Rob English has been featured here before for his sweet custom builds (here and here, for example), and we’ve even teased this particular bike. Called the English Cycles Di2 Special, it takes stealth integration to the next level. Here’s the foreword:

“It always seemed that the control box was an afterthought, being cable-tied to the brake cables. So I made a custom stem to house it underneath. By also making an ‘upside down’ headset arrangement, such that the steerer is part of the stem and bolts into the fork crown, I was able to run the Di2 cables completely inside from the stem to the derailleurs. Then of course the battery needed to be hidden too…”

Curious? Sneak past the break and see how it all came together…

Straight on, there’s virtually no indication this is a Di2 bike. No visible battery. No visible controller box. No visible wires.

The battery uses Icarus’ custom internal battery with micro-USB charging port, and the port is cleanly integrated directly into the frame. The battery is about half the weight as 50% more capacity than the stock power unit.

Internal wire routing through the chain stays is now pretty common. Here’s where things get trick:

Rather than leave the control box zip tied to the brake cables, Rob fabricated a custom stem to hold it flush on the underside. Controls are still accessible, and wires are then run directly through the stem into the frame.

To make this work, the stem and steerer tube are one piece and the fork clamps to it at the bottom. It essentially uses an upside down Aheadset nut to tighten the fork and stem/steerer into the the headset, which is tightened into place from under the fork crown. Once that’s tight, the front brake is attached using a shortened bolt that, rather than running through the entire fork crown like normal, tightens up against a curved washer on the inside front wall of the fork.

The steerer tube has a cut out that’s smoothed edges to funnel the wires into the downtube. The hole allows the bar to rotate 90º, at which point it would hit the frame and stop anyway. Rob says the real stress points are where the steerer tube interfaces with the headset, so the hole doesn’t diminish the structural integrity of the system and that he thickened up the ends of the steerer tube, too.

About the frame, Rob had this to say:

“The frame features a Columbus aero downtube, custom butted and ovalized seattube, my signature skinny wishbone seatstays and True Temper S3 chainstays. Retro Sweet Wings steel cranks complete the steel theme, but the bike still comes in under 15lbs.”

This bike’s been delivered to its owner after spending a few days in Fair Wheel Bike’s showroom. Now we just get to wait and see what he comes up with for NAHBS 2012!