A couple rides in and i have a good bearing on the supersix evo and how it differs to the madone.
Firstly though, the build was purposely specced in a way to be different to the madone. This probably heightened the differences i experienced.
Initially the supersix evo felt smoother than the madone. Even though the madone has the isospeed, i kinda realised that it isolates and mutes the impact coming through your saddle (which makes sense since it is a seattube thing) but the feel of going through say a pot hole or rough surfaces still resonates and transfers through your pedals. Isospeed doesnt really do much for your feet. It also seems to work better on bigger and slower impacts when muting saddle feel. Front end wise on the madone i would say that the feel matches what you feel through the feet but not what you feel through your butt. The supersix in this regard is smoother by a fair margin. It feels similar in-terms of saddle feel but your hands/arms/feet are a fair bit isolated. Now the biggest thing to note is the tyre/pressure remains the same on both bikes (gp4000s II) but the wheels are very different. Shallow vs 404 NSW. I am sure that does something. Also, the bars on my madone arent wrapped on the tops as per most aero bars and i am sure that transmits more bumps as well (although i would say that with feel from the hoods it is still a fair bit harder). This smoothness gives you a sense of gliding along when riding the supersix. It also gives the ability to put power down over rough surfaces better.
First ride in and i had every intention in keeping it sedate but a descent came up and before i knew it i was not taking it sedate. Sure, i wasn't purposely trying to go as fast as possible but it was a "spirited" pace. It was enjoyable to descend for sure. No deflection from crosswind made it quite stable. The smoothness mentioned above helps too over the roughish descent and then the alloy wheels gave a lot of confidence in braking. All up it meant that i got a PR on that descent over many past attempts. It also told me that the geo was fine. It is cliched but it was immediately comfortable.
After the descent came the ascent. Went slow at the start because it is a social ride and we started taking some pictures but about 1/3 way in i decided to see what the bike was like climbing. It was good. Got a PR on the ascent as well and i would say it was a 8/10 effort. It feels slightly more rewarding to climb on this bike. The madone certainly could climb but it didnt feel as rewarding. Felt like a diesel engine up the climbs. The supersix felt very sprightly and ultimately i felt like what i put in was going somewhere worthwhile and that pushes me to go a little harder. I think the shallow wheels also would contribute here. They are about 100g at least in rim weight so that should account for something.
Previously commuting into rides and back from rides i wouldn't really look forward to hills. I find them slightly annoying. Now my attitude has changed and i am actively enjoying up's slightly more. Given that i am 5'7 and 52kg's, i guess the bike suits my physique a little more.
Next test, a faster flat ride. Definitely harder to hold top end speed. Sitting in a bunch you don't notice it much but if you are off the front and trying to sustain 40-50km/hr speeds, the supersix suffers in this regard. I am sure the wheels play into this significantly as well but looking back at power data (i have power meter on both bikes and have done this route on the madone a lot), i can see that on average, on the madone i would be sitting at roughly 10-15% and even 20% less power vs similar speed on supersix.
Last thing, as mentioned previously, i purposely changed up the geo for this bike. the reach is about 20-30mm less than the madone and the stack is pretty much similar. What i feel is i am definitely less stretched. However, it seems easier to tuck myself when i really want to be aero ie when i am trying to sustain 40-50km/hr. I am changing the stem to a -17 120mm soon to see how that feels as well. Good thing with this bike is i am allowed to experiment with positioning slightly more.
Overall pretty happy with the bike. The brief was to build something different and i think i have succeeded.