And more importantly, how to stop it happening again:

Allow me to set the scene: FoD on Sunday, on the final descent (after coming out of the trees), there is a fast drop with a rather harsh transition on a right hand bend- during the corner, my rear wheel spectacularly lets go at about 25MPH, loses grip and tries to come around to meet me face to face! I hear a god awful screeching sound (like metal on metal), and then manage to somehow through luck, rather than skill recover the slide.
Upon inspection at the bottom of the run, there was Stan’s fluid everywhere along the bead of the tire (along with some of my own no doubt), but other than that, everything looked normal?

I assume the tire tried to escape off the rim, but what would cause this?
I was running about 30psi, the tire is a 2.25 nobby nic and the rim is a stans crest.

I would very much like this not to happen again!

Your thoughts?

Dry sealant? happened to me on the front.

Had you lost air pressure?

Much loss of tyre pressure? The screeching sound may have been your own fear expressed vocally… 🙂

Sounds like the tyre burped. Just stop being so rad and cornering so hard. Not sure about the metal screeching sound though.

There has been talk of a spate of schwalbe/stans weirdness. Is it a TL version?

Using a rather scientific method to measure if there was any air pressure lost (i.e. pressing my thumb in to the tread), I can deduce no air pressure was lost… maybe… well… not much – perhaps?! 😀

New sealant had been added the day before to both tires.

I was thinking maybe the screeching was rim/rock interface!

Rim against rock for the screech?

Too slow, you thought it yourself.

We did the run 3 times in total, the first time was absolutely fine… the second time the “incident” happened, and the third time I took it much much slower but you could tell it wanted to do the same.

Don’t downhill on Stans Crest and tubeless setups? You just found the limits of your bike setup. Congratulations.

I’d suggest you get some wider rims if your doing drops and corners at 25 mph.

I did something similar recently, not a severe, 2.2 Rubber Queens on Flows – check 6 mins in this:
http://www.youtube.com/watch?v=da3f4dGGQmw

Tyre folded and burped on landing, big washout, then resealed after spewing some sealant. Pumped it up and carried on riding. I think that was due to a slow leak leading to pressure drop (Rubber Queen sidewalls very porous – front holds pressure perfectly, back full of tiny pinholes and goes down slowly).

Low pressures and high side loads lead to the tyre peeling off the bead, either momentarily or permanently! Solution is a combination of higher pressure, wider rims or tighter fitting tyres (try rim strips or more wraps of tape).

Bwaarp, it was the Verderers trail – there isn’t anything on it that should challenge a crest rim! It’s all very rollable.

*edit* and it certainly couldn’t be classed as “downhill”.

hmm worrying.. i recently got a Crest and noticed the bead lips are much smaller than on the Flow.. thought it might not hold the tyre while i inflated.. is this a common problem with Crest then?

Did you run out of talent?

crikey – Member

Did you run out of talent?

That would suggest I had some to begin with 😛

Gravity-Slave: I was thinking higher pressure, but it would be at the expense of grip. Nobby Nics are quite sensitive at (read: rubbish) higher pressures.

I may well try more rim tape though?

@4:57 was the point it let go (not my vid by the way!)

maybe the screech was the magnet of your speedo causing some rubbing? I suggest that you may be even faster if you stop looking at the speedo!

Had you splashed on too much Eau-de-Gnar…

Not sure if this helps, but I do Verderers quite regularly on Crests and NN but not tubeless. I’ve never had a problem with the rear tyre, it’s the front washing out I have trouble with.

Burpage/Rolling tyre caused by narrow rim/wide tyre @ low pressure.I need to put a flow/p35 on the back of the yelli to stop mine being lairy (or stop cuttying a 29er).