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

by Vin Cox   September 27, 2012  

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.

17 user comments

Oldest firstNewest firstBest rated

*applause*

Bez's picture

posted by Bez [432 posts]
27th September 2012 - 11:41

5 Likes

Brilliant!! I love it when people start messing about with things like di2. If i did anything like that the bike would explode or go backwards!

Benjamin Hall's picture

posted by Benjamin Hall [64 posts]
27th September 2012 - 11:54

2 Likes

cool stuff Vin. What ratios are you using for the single ring setup? Just curious as I have a 1x9 on my cross bike.

joemmo's picture

posted by joemmo [898 posts]
27th September 2012 - 12:05

4 Likes

What's in that saddle bag? All of the leftover parts? It must double the weight of the bike.

tonyb

posted by tbyrne [13 posts]
27th September 2012 - 12:08

7 Likes

Respect!

alotronic's picture

posted by alotronic [295 posts]
27th September 2012 - 12:16

4 Likes

Very cool, I'd love to see some more close up pics of the shifters and stuff!

posted by acjim [29 posts]
27th September 2012 - 12:28

3 Likes

I've been considering one of these chinese frames, but have read some horror stories. If you trust it for Cyclo-cross then surely one would be fine taking a heavy pounding on the road?

posted by karlowen [65 posts]
27th September 2012 - 12:30

5 Likes

Applause Vin'll Fix It

mingmong's picture

posted by mingmong [212 posts]
27th September 2012 - 12:50

6 Likes

acjim wrote:
Very cool, I'd love to see some more close up pics of the shifters and stuff!

hoping to get some more pics from Vin of the bike, so stay tuned

Dave Atkinson's picture

posted by Dave Atkinson [7490 posts]
27th September 2012 - 13:57

3 Likes

joemmo wrote:
cool stuff Vin. What ratios are you using for the single ring setup? Just curious as I have a 1x9 on my cross bike.

Ratios: 11-28 cassette with a 34 chainring for the 3 Peaks. I’ll swap up to a 36 chainring for regular ‘cross racing (39 if I ever find form again).
The Dura Ace mech’ can easily cope with more than the 27 teeth it’s officially rated at. The chain just has to be not too slack and the screw to adjust the main body’s angle has to be tightened down.

Vin Cox

posted by Vin Cox [49 posts]
27th September 2012 - 14:55

6 Likes

Loving it Vin. Will give it a quick 'weigh' on Sunday - looks ace!

minnellium's picture

posted by minnellium [79 posts]
27th September 2012 - 15:11

5 Likes

karlowen wrote:
I've been considering one of these chinese frames, but have read some horror stories. If you trust it for Cyclo-cross then surely one would be fine taking a heavy pounding on the road?

I chose the design carefully and found many Chinese factories make any one design of carbon frame (I guess they all buy from a more limited supply of moulds). I then picked the factory based on clarity and promptness of communication, careful viewing of their sample photos, interpretation of their technical specs, and of course price. There’s still quite some risk and time delay involved in buying a bike like this, so I wouldn’t recommend it for many people, but it was a good experience for me.
Like the look of the frame I chose? John Holmes at Cyclo-cross Imports will be importing these bikes soon. That gives a buyer some protection and connection to a more local dealer who understands their sport and their needs better than a Chinese factory clerk.

Vin Cox

posted by Vin Cox [49 posts]
27th September 2012 - 15:14

6 Likes

Top work. That looks like a brutally rapid way to travel offroad.

andyspaceman's picture

posted by andyspaceman [232 posts]
27th September 2012 - 16:20

3 Likes

waiting for more photos.To see carbon parts.

posted by happynicky [1 posts]
28th September 2012 - 7:24

5 Likes

Nice, I hope the battery can survive the 3ft of water it will be going through on PyG lane

posted by Darthshearer [141 posts]
28th September 2012 - 8:16

6 Likes

Using HS66 levers is good but leaves you without an expansion chamber, so they will operate as a 'closed' system like old hope C2's. Not a problem for your typical CX race but could become an issue with the cold weather over winter. Hope it works out for you, would like to hear how it copes/coped with the race.

STATO's picture

posted by STATO [421 posts]
30th September 2012 - 18:44

3 Likes

It needs a sound chainset though Wink

minnellium's picture

posted by minnellium [79 posts]
1st October 2012 - 16:07

3 Likes