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Xi2, anyone? Hacking Shimano's electronic gears for the Three Peaks

Vin Cox takes a stanley knife to the Di2 cables and a sharp eye to ebay to knock up a very interesting three peaks bike

I was looking for a bike to ride the Three Peaks Cyclocross even on, something a bit different. Using ideas from the Fairwheel bikes forum on hacking Dura Ace Di2 gears I saw the possibility to bypass the stock Dura Ace shift/brake lever. The advantages of that are:

1) Not needing to buy expensive (~£500) brake levers.
2) Having free choice to use alternative braking systems, hydraulic for example.
3) Running a single chainring for cyclo-cross without having non-functional buttons on the left shifter.

I then used my free choice of brakes to go wild; seeking out old stock Magura’s HS77 levers. This lever was made over a decade ago as a road hydraulic brake set. It was rim based and didn’t have integrated shifters, so offered few advantages and required too much sacrifice to be a successful product at the time. Now it can be partnered with electric gear shift buttons and linked to disc callipers, these levers are the business!

Cut the blue wire

The gears: This was very very simple, but quite scary. I sliced through some expensive Dura Ace cables and spliced the wires together by twisting/soldering/heat shrinking/taping. The wires heading from the front wiring harness to the shifters were where the action happened, I cut off an dead-ended the left one, then exposed the delicate wires of the right hand one.

The right hand shifter wire has four cores; red, black, blue, and green. Blue was cut out as it’s for the front mech’. Then the red, black and green (red +, black -) were spliced onto exposed wires coming from some stock Dura Ace Di2 sprint shifters. And Voila! – bypass done (and guarantee voided!). I’ve also stuck two membrane switches to the centre of the handlebars which will eventually be spliced into the gear change circuit so I can change gear from wherever I’m gripping.  For now those switches are just along for the ride, which is no bother as they are only a couple of grams.

The brakes: It took a lot of research, but eventually I found that Magura HS77 and HS66 road bike brake-sets (for road and touring/cyclo-cross respectively) could be attached to Magura Julie disc callipers (pre 2006 mnon-HP models). Amazingly, I got new old stock of all these components via ebay.

The bike

I’m a Genesis Bikes rider. They have a bike (the Day-one Alfine 11) which is effectively my signature model. But for this project I thought it would be fun to look after myself. I favoured a different side of my cycling personality; the pure racy side, with none of my practical, touring or retro mimpulses. I bought the carbon frame direct from a Chinese factory and ported over most of my favourite kit from other bikes. The wheels are de-badged Mavic crossmax 29er discs. The seatpost is a USE suspension model (worth the weight penalty in my opinion). Cranks are SRAM Red with Time pedals on their tips. Steering is via short and shallow Specialized carbon bars.

I’m very pleased with the end result. With the shifting and brakes I have achieved something which only demo products from the likes of Colonago can do at the moment, and the whole bike is very fast, light, stiff, and sleek. There’s a niggling feeling that this isn’t really “me” though – At heart I’m a titanium or steel and leather kinda guy, not plastic, and maybe I don’t want a battery to change gear for me. I might still swap the saddle to a titanium Brookes Swallow and put on some leather bar tape to help me feel at home. I can’t ride this bike at anything other than races and feel comfy. But at a race, it totally rocks!

This gear/brake setup should be very low maintenance. The hydraulics and electrics are sealed systems which are impervious to dirt and wetness.

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