Xiamen Carbon Speed rims/wheels

[TurboKlemi]

I am getting a pair of XMCS wheels and am wondering about T1100 rim usage on gravel. A few times in this thread it is mentioned that T1100 rims are not very suitable for gravel like T800 are. Why is that?
Is it the fear of rock strikes to the side/wall of the rim. Or is it the fear of hitting a pothole or washboard too hard and cracking the rim? Do T1100 rims handle stress worse or do they handle strikes worse?

[toxin]

They replace some material with a smaller amount of a stronger material. Now carbon fibre is an anisotropic material, meaning it has different mechanical properties depending on orientation. So while the wheel still behaves similarly during normal riding, it's less durable against loads it wasn't designed for, like impacts, because now the tensile properties of the fibre make less of a difference and it's more down to the properties of the resin and volume of material.

[TurboKlemi]

Yes, thank you. But what kind of imapcts/loads are we talking about? I see two kinds of impacts:
-Direct impacts to the rim: rock strikes to the side, snakebites, tire deflates and you strike the rim directly against the surface.
-Extra force/load: you drive over washboard and rattles you and the rim like hell, you hit a pothole generating extra force on the rim, you drive over a curb, bunnyhop. Basicaly generating extra load but not directly touching the rim. I am not talking some extreme full force hitting a giant pothole, but rather normal controled every day impact you know

I was at a UCI gravel race in April and people were going 1000 watts over forest paths with big roots on their zipp xplr wheels for example. I imagine that is too much even for xmcs gravel 32mm IW T1100 rims? I ordered 40mm deep 26IW rims.

At least I want to know how fearful should I be about potholes and curbs and washboard. I hope not too much

[toxin]

The biggest difference will be in impacts on the side of the rim.

Now the rest is speculation and you'd have to ask XMCS for a true answer, but the hooks have a non-negotiable amount of volume that needs to be filled. I doubt the material used there changes between layups. Density of Toray fibre is almost identical for all but two grades, so you don't gain anything from changing the material there. The cheapest structurally sufficient material should be fine for every layup level. For vetical loads, the side walls could be built to the same strength across all layups, but I don't know if they are. It's entirely possible the lighter layups get rid of so much material that they are still weaker while using a stronger material.

[muflon11]

I also would be interested which road wheels are also suitable for gravel use. I am planing to use a GP5000 35mm, are there any rims which create a flush areo shape optimized for this tire size?

[Serge_K]

I also would be interested which road wheels are also suitable for gravel use. I am planing to use a GP5000 35mm, are there any rims which create a flush areo shape optimized for this tire size?

As permanent resident of the bro science corner, i'd say a rim that's 38-40mm wide should be optimal (rule of 105, aka bro aero). I have a Conti GP5000 32C on a 34mm wide rim, it measures 34.4mm from memory. Therefore, a 35C Conti GP5000 on a, say, 39mm rim, should measure anywhere between 35 and, idk, 40mm. As such, on paper, assuming your rim is hooked (do not get a hookless rim for that), you should have a rim that's a bit wider than the tyre, following the rule of 105. At the very least, you wont have a mushroom (tyre much wider than rim).
The Silca dude said on a recent YT video that you lose 6-7W @45kmh using a 30mm wide rim with a 35C tyre, vs a 32C. Mushroom effect is real, rule of 105 is the best rule of thumb we have for a good tyre - rim interface.
Last, i think people say that the wider the rim, the deeper it should be, for the wind to play nice. So i'm eyeing 50-60mm rims myself, i wouldnt go shallower than 45.

#Bro science.

[Lotnik]

I also would be interested which road wheels are also suitable for gravel use. I am planing to use a GP5000 35mm, are there any rims which create a flush areo shape optimized for this tire size?

I'm not sure if XMCS has that in offer, I haven't seen any on their site, but there is a rim 30int/36ext available that should be perfect for this tire.

[Da11as]

I'm not sure if XMCS has that in offer, I haven't seen any on their site, but there is a rim 30int/36ext available that should be perfect for this tire.

Well, the name is self explanatory. It is stated as gravel/road wheelset. I bought T1100 rims with steel spokes and it survived pretty bad potholes when I bottomed out at high speeds with ~34 measured width tyres. I won't recommend combining ultralight carbon spokes with ultralight rim, though.

[muflon11]

So for mixed use steel spokes are the way to go right?
@Serge_K: I think you are pretty spot on. So for the 32mm tires do you think the 26 iw rims create a good transition between rim and tire?
For the 30int/36ext it would be nice if Peter could test the real world measurements of a 35mm tires. I think there will be more demand for 35 and 40mm road tires in the future, like the new GP 5000.

[Da11as]

So for mixed use steel spokes are the way to go right?
@Serge_K: I think you are pretty spot on. So for the 32mm tires do you think the 26 iw rims create a good transition between rim and tire?
For the 30int/36ext it would be nice if Peter could test the real world measurements of a 35mm tires. I think there will be more demand for 35 and 40mm road tires in the future, like the new GP 5000.

I think I wrote it several pages ago... My Pirelli RS 30/32 mm tyres on 26/33 rim expands to 33,6/34 mm. The transition is very smooth in front and at the rear it doesnt matter.

[Uberflo]

If you want the smoothest transition ever mount the new Pirelli SL R tyre. No more gap between rim and tyre just one unit

[Takiyaki]

If you want the smoothest transition ever mount the new Pirelli SL R tyre. No more gap between rim and tyre just one unit

How are they to mount though

[Uberflo]

How are they to mount though

Easy, just with you fingers.

[Uberflo]

These are the new SL-R mounted. They significantly reduce the sidewind proneness.

[Fatbonzo]

Is that a 30 or 32? Ordered and not sure, whats better