Julian’s winter bike

Julian’s winter bike

My winter bike has served me exceptionally well – now four years old, it is pretty much all I ride from November to April, for errands and training, then once the weather gets better I still use it any time I need to carry or fetch stuff. I did a similar build a couple of years ago, then Julian asked me to build him one. But technologies have moved on a little – tubeless tires make a lot of sense for this type of bike, and Julian was also keen to try the Di2 system for the Alfine hub.

First the geometry – I had the fit information, but then had to work with the rest of the numbers to ensure toe clearance with fenders, and heel clearance for panniers, whilst still maintaining good handling. With this figured out, the next issue was combining the Alfine Di2 with the Gates belt drive – as standard the belt and the motor unit are not compatible, but with a little help from my friends at Co-motion, a solution was arrived at. I machined a split dropout for installing the belt, and used a Niner EBB for tensioning.

The rear of the frame includes an integrated pannier rack, that keeps the panniers low and tucked in for better handling. The right side also has a mount for the Knog lock. The rear brake caliper is tucked above the chainstay, with the cable run internally, and the Di2 wires are also all internal, with the battery in the seatpost (charged from the port on the handlebar display unit).

Components were chosen to match the stealth color scheme, and to help keep the weight down – complete ready to ride as shown the weight is 22lbs.


  1. Beautiful bike! Two questions:
    – I’m curious as to how the Di2 system performs relative to the standard Alfine setup. It seems to add a lot of complexity (battery, LED dashboard, extra cables, extra weight), and it’s not clear to me what “problem” it solves. Do you feel the faster shift speed justifies the extra complexity?
    – I notice you use cable disc breaks. Why do you prefer them to hydraulic disc breaks?

    • Hi John, I was a bit skeptical about the need for Di2 with Alfine too, but now having set up a few bikes I ‘get’ it a bit more. With the electric motor unit the shifting can never go out of adjustment. So there is no need to worry about cable tension, or keeping the cables clean and lubricated. Then what really makes it good is pairing it with Shimano’s R785 hydraulic Di2 levers/brakes (I wasn’t able to do this on Julian’s bike as the brakes hadn’t been released yet – see Richard’s similar build for the latest version) – then we have two sets of buttons that can be programmed as required. So either you can shift both directions with either hand. Or both right buttons can be set for up and both left buttons for down, meaning super easy shifting with bulky winter gloves. The gear indicator is a nice feature that the cable shifter doesn’t have too.

  2. Hey there,

    Like this build, but wondering what your winters are like. Are the roads filled with crap and super salty? Or is it just wet out? I am deciding whether to do an alfine di2 build for my winter road coming up…

    • Hi Matti,

      Winters here in Oregon are wet and some of the roads are pretty dirty. I have been using my Alfine bike for six years with little to no maintenance. We don’t have salt on the roads though. Julian is based on the East coast, and hasn’t reported any issues with the harsher road conditions there. I think the Alfine hub is a great choice for any sort of winter road bike.


  3. Hey I noticed you stated that the motor unit was not compatible with the gates belt drive system and then mentioned you had to split the dropout. Did you mean that the belt drive system was not compatible with the frame or the actual alfine di2 setup? I am building up a belt drive kona unit and was hoping to use it with the di2 alfine. Will this require any modifications to the drive train itself? (Excluding seat stay split to accommodate the belt)


    • Hi Alex – at the time I built Julian’s bike, Gates did not make a cog suitable for the Alfine Di2 hub. It requires a larger cog (28T) with an offset to the inside (which they do now produce). I used a prototype cog made by Co-motion that required me to make a few additional modifications to make enough space for the belt behind the motor unit. The new offset cog sits quite far inboard, so in order to get a straight belt line it requires room at the chainstay behind the BB for the beltring to also be spaced suitably inboard. Hope this helps,

      • Thanks for the quick reply, Rob. On that note, are you aware of any way I could insure gates compatibility with my frame? Should I install a similar size chainring and check the clearance between it and the chainstay? I would assume that the center track front ring’s teeth are centered on the ring and not spaced either way so I should be able to get a good idea of compatibility?

  4. hey, really a beauty of a bike! everything is so clean and mounted perfectly, the work of a professional!
    could you tell me what number of teeth you used for your belt drive (cog and crank) ? im building up a similar bike (gates drivetrain and alfine hub) and i want to make sure to have enough gears for even going up a mountain pass etc.

    • Hi Sebastien,
      With the Di2 motor unit, you only have the choice of a 28T rear sprocket (which is offset to the inside to clear the motor). On this build this is paired with a 55T front ring.
      Happy riding!

      • thanks!
        i guess the battery is hidden in the seatpost, how did you fix it in there?

  5. Just lovely… and what rims are those I wonder?

    • Thanks! Those are de-badged NoTubes Alpha 340s.


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