Full Custom Pinion gearbox fat bike

This latest build was really quite a custom bike. My client has wanted a pinion bike for a long time (hates derailleurs) and finally decided he wanted a fat bike. The two go together great, since the fat bike is such a great multi-purpose, simple machine. Going Pinion with the platform makes the drivetrain enclosed, long lasting, and almost entirely maintenance free. Add a Gates Carbon belt drive to the mix, and you have a bike that is designed to go and go and go with very little needed to keep it going.

So needless to say, I was very excited about this build. Some highlights are:

  • Pinion C1.9XR gearbox. This gives my client a 568% gear range in 9 gears, making it lighter than the C1.12 (12 speed) with a wider gear range than 12-speed Eagle or XTR.
  • Trail forward fat bike geometry. The geometry we settled on makes this bike ideal for shredding singletrack and steeper riding. On the dirt, sand and rocks of the high desert and chossy mountain riding this will do a ton of, the geo is the perfect blend of aggressive, yet ride-all-day comfortable.
  • Fits 175mm dropper post with stealth routing.
  • Bent top tube for good standover on the varying terrain this bike will see.
  • Shortest possible chainstays with a Pinion gearbox thanks to heavy Pinion bridge modifications.
  • Gates Carbon Belt drive compatible with a stainless seatstay splitter.
  • Paragon sliding dropouts for perfect belt tension.
  • Whisky carbon fat fork to shed some weight.
  • Brazed on stainless headbadge.
  • Black decals for a super-stealth black on black downtube.

This is the third Pinion gearbox bike I’ve built, and I found some solutions to problems that are really challenging about the platform. The biggest is the Pinion bridge itself. The bridge is the part I weld into the frame that accepts the gearbox mounting bolts and is the “bridge” between the gearbox and the bike frame. The bridge as it comes from Pinion is extremely challenging to use, most specifically for off-road bike frames. Mitering chainstays to fit the odd W-shaped back side of the bridge is time consuming, and limits how many different chainstays you can use.

So for this build, I took a completely new approach. I milled the entire back side of the bridge off, and welded in a steel plate that has a nice flat surface for chainstays to land on. This not only saved me a tremendous amount of time, and made the chainstays stronger, but in future builds I can change the width and thickness of the plate depending on the application, further customizing how I integrate the Pinion gearbox. It was a game changer, to say the least.

This is also only the second frame I’ve sold in Matte Black, which surprises me. For how much people seem to love black bikes, I don’t get a request for this color often.

This bike was for a local client, so I’m excited to go on rides with him and see it in action on the trail.

For more information about ordering a custom Pinion bike of your own, check out our Custom Framebuilding page.


3 Replies to “Full Custom Pinion gearbox fat bike”

  1. I found the post on the Internet just now as I had sent a message on Instagram a bit earlier. I am very interested in a build

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