Fourier’s Alloy Di2 Junction Box Mount

Fourier’s Alloy Di2 Junction Box Mount

Shimano’s electronic shifting components are wonderful, ground-breaking technology that offers virtually flawless shifting and reliability, together with great ergonomics. However, Shimano Di2 is not flawless and one of the few faults I can find is has to do with the junction box.
The current 11-speed Di2 (6870 and 9070), uses a junction box (designated by Shimano as the SM-EW90) that is uses a rubber strap to mount under your stem. On a base level, the strap is not the best looking way to mount that junction box and won’t even fit under most stems that are under 9cm in length (thus requiring a “jerry-rigged” mount elsewhere). On a more functional level, the straps need to be fairly tight, and this stresses the rubber strap, so it will presumably eventually fail. Maybe this is why Shimano includes two straps with the SM-EW90. The whole “rubber strap” Shimano Di2 mount seems more like a “stop-gap” than a clean solution.

Thankfully Fourier's Alloy Di2 Junction Box Mountthe creative engineers at Fouriers felt the same way about the Shimano Di2 junction box mount as I did and they did something about it. Fouriers is a Taiwan based manufacturer who makes a wide variety of parts for your bike, including stems, seatposts, handlebars, chainrings and junction box mounts. Fouriers has developed a clever alloy junction box mount that goes around the steerer tube, below the stem (taking the place of 2.5 mm worth of headset steerer spacers).

The Fourier’s mount is fabricated out of 6061 aluminum and shows a fine degree of workmanship, so it should stand up to long-term use. The fit of the junction box is snug, and there is a metal spring that provides a firm grip that assures that the junction box will not come adrift on a rough road. The result is a solid, alloy mount for your Di2 box, eliminating that rubber strap around your stem. Looking at the photos, which mount would you prefer? I personally prefer the Fouriers Di2 mount on the right.

Shimano Rubber Strap Di2 Junction Box Mount on BikeFourier's Alloy Di2 Junction Box Mount on Bike

Whether you have a challenging Di2 junction box mount situation due to a short stem length or an already busy cockpit, Fouriers provides a simple and solid solution. Heck, even if you have plenty of room to use the rubber strap mount, the Fouriers mount is worth considering as it is a cleaner and more solid way to mount the junction box. Why Shimano has not come up with something like this I have no idea. Anyway, the Fouriers Di2 junction boxes is available in 6 degree and 17 degree angles, and a variety of lengths, so it should be easy to accommodate pretty much any cockpit using a conventional stem with spacers between the bearing and the stem. Clean up the cockpit of your Di2 equipped bike, and get rid of that unsightly rubber strap!

Contact us to arrange installation of an alloy Fourier’s Di2 mount or to order one.

About Jim

After almost thirty years as an attorney, Jim became the service manager at Fit Werx in Vermont. He held this post for almost ten years. Having retired in 2019, Jim still likes riding, working on and writing about bikes and bike equipment.


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6 Responses to Fourier’s Alloy Di2 Junction Box Mount
  • Alan Bailey

    What angle stem and what angle mount are in the pictures above?

    • Ian

      We’re not 100% sure on the stem angle, but it is most likely a -6 degree. The mount is also a -6 degree.

  • Kent

    Do you know if Fourier can make a 5mm height instead of their standard 2.5mm height? My titanium spacer is currently 10mm and unfortunately Moots doesn’t make a 2.5mm titanium spacer with special anodizing. My stem height is perfect as is, so I don’t want to sacrifice the ride for an accessory that changes my position. Thank you.

    • Ian

      We are not aware of a Fourier mount that offers more height than the standard. You could potentially have a machine shop cut your existing titanium spacer down to 2.5mm. Hope this helps.

  • Bert

    Howe do I attach the Di2 junction box to the Fourier mount.
    It did not came with antique instructions.

    • Ian

      The top of your junction box should have a slot with a little nub next to it. On the Fourier mount, just slide the junction box slot onto the bottom of the L of the Fourier and the metal clip should engage the nub to lock it into place. Please give us a call at 802-496-7570 if this doesn’t make sense.

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