarios
    4. Less efficient

    I was always told that the last attribute, #4 was primarily the reason, in other words, there’s a fair amount of efficiency lost within the transmission mechanism. In a car it doesn’t so much matter, but under human power that lost efficiency really adds up. Again, I’d really like to know some of the factors behind lack of adoption because the concept seems great (no external der, in theory the potential for a CVT-like range, belt drive, no chain maintenance, etc.).

    • Francois on

      About #4: Rohloff claims that their rear hub has an efficiency similar to a derailleur system, for most gear ratios (figure 3, 4, and 5 And that’s assuming a clean system (I’ve seen studies that showed ~2% loss with a dirty rear derailleur pulley, but I don’t know how dirty we’re talking about).
      I don’t have data about gear boxes in the bottom bracket, but it should be similar since it’s also a planetary gear box (assuming the same manufacturing quality).

      About #3: I’m not aware of problems with high torques. I know some component manufacturers require frame builders to show that the rear triangle of their frame is stiff enough for their systems (maybe Gates belt also require that, I’m not sure).

  2. Bill on

    @jbt – What manufacturer in their right mind would invest in making the existing tech any better, when it has those drawbacks now? I think it can get better – maybe even compete with gears eventually, but that improvement isn’t free, and there’s just no market to justify dumping the research dollars in.

    Although, small builders making something really cool that other small builders copy, that eventually the big players invest in… that’s happened many times in this industry, so party on Mr. D…

  3. jbt on

    @bill, my question was actually are those the real drawbacks? I think Shimano has invested in Nexus, so someone from the big companies is or has worked on this. Meaning somewhere there is a perceived market that commanded or still commands investment.

  4. Andre on

    The efficiency of the Pinion gearbox lies around 1% to 2% percent below a derailleur drivetrain in optimal condition. Similar to a Rohloff, but even better because of the placement.
    Pinion is not a planetary drive its a spur-geared drive. Both engineers were developing Porsche gearboxes before.
    I use the drivetrain with a normal chain on a trailbike:

  5. Tim on

    Pinion gearboxes look really interesting. But… everyone should know they can use only an ISIS bottom bracket and the cranks that go with them. That means no high-zoot, lightweight carbon cranks.

    • jooo on

      Not sure where you got that idea from? It is nothing like ISIS. The bottom bracket spindle is integral to the gearbox and isn’t plagued by any of the bearing issues familiar to ISIS users. The cranks use a common preload and pinch bolt just like a whole bunch of other companies.

      The existing arms are fairly heavy but nothing excessive. Swiss company C8 are developing carbon replacements.

  6. Andre on

    @ Tim: Pinion has a special crank interface, there are only the pinion crankarms, no ISIS bottom bracket, its a complete capsuled system. I remember one company, that wanted to offer a pinion carbon crankarm:

    Best André

  7. drosser on

    I wish Pinion would establish a US distributor. The rumor is that Co-motion is ready to build bikes with Pinion gearboxes, but no warranty support is a deal-killer.

  8. clawhammer on

    I went from a Pinion back to a derailleur. I kind of have to for the next couple of months. (Sold the bike, waiting for the new frame..) After 1 day of riding I wanted my Pinion back. The weight is seriously a non issue in that location. I was very afraid the Pinion box would not be efficient, I was afraid it would leave me with a Nexus feeling, where 50% of leg-power is disappearing in the hub, that frustrated me a lot. Pinion feels extremely direct, what you pedal get’s on the ground, basically not having that weight or “wind up” in the rear really helps. I never had issues with it, in the 15000km traveled. Box went back for servicing last month, long overdue, part of the shifter mechanism evolved and all old boxes got a free upgrade. Box looked as new when it got back. April can’t come soon enough. 🙂

  9. Tim on

    clawhammer- what kind of rear hub do you use? Do you use a fixed hub?
    Sorry about the ISIS comment- the axles look a lot alike and my imagination must have fabricated that idea.


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