At the Bench: All Internal

The quest to eliminate cables from waving in the wind and muddying our air has been slow and fitful. No sooner had the world adopted “aero” brake levers than Shimano added new housings to the mix with their first generation of STI shifters. More recently, carbon fiber frames have allowed manufacturers to run ever increasing component controls through the frame rather than outside it. Sure, aerodynamics drove those first urges, but with hydraulic hoses and Di2 wires, routing them on the outside of the frame is a nonstarter because using zip ties to affix those items to the modern equivalent of a brazeon may work on mountain bike but it is the antithesis of aero.

Internal routing on bars has been around since the early 2000s with the first aero drop bars, but again, with the advent of Di2, running those fragile wires inside the bar rather than along it makes implicit sense.

But we can’t leave well enough alone. Some bikes are beginning to tackle the internal routing idea with a kind of totality that seems really cool—that is, until you being to grok just what has to take place in order to make the hose and wires reach their destinations.

My first inkling at what was headed our way came with a Shimano PRO bar that sported an oval opening at the rear of the clamp area. Though I could tell what it was meant to do, my state of disbelief that we were headed there forced me to ask the stupid question.

I’m in the midst of building an Allied Echo gravel bike and the only exposed hoses and wires occur right where they exit the frame on their way to their respective components. I estimate that it results in maybe 10 total inches of exposed hose and wire.

I’ll admit that at one point in time the thought of routing hose, wire or housing through a frame was intimidating. I’ve just taken the Coefficient RR bar that I just reviewed and repurposed it for the Echo because it is one of the only bars on the planet with a port at the back of the clamp area large enough in diameter to allow two hydraulic hoses and a Di2 wire to exit it.

The mental gymnastics (read: logic) required to figure out not just how to route the hoses and wires, but also which order in which to do everything required eight hours spread over two days to execute. And I’d never have pulled it off without the aid of Park Tool’s IR-2.

Shimano’s shifter harness features two wires that join together with a single lead that runs to the handlebar junction box. With the Coefficient RR, there is no getting the whole of the harness past the thin point in the drop, so it’s necessary to start at the port at the back of the clamp. Once the first lead reaches the junction box then it’s possible to run the leads to the exits for the control levers.

This would be where I complain that the actual plugs for Di2 wires are too damn long. Coaxing them around any turn, be it the at the top or in the hook is a recipe for manual hair loss. I took to using a water-based, uh, personal lubricant to ease the various plugs and Park Tool fixtures through the bar and yes, it really made a difference.

While the hydraulic hoses don’t have to travel as far, the hoses feature a stiffness the wires don’t suffer and their larger diameter makes them just as tough to negotiate through the bar.

Because either I’m crazy and nothing is too hard to tackle or because I live in Sonoma County where some of our descents are as steep as credit card interest, I went for the bonus round and chose to add a run of housing for a dropper post.

There wasn’t enough room at the clamp port, so it exits a different opening in the bar and will be routed externally to the badge on the frame. Beneath the badge is an opening in the frame the housing can enter.

This did force me to accept one concession. The shifter harness required an extension so that the wire would reach the left shifter. The piece that acts as the extension by allowing two wires to be plugged into it was simply too much to fit inside the bar with everything else going. Without the dropper post there is plenty of room for the extender, but I concluded it was better to surrender a bit of aero performance so that my descents are faster.

What chastens me in this experience is how this development means that most riders will face an ever-increasing challenge to maintain their bike themselves. I don’t really like this aspect of the bike’s evolution, but my affinity for it won’t change anything, will it?

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