This is one of those areas where the bike industry adopts the “more is better” product development approach without working through potential combinations. There is also a lack of communication / corroboration between rims manufacturers and tire manufacturers, IMO.
The trend is obviously towards wider rims / wheels, both internally and externally…so if 25mm ID is good, then 27mm is “better”. So then 29mm has to be even better still!!
The end result is that there is a LOT of grey area…it sounds like this particular rim / tire combo is in that area. The fact that RH has contradictory information on its own website further supports this idea.
Personally, I would not try and use that combo again…even if you successfully got them to mount and stay, could you ever really trust them on a descent / corner? It would always be in the back of my mind…
Hopefully the ERTRO standards help sort this out moving forward and there is a clearer line between combinations.
I still personally it all comes down to initial installation. Every tire is different. Not bad or better, or safe/unsafe rim combinations…but every setup has to be treated as it’s own thing…ensure the fit is good, adjust if it’s not. I just assume all rim/tire combos are going to be too loose to start until proven otherwise.
My personal rules of thumb…
Should seat with a floor pump
Should hold air for a while (minutes) with no sealant.
Should still mostly hold air if you push a bead into the center channel when at low pressure.
If any of those don’t happen, I add rim tape to make a tighter fit.
As I learn more about this stuff and look at all the things I have.
I think hookless is the real issue here since the standards are so everywhere.
This rim combination I have is the most radical of all my stuff, its also the only hookless setup I have currently (I was about to pull the trigger on some Enve 6.7 but am thinking against it now).
I didn’t want these NXT45AGX rims for wide tires, I wanted this combination because in the back of my little head it got me so close to the 105% rule for racing with the 35mm. If that holds true for wheels this big or not I have no idea but that’s where my mind was when going with them.
you‘d need 3x(or 2x?) the height of the tyre for an aerofoil shape so assuming the tyre is 38mm in height three times that is almost a 12cm deep rim. That’s not practical on a gravelsetup imho.
There are other low hanging fruits that are much more attainable and safe to pick. Aero helmet, skinsuit, shoe covers, aero socks. Choose a save tyre to ride and don’t fixate on the 20% of the system being aero but on the other 80%.
Sram has been granted a patent where they want to glue a bead back into a hookless rim. They claim in that patent that manufacturing costs could be reduced with hookless rims and want to now glue in a bead. What a clown world we live in. Hookless is just a cost cutting measure in manufacturing and I‘ve yet to see a benefit other than higher margins for the seller. I don’t buy the „less pinchflats“ reason.
While I don’t know the manufacturing costs, based on my previous experience, I highly doubt moving to hookless is causing a significant shift in margin. Especially at these prices…it takes a BIG shift in COG to see a substantial move in margin.
That said, if they are able to significantly reduce their scrap rate by moving to hookless, that could cause a reasonable improvement to their bottom line.
I don’t know them either. I’m just regurgitating china cycling and the likes „in the know“ youtubers. If there was an actual measurable benefit we would know about it, I think. Many of the cycling industry’s claims are really opaque and hard to quantify for the average consumer. How should the average cyclist know their rims G height or BSD when the manufacturers themselves often don‘t publish them.
Before purchasing RH tyres for 80-100$ a pop I‘d like to know beforehand if they work on my rims. I wouldn’t want to find out like @teddygram did
Working at a industrial manufacture and a small set machine cost you would be surprised at the cost.
To add a hook to a rim, they have to spend more on carbon wall thickness to begin with and then when the product is finished they will machine the crotchet into the wheelset. This also leaves room for user/machine error to occur after the mold process is finished.
If you look at large to scale manufacture, lets say it cost $10 more per wheel to do this with labor, machine cost/upkeep and scrap cost; I could maybe see a potential of $10 per wheel, maybe more. However if you look at the lifecycle of a wheel profile which I would guess is 50,000 rims (25,000 wheelsets) but $10 x 50,000 wheels is $500k that they could just save because of a change in standards, ideals marketing etc etc.
This math works out to 8,333 wheelsets a year for 3-years… I bet specialized does that or more, but their high end road wheels are still hooked. I dont know what their wheel product cycle is, I imagine its 3 years but could be longer.
More complex manufacturing = more cost. It’s probably more costly in tooling, material, more labour, more out of spec rims that you toss and so on. If there was a tangible and measurable benefit we‘d probably know about it. Right now it’s just „trust me bro“. Same with wider wheels.
I firmly believe a lot of these numbers and their variation from company to company is mostly a product of their particular attorneys level of squeemishness than any real world engineering differences…
Just to be clear…I am not defending the idea of hookless rims. And as I noted, reducing scrap cost could lead to a significant improvement on the bottom line.
But that isn’t what “margin” is typically defined by…at least gross margin (and that is what is typically referenced in these scenarios…gross profit dollars / revenue dollars)
But we are getting way off track here…my point was simply that the idea of margin is not likely driving the change to hookless, but reduced scrap rates, higher efficiency, etc. could be a significant factor.