Except if your 25 mm tire can’t reach the optimal pressure without flats or rim damage. Then you have to have wider tires or you are sacrificing speed. He says so many times on that blog and his videos.
Also, don’t forget that wider tires mean you are beat up less, so you fatigue less (not eating as much energy to control the bike, less friction going into your muscles) and are faster (able to put out more watts) later in the ride.
Most current MY2020 and coming MY2021 bikes that come on 28’s are going to be pretty comfortable. Position, tire size/pressure, and seat post type/length are what I would consider the biggest things that change comfort. My recommendation: Get a fit and then find the bike that has the geometry that fits you best. BMC, Scott, Spec, Canyon, Trek, etc. (I have an Addict RC on 28’s tubeless and its fantastic.)
Actually comfort (from reducing shocks transferred to the body, not fit) does equal speed. It’s simple physics. Any shock (acceleration) transferred into your body is wasted energy. It takes a lot of energy for the bump to move your body upwards and backwards. That wasted energy could instead have been used to make you go faster or use less energy to go the same speed.
Here’s a great article that proves this with data and combines it with other data (including Josh’s).
This is why most performance bikes are moving to wider tires. As long as your wheels are aero optimized for your wider tires, wider (up to a limit) is faster. How wide is optimal? That’s hard to say, and definitely depends on the road surfaces. However, almost all the major players now agree that 25 mm are not wide enough. 30 mm actual width (28c on i25 rims) seems to be the sweet spot for road use based on what ENVE, Zipp, Specialized, etc are putting out there.
In the same boat. My “race” bike is a Tarmac that only fits in 26mm tires (maybe I can fit in a 28, but my rims are too narrow for that). I don’t “race” anymore. So I could go Diverge, but that’s probably too far in the endurance direction and would leave me wanting more when i do road rides. New SL7 is interesting, but I think I’d like a little more towards gravel.
The outgoing Ritchey Outback looks interesting, but I’m sure would feel like a boat if always riding road.
Domane is very interesting. Are they threaded bb’s again yet though?
yes. I’m looking to test ride the Domane and Madone, not sure which direction to go until getting some time on both bikes (I have a 2015 first-gen Domane).
Suspension losses are exactly why I started casting my eye on a new bike. I have a Colnago C59 which is a fantastic bike. It has a mid 2000s geometric paint job that I was thinking that I’d upgrade some day and make it my dream paint job.
Then I moved to southern NM where the roads were often rough farm roads. My 100psi 25mm tires were feeling brutal. I lowered it down to 80/85 but I was riding the edge of what would work for me with those wheels. My friends were riding Madones and Domanes with ISO speed and 28mm tires. They knew what was up.
I got a new wheelset and went tubeless (25mm GP5000TL) and 75/80 psi was now possible. This was about the best I could achieve on my C59 with it’s mid-2000s clearance designed for 23mm tires. It was okay but not nirvanna.
I think my next new “magic bike” is an SL6 or SL7 with 28mm GP5000s (probably 30mm actual) or maybe even the 32mm GP5000TL on the SL7. The Colnago C64 is also a strong contender but it will only take up to 28mm tires (30mm actual).
My non-tubeless GP5000 28c on 25 mm internal rims measured 30.7 and 31 mm (front and rear) at 65 psi.
The difference in volume between 25 and 28 mm actual width is 30%
curious what people here think of the 2021 TCR lineup (i am specifically looking at this one here https://www.giant-bicycles.com/us/tcr-advanced-1plus-disc-pro-compact-2021). I do mostly fast road riding but want the comfort of faster tires and the ability to go off road occasionally, so want something with more of a race geometry but 28 - 30mm tires (this has clearance for 32mm according to Giant).
The Parlee R27 is an awesome bike.
Aero, relatively light and incredibly comfortable.
Not a huge brand but worth a look.
Yeah, looks really stunning! 
So yes, I probably found a perfect bike for me…I only have to figure out how to get the R27 for the price of a Canyon Ultimate 
That’s true but your statement false apart when i ride on my Venge with my slower friends with little pressure on the pedals.
All kind of sore spots tend to pop up i never experience when riding by myself 
Your problem isn’t your Venge, it’s having slow friends! Either need to upgrade your friends or use this as an excuse to buy another bike optimised for slower riding…
Oh man I hate you! After your quote I just can´t stop looking at it and I am affraid I fell in love with that beast 
but it´s waaaay over my budget 
Okey, I did not try to negociate some kind of offer, but as there is only one importer in my country and this guy is… let´s say special… I don´t have much illusion
Besides, I just can´t find any independent aero testing of RZ7, claims of Parlee are nice, but I really would like a direct comparison to the likes of Aeroad, Madone, Tarmac… otherwise it´s just guessing. It certainly looks aero, but hey, Madone looks like crazy fast bike and in fact it´s not so stellar in the Tour Magazine protocol… 
N=1 but my Foil is relatively fast for a small dude like me and supremely comfy. Manages to be reasonably stiff in sprints (mind you I’m 5’8 and 68kg) and still rideable all day on any terrain. As others have said though, the fit is what makes most of the difference, the bike somehow allows me to maintain an aggressive yet comfortable position.
Soooo guys, I think I just can confirm my previous opinion. One friend of mine wanted to sell his SuperSix Evo Hi-Mod 2020. Yes, the one that recieves glorious reviews everywhere as a great racing machine which is supremely comfortable.
He runs exactly the same rims as I do (LB AR45, 21mm internal, 28mm external width), same spokes (Sapim CX Rays 24x), same lacing, only different hubs (Extralite and me DT350), same GP5000 at 25mm, same pressure (5,5), very similar saddle and quasi same posture setting… I came on my current beloved bike - titanium frame with carbon rear and went for a short test ride around the area
And boy what a difference! Okey, I have to say that the acceleration is simply STELLAR. It is mind blowing how easily this machines goes from a stand still to 30km/h… really great. BUT I suddenly felt each and every crack in the tarmac, it was also “louder” - all those imperfections (and I mean imperfections, it was really far away from a bad surface) found the way not only to my body, but I also could hear them.
Switch to my bike and… whoooush, like a cadillac. Okey, it does not get up to speed so easily, but suddenly the world was sooooo much smoother, quiter, just… right 
Yeah, I fell again in love with my old bike and understood that SuperSix is not a dream bike for me…
Now my big question is - how it comes that you read from the test how comfy this bike is? Are those journalists so much on a pure super stiff bikes that they really call this “comfort”? I thought that those super harsh super stiff carbon bikes have been the thing of 90´s before producers understood how to make a good frame for everybody and not just a Pro sprinter… besides my old carbon Dedacciai was also nicely compliant… so… I just don´t get it honestly
I’m sure it depends a lot on what you’re used to riding on. I do 95% of my riding on my BMC Teammachine and it’s not stellar when it comes to smoothing out bumps and such, but because I’ve been on it that much I’ve just become acustomed to it. Obviously, there are always the occasional bigger bump or what not that jar you a smidge but in general I’m very dialed on what the ride should and will feel like.
I imagine it’s somewhat similar for those reviewing bikes, where they have ridden so many of the top-end carbon rides that the fit and ride is fairly status quo. The other assumption is that most will ride one of those bikes knowing that they won’t smooth out the rode as much as some others but they make up for it with the other aspects such as quicker up to speed, etc.
I have a madone with the more “relaxed” geometry that they used to make several years ago and as much as I want to believe I’ll find some huge speed gain with a more race-y frame, logically I have to believe it’s very minor, as you illustrated. And likely, the real speed gains (or lack thereof, will be in my legs). Good post!
according to this: Why It's Impossible For Steel Frames To Be More Comfortable Than Aluminium - YouTube your hunch about the seat post is spot on. Exposed seat post, seat post design, and to a lesser degree seat post material seem to be the biggest source of suspension on a road bike. combine that with some 28s, latex tubes or tubeless tires, and you’ll be quite comfortable as long as you fit on your bike
@csyversen Thank you for the video link. It confirmed that I had been focusing on the right things, though I will say I didn’t think the frame was that inconsequential to comfort. It also is pushing me to try a carbon handlebar.