The Di2 brake/shifters route the cable inside the bars and the wiring outside the bar. It is hard to keep up with 3T bar permutations. Are the bottom side holes you mention, located at the bottom of the bullhorns with another set of holes along the back of the bar near the stem? Or are you saying you have a version of the Aura Pros with the cables exiting the bottom of the bar near the stem? A typical Di2 install would have the cables run internally from brakes to back of bar exit with Di2 wires entering bar through bullhorn holes then exiting bars with cables, near stem. There are some photos of 1st gen Di2 installed on p5-3 with Aura Pro here:http://raceyourself.ph/tag/3t/

I have a P3 with those bars and both the Di2 wiring and brake cables come out of the single exit point. I'll try and get some pics.

my bars are only 2 yr old but have only a single exit hole on underside for brake cables. The bullhorns have an underside hole the e-wire could enter but no "extra" hole for them to exit.

may have to route Di2 wires from bullhorns on the outside. fugly.... but functional, I guess.

enlarging or drilling a new hole for e-wire probly not a great idea.

yeah- the bars on those P5's are definitely "different". Same model base bar (3T Aura Pro) but they have an "extra" set of holes on the trailing edge of each side near the midline where the Di2 cables exit. Not the same as what I have (bummer).

I guess that means external routing of e-wires and lots of electrical tape.

It sounds like you have the version without the more aero back edge cable exits. I would just drill the bars where you want to route the Di2 wires. One small hole on the bullhorn bottom. Then enlarge the cable exit holes to allow Di2 wires to pass out with the cables.

If you can't bring yourself to modify the bars then I'd suggest using the Shimano Di2 "wire cover" material as it does a pretty decent job on external wiring: Wire Cover Kit.

well, gonna be doing some drilling/dremeling the (2013) P2 to modify it for internal routing so might as well go all the way and drill the basebar, too. What's the worst that can happen? (please don't answer that)

I have some of the Shimano tape you referenced that I used on my externally-routed Di2 road bike. Works great and doesn't look too bad. Not a great option for a P2, though, due to shape of downtube.

I just wondered how you got on with the drilling? I have a similar problem.

SO- I drilled the bottom of the 3t bars only to realize that there was no cut-out on the bullhorns which would have allowed me to route the external Di2 cable back into the bar to then exit the holes I drilled under the bars near the headtube. Doh!!

While there is a lot of material near the center. bottom of the bars, I was NOT willing to drill the bullhorn extensions just behind the brake levels for fear of weakening that area too much. (I forgot that it was my OLDER, carbon aero bars that had that extra cut-out in the bar extensions to internally route a cable)

So, there was no way to get the Di2 cables INTO the bars for them to exit out of these nice, new holes. Oh well.


However, my internal routing and internal battery on my Cervelo P2 went spectacularly. I placed the battery inside the seat tube and all cables are routed internally. Required a bit of drilling at top of downtube (where shifter wire originally entered), a bit of drilling at the bottom bracket area, and a bit where the Di2 cable exits the seat tube for the FD. All very minor stuff and it has held up w/o problem for many miles.

Good luck. I can't even begin to say how much I love Di2 on a tri bike. Much more than I thought I would. I have had it on my road bike since just after it was first released.