Rocky surface? I have a feeling the straighter tyre profile with the w-i-d-e internal leaves the sidewall a lot more exposed/vulnerable.
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This have been a common issue in mountain biking like for ever. If you ride tires with less pronone side knobs and the sidewall balloons outside at the widest point, rocks will hit the sidewall instead of side knobs. My understanding is that tire manufacturers have tried to fix this with reinforced sidewalls, making tires stiffer and less comfortable (and slower rolling resistance on bumpy terrain).
This should be the opposite issue with these wheels. The wheels are so much wider than most others that there is a stretching of the sidewall, not a ballooning out. Sounds like a different issue here.
No. It was a variety of people, probably mostly amateurs.
Seemed surface independent. Some on chunky rock, some on the famed champagne.
I think the smallest tires I’ve seen payson race with these wheels are 2.25s. I wonder if he came to a similar conclusion.
This should be a non-issue with the tires designed specifically for the wheelset, surely? That is, those tires should have relatively wider tread caps and shorter sidewalls so there’s no greater sidewall exposure than a normal rim/tire.
‘Course if folks are using tires from the rather limited “approved” list it’s possible those tires are just relatively flat-prone. This highlights the massive downside to these wheels, in that they really limit tire options.
I was trying to point out that the width of the rim is not the problem. Sidewall cuts like this have been happening with the complete opposite situation where rim width is narrow and tyre width is large, because the sidewall is balloning out.
To me it seems like the tires that was made for these rims haven’t really been tested at all IRL. All that mattered was aero. To make tires for these rims more durable they need wider side knobs, but then they will probably degrade aero.
I think tires designed like this might have higher rolling resistance. I think I remember reading that based on BRR testing or Tom anhalt. Whoever it was believed that a higher sidewall to tread reduced rolling resistance, as hysteresis in the thicker tread is higher. I will watch these with interest, as I’d like to see how it develops, but I am not convinced for tires less than 2.0, and skeptical sub 2.2. Glad I’m not currently in the market for wheels, so I can watch for a bit.
I have to say, I was initially interested in these for the Gravel Bike I’m building, but with all of the puncture issues these are a definite no for me in the short term.
Here’s the other thing, I’ve been running 2.2" Race Kings on 25mm IW rims on my XC MTB for a couple years now - love them (Race Wheels, I do have a set of 30 IW Every Day Wheels too). Granted I’m not the worlds fastest descender or really laying the bike over, but I’m decent and I’ve never felt the need for more width including hammering them down Powerline and Columbine at Leadville and training in east coast chunk at home.
I get the Aero argument, but durability and finishing the race is way, way more important.
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@GPLama how has your experience been? Also do you plan on doing a full review of the wheelset? Sorry if you have already answered this before.
I noticed he ran the trusted ole firecrests too for SBT grvl this weekend.
I didn’t notice that. That’s interesting
Lot of good posts here. I would be reluctant to run the new XPLR on anything less than a 45mm, with thinking they are better suited for 50mm and larger.
I have a bike fitting this week to start a Mosaic GT-1 45 build. I’m going through all the options of the build with the expected scrutiny. I’m obviously very keen on the new XPLR wheels, and if I had 50mm easy clearance front and back, I would gladly pull the trigger. I am thinking I will mostly likely run a 47mm pathfinder pro in front and 42mm in back (unless I can squeeze a 47 in back, too.
I really want the latest and greatest with this build, but there’s too many unknowns about these wheels at this point in terms of performance and the ‘real’ ideal tire sizes.
The Reserve 40/44 are currently at the top of my list. With the 27mm internal width they are a bit wider than many others at 25, but not the jump to the XPLR’s. Of course, the 303 FC’s always have a bit of a ‘sweet’ factor, but not sure I see their advantage over the Reserves.
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Slashy. Well, one sidewall cut last week. Not something I’d experienced with over 15k km on a set of 303 FC.
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Ooof…
Tried to visualise it. So what happens when you hit a rock (for example) with a narrower rim and a bulging tyre, the thread protects the sidewall since the sidewall curves inwards towards the rim edge.
With wider rims, the tyre has a straighter sidewall, so the trajectory when you hit a rock on the very edge of the thread, is that it’ll impact/run along the sidewall.
If you look at @dcrainmaker s video, this is what happened (I suspect). He hit a rock at the edge, and since the impact then continues along the sidewall, instead of “outwards” with a smaller rim, you get a sidewall tear.
This feels like it aligns with @GPLama s issues as well.
Yes, wider is faster, but if you have zero sidewall protection on gravel, is it worth the speed?
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Perfect diagram of what I assume is happening. Being down under the photo was already upside down and makes a lot more sense. 
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I was obviously assuming that it would be correct orientation for you guys down under 
Haha!
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I think with less stretch, more bulge on a narrower rim, there’s also more compliance and “give” in the tire which should help as well.
Zipp’s graphics is very different from yours. Looks like there is more of a bulge even on the 32mm internal rims. From the images I’ve seen the side wall cuts have been where your arrow is pointing, not on the exposed/protected area.
I suspect the problem occurs when the rim is leaned on the side and the sidewalls become exposed.
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