I made the point that wider tires work just fine. It is a fact, they do. I even said that you could find “better”. That exact word is in my post.
To reference my initial examples SBT was won using 44s mounted onto a 19.5 ID wheel. I think it worked as intended. I have personal experience that 28s on 21 ID will win the weeknight crit. If he thinks the Shimano wheels are nice, he should buy them. By all accounts, they are a great wheel. And I’m just going to leave it at that. I genuinely have no interest in debating this, given I already conceded the point you keep making in my very first post.
Going from anecdata here, the most popular Shimano wheelset is actually a cheaper rim brake training wheelset some racers use here: it is seemingly reliable, inexpensive and works well. (For reference, I live in Shimano country aka Japan.)
But even here in Shimano country (= I live in Japan) I haven’t seen Shimano wheels out there. Someone on a local cycling forum tried to sell DuraAce rim brake wheelset for very little. It didn’t sell.
It is primarily for aero gains. If the tire is too wide, the wind flow separates from the rim and it won’t flow around the rim as designed. This is definitely not marketing and based on sound physics. However, when quantifying aero gains, this is when marketing sets in.
I think you are mentioning a very important point: a lot of discussions about wheels are reduced to depth, aero gains and, to a lesser extent, things like inner rim width. Ride quality is difficult or impossible to quantify. Ditto for cross wind stability (which is generally great these days, it seems to be a solved problem at least until depths of 45–50 mm). In terms of ride quality, my favorite pair of wheels are 3T’s older 35 mm deep wheels: very supple, good feedback from the road without being harsh and I was cornering as if I was on rails. Granted, I haven’t ridden too many carbon wheels. My deeper Discus 45s are also great in this respect. On paper, they don’t look super great, though. E. g. they are not light. They aren’t heavy either, just nothing special in the spec department — apart from being designed around wider tires. But they ride great and are exactly as stable as my previous shallow aluminum wheels. IMHO that is probably the biggest advantage of carbon wheels, a potentially much better ride.
While I am non-plussed about Shimano wheels, I have nothing but great things to say about Shimano hubs. (Feel free to search the forums or look at the first post in this thread, I’m a big fan.) You ask about maintenance? I have never ever maintained any of my Shimano hubs (all MTB hubs, but I reckon they see much more abuse than road hubs). All of them outlived the bikes. Again, zero maintenance, spanning more than two-and-a-half decades. Theoretically, cup and cone bearings should be worse, but for some reason Shimano makes them work.
The worst thing I can say about my XTR M9100 hubs is that they are incompatible with 12-speed cassettes that start with a 10-tooth cog (I know I could use a 11-50 12-speed cassette, but that’s not what I have in mind). Third-party hub vendors are (and have to be) more flexible here in terms of support for different standards.
AFAIK this depends very much on your rim/tire combo: I have Stans NoTubes Arch Mark 3 rims and Specialized S-Works XC tires. Putting on the tires required less effort than changing tires with inner tubes. I used tire levers as usual, but was struggling less to keep the tire on. I used a regular track pump to inflate them after putting soapy water on the edge of the tire.
But I know there are combinations of tires and rims that don’t want to play ball. Overall, it is clear that the future is tubeless. A lot of (most?) pros in the TdF went tubeless, many of them with tire inserts. Having rims that are made for tubeless tires, especially when you pay that much, seems like a good idea.
I think engineers do worry about that, which is why on most aero wheels the inner rim width is 23–25 mm these days: they tend to be optimized for 28 mm tires. 3T sells deep wheels that are optimized for gravel tires (their Discus 45|40 have an internal rim width of 29 mm). Also have a listen to Hambini’s analysis of aero wheelsets. I think it is
We are arguing in circles: when I spend €2k/$2k on a set of wheels, I don’t want them to work fine, I want them to work great. Yes, you can put on 40 mm tires on narrow rims and ride. But it does have a significant impact on your ride, because the tire shape is different from what the tire manufacturer intended and you need to ride higher pressures because the shallower inner rim puts less tension on the casing. Again, if we talk about a wheelset you already own (Can I put 40 mm wide tires on my wheelset?), sure, why not. But I don’t think it is worth spending that kind of money on wheels that are at the very least nothing special yet expensive, at worst behind the competition.
The trend for road tires goes to ever wider tires. My 3T Strada was one of the first (aero) road bike frame sets designed around wide tires, and now most road bikes take at least 32 mm tires. (My 28 mm tires surely measure about 30 mm.) But nowadays many people ride wider tires than that. Manufacturers continue to put out 30 and 32 mm wide versions of their road tires, and people love them because they are more comfortable and give you more grip. Shimano is being Shimano (i. e. super conservative and behind the trends) by ignoring this.
Shimano hubs can go forever. I have a set of Shimano XT hubs in one of my old MTB that I just keep around and still ride because I just love this bike from forever ago. My first big purchase as a teen back in 1992. The hubs still roll smooth while I am replacing bearings in a set of DT hubs after one season of cyclocross
They are a total mystery to me: technologically they should be inferior, but they just keep on working. Like I wrote earlier, I have never done any maintenance on Shimano hubs in over 25 years, and they always lasted for as long as I owned the bikes.