Oh yeah….this was 2009ish. Cable everything….each HB setup had full length cables and matching housing as noted for the front. I would unloosen all 4 cable fixing bolts (2 brake, 2 der), loosen all the stem attachment bolts and just remove pull everything thing though.
Place the new stem / HB in place, run the cables through all the housing left in place and tighten everything back up.
Would be a total nightmare with hydraulics and fully integrated HB systems…if not simply impossible.
FTFY 
Thanks ! Very interesting (just read the transcript for now).
As has been mentioned, go play with best bike splits and tinker with adjusting CDA. Figure a road bike is somewhere around .35 to .4 a crappy TT position gets you to the high .2s
I back calculated my cda after a 40k tt on a road bike to .35 (299 np 296 ap for a 1 hr 40k).
In the below calculator, I used my calculated cda on a road bike vs a .25 cda on a TT. If I road an IF of .7 for a full distance ironman leg I would finish the ride in 5:20:13, to do the same time split on a TT bike i would only need to do 165 watts. That would make a massive difference when I have to run a full marathon after the bike.
In my mind, don’t look at it as how much faster the TT bike is, but how much fresher you can be to go run a marathon.
I’ve discussed my approach on some other threads but for what it’s worth, after a lot of experience, I can share some pretty concrete data:
I got pretty far using Redshift’s aero setup on a 2013 entry level carbon road bike. Seconds to take on an off using Redshift’s novel quick release connector and adjustable seat. I had Di2 as well, so I inserted a junction B under my stem between hoods and could connect for aerobar end shifting as well. This added another 10 seconds to the road/TT swap. As I got into it more, I started moving to longer, and more negative stems - which got progressively faster. With 65 mm wheels, no bottles/cages on frame, BTA hydration, tight 2-piece jersey/bibs, GP5000TL 25mm, and a TT helmet - My best result with this road setup was 58:56 for a 40k flat TT at 260W. I was still riding this as a road bike regularly, and probably had better core fitness to handle the long/low stem.
I then got a “real” 2016 TT bike (P3) - the day I got it, and replicated my position I had pushed to on the road bike, I saw no obvious gain in speed on usual loops - within 0.2 mph either way. Then, I swapped in a TriRig front end that both let me go even longer/lower, and more importantly, allowed lots of easy tuning to do field testing to make subtle tweaks working on improving CdA. I also got a skinsuit, and cover for the same rear 65 mm wheel. With all of this… My best result with this TT setup was 56:58 for a 40k flat TT at 268W. Not the same course, but both courses were loop/out&back with no net wind bias, similar temperatures, maybe a tad more traffic drag assistance on the course with the TT bike.
Net - a 0.9 mph advantage for total combination of a TT bike + 8W + rear disc cover + skin suit + further position tuning over a pretty well-optimized 10 year old non-aero road bike with clip-ons.
How much of that do you think was really attributable to the TT bike frame itself? 
And I’m sure I could adapt my road bike even more closely to what I’ve learned as an optimal TT position. Similarly, at our weekly local 10 mile TT series or strava segments - continued incremental gains, but nothing like the huge gains the first time I hit some of these with my dialed-in road bike/aerobar combo vs. prior PRs.
All that being said, I do really like my TT bike and I still have more opportunity to keep pushing the position on it while also returning my road bike to a more conventional position now, so I don’t regret it at all. But unless money is no object, I highly highly recommend the redshift kit and a couple inexpensive UNO stems off e-Bay as a gateway to see if you like TT’ing first.
Sorry. It was late and after a long work day. Sometimes I confuse myself 
but, really I was just trying to say (through the article and youtube) that TT/tri bike is the fastest but, also more efficient. A road bike (or gravel bike) with aero bars is going to be fast but, not as efficient. It’s related to seat tube angle. But, yeah, the efficiency is what I was trying to highlight.
Hi @PawelKozela , I am only looking at the same question a few months later than you and found this. In the end, I believe you may have already your TT bike. Good news is that this also supports it.
I am having the same conclusion.
Yep, I bought a Canyon Speedmax.
I love it and it’s definitely faster than my old Canyon Endurace - but the spec level is also not comparable at all, so I don’t know how much of that is thanks to the geometry of the bike, and how much is thanks to wheels, tyres etc.
Even going from an endurance road bike to an aero road bike, I am fairly certain that the most significant difference in speed is due to body position. The next factor should be clothing (tight fitting clothing is faster than loose clothing by a significant margin, a one-piece body suit is faster still). I reckon wheels are next.