That was close.

[Racing roadkill]

I was riding about and testing the replacement rear mech I had to fit, because someone rode into the back of my bike, a couple of weeks ago, and wrecked a brand new R7000 mech that had only been on for a couple of hundred miles ( but that’s another story ). Anyway, I noticed that my front tyre ( tubeless ) felt like it had something stuck to it, so I stopped and checked the tread. It felt a little odd, as I rotated it and checked the rotating tyre with my hand, but I couldn’t see anything obvious, so I rode home ( about another 10 miles. I checked it properly when I got home.

The little silver bit just above the spoke nipple is part of the design of the rim ( Mavic Ksyrium ) the issue is the bead / side wall tear above it. Yet again, a bloody side wall has failed on a tubeless tyre. They are massively useless. I checked that the pads were clear of the tyre, and they are, and that there was no debris causing contact, there wasn’t. That really is it for tubeless road tyres for me. Utterly useless , and more expensive than clinchers. That’s 4 side wall failures, on tubeless tyres, in as many weeks, on 2 different bikes.

 

[I like Skol]

Name and shame, what tyres are these (brand & model)? Maybe you should be posting this in the other current tubeless debate thread?

 

[I like Skol]

I just had another look at this as I can't understand why your tyres would fail this way simply because they are tubeless. I know you said you checked the brakes weren't rubbing the tyre, but looking at your picture it looks like the rim braking surface is being contacted up to, and maybe beyond, the outer edge while there is lots of clean untouched metal closer to the spoke bed. I would say IMO your brake blocks could do with lowering a good few millimetres to make sure they are not touching the tyre when under full braking force. You have plenty of unswept braking surface available to do this.

 

[Racing roadkill]

I just had another look at this as I can't understand why your tyres would fail this way simply because they are tubeless. I know you said you checked the brakes weren't rubbing the tyre, but looking at your picture it looks like the rim braking surface is being contacted up to, and maybe beyond, the outer edge while there is lots of clean untouched metal closer to the spoke bed. I would say IMO your brake blocks could do with lowering a good few millimetres to make sure they are not touching the tyre when under full braking force. You have plenty of unswept braking surface available to do this.

Yeah, that’s definitely not the problem. I lowered them as far as they’d go, and to begin with, it wasn’t enough. So I got the dremel out, and milled the callipers right down. The top of the brake blocks ( which have a taper on them )are a good 2mm clear of the tyre now, on both sides. The side walls are total gash on the tubeless tyres because in order to not make the ride and handling horrendous, they have to be very ‘flexible’. The damage has been done by catching the sides of pot holes, and ( shock horror) small stones. The failures haven’t just happened on this bike, or this wheel. The braking track does look like it’s got more to use on this wheel at the bottom, but that’s purely the design of this particular wheel. There is no more material that can be milled out of those callipers, there doesn’t need to be either. I could go with long drop callipers, but they don’t do an R7000 long drop.

 

[gbb]

Doesnt initially look like brake damage to me. If it were, it'd extend all the way round the rim but yours doesnt appear to, the 'deformation or damage' looks localised. As the 'bead' or moulding line disappears out of the photo on the left, it appears to look a more normal distance from the rim.
I dont know anything about tubeless but I'd say that was either coming away from the rim or he very fabric of the tyre is letting go, in essence, defective.

 

[Milkfloat]

Could something or someone have 'sliced' that? Can you provide a photo of an unaffected part of the tyre/rim?

 

[si_c]

Doesn't look like pot-hole damage to me - it appears more that the sidewall is tearing away from the bead vertically - hence a manufacturing defect. You've said you had 4 tubeless failures in the last month - what brand/model of tyre, all the same? Same mode of failure?

 

[Globalti]

Mystifying.

By the way it looks from the photo as if somebody has tried to true that wheel, twisted the spoke nipple and left the spoke twisted, which would be putting it under unnecessary stress. See if you can straighten the spoke; it should rotate inside the nipple. The stresses in those Mavic spokes are immense; if one breaks it lets go with a frighteningly loud bang and the wheel goes straight out of true.

 

[CXRAndy]

They aren't Schwalbe Pro Ones

 

[Nigelnightmare]

What pressure are you running?
I've had that sort of damage to a tyre after a long steep hill combined with hard braking, my LBS said it was probably due to overheating (must admit the brakes were smoking a bit)