Tires blowing off Stan's Alpha 340 rims

[tinozee]

Regular clinchers have a kevlar bead that stretches when you mount. Road tubeless tires by hutchinson have a carbon bead that does not. Road tubeless tires stay on.

[PSM]

I'm starting to think it's high inflation pressure in a number of these cases. The above 120psi with a 25mm tire on a 340 rim (effectively more like 27mm) is very high - which negates all the benefits of higher volume tires too.

+1.

Any news here ?

[bikerjulio]

Been running PR3's 23mm tubed at 100 psi for over a year on 1st gen Alphas with no problem so far. Too high pressure might be a factor, along with bead "tightness", and not least - correct seating of the tire. These rims require a lot more attention be paid to making sure the tire is evenly seated.

To the question about "why run clinchers?" I guess it's because I did lots of reading on the pros and cons, and wasn't convinced to make the change- this was 1 1/2 years ago. These rims were discussed and bought as a WW item, and tubeless were heavier than a PR3 with a light tube - say 275g. At the time tubeless were well over 300g plus 25g or so of sealant. The difficulties of a repair on the road was also a factor.

Now that tubeless are getting lighter perhaps I'll reconsider. I'd still like to see more variety and lower prices.

[PSM]

I also use tubes on my 340:s. Because it is still a very light rim. ~90 psi mostly.

[MajorMantra]

Has there been any follow-up on this? Does anyone know if the Alpha 400 has any similar issues? And is this only with road tyres, as opposed to CX?

[kulivontot]

I figure CX tires are safe by virtue of the lower tire pressure...

[MajorMantra]

I imagine so, but it bears verification.

[frohrider]

I use a set of factory built IronCross Wheels on my CX Bike since January '13. I had issues just after purchase with the front tire blowing of twice. A close inspection of the rim bed showed that the factory applied rimtape didnt sit centered on one part of the wheel. Since I applied the yellow tape on my own I never had issues again (with Schwalbe Rocket Ron and Racing Ralph in 33mm).

[MajorMantra]

Interesting to know, as I've just got a good deal on a set of Iron Cross rims.

[bm0p700f]

Quite worrying. So are tubeless set ups not prone to this? It does sound like a pressure/rim heating issue combined with bead stretch from reading this thread. I was think about offering these rims but customers e-mailing saying there tyres have blown off, what kind of death trap have you sold me is not an e-mail I want to get.

[WMW]

Has there been any follow-up on this? Does anyone know if the Alpha 400 has any similar issues? And is this only with road tyres, as opposed to CX?

I'm pretty sure all the Stan's rims behave the same because they all have a similar bead retention design.

The "problem" is that the Stan's rims don't have a bead hook. There is a tiny ridge at the top edge of the rim, but Stan told me that wasn't really doing anything. The tire is kept on by how tight it is. On a normal rim this is *not* the case... even if the tire is loose, lateral pressure against the bead hook keeps it in place. The design of the Stan's rims have some virtues... like making the tire larger and rounder, and the rims are light too... but the tires are not kept on as well as with other rims.

In my case and several others I know of, it was definitely not high pressure. Unless 23mm tires at 90-100 psi is high. In my case the tires were not very tight. Kevlar beads stretch, so even if they are tight going on, they can get loose later.

[uraqt]

I must be getting old, I don't understand how anybody can take the risk using any Stan's rims or the new DA cassette. My Stan's when to recycling and I am waiting for a recall on the DA cassette : )

My safety is worth more than any weight saved or cost!!!

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C

[tinozee]

I feel like a parrot but.. Stan's rims are designed for tubeless tires, and with tubeless tires installed properly they don't blow off.

Standard clinchers use a kevlar bead that is too loose for high pressure on these rims. These rims are designed to be used with the modern carbon bead (hard to mount) tubeless tires.

Maybe we can say that standard kevlar bead clinchers blow off? A chart to show some data on these with different tire setups would be interesting.

[istigatrice]

I feel like a parrot but.. Stan's rims are designed for tubeless tires, and with tubeless tires installed properly they don't blow off.

I think people have commented in this thread that tubless tyres do blow off

[bikerjulio]

I feel like a parrot but.. Stan's rims are designed for tubeless tires, and with tubeless tires installed properly they don't blow off.

Standard clinchers use a kevlar bead that is too loose for high pressure on these rims. These rims are designed to be used with the modern carbon bead (hard to mount) tubeless tires.

Maybe we can say that standard kevlar bead clinchers blow off? A chart to show some data on these with different tire setups would be interesting.

Unfortunately, a wrong parrot. I'm also feeling parroty (although not nailed to my perch), since I have written on this before. See Stan's product description which actively encourages tubed clincher tire use:

Exceedingly smooth, extraordinarily fast and unquestionably the next step forward in performance. The Alpha 340 represents the first implementation of Bead Socket Technology (BST) for the road and cyclocross market. The short sidewalls and wide inside rim cavity allow for lower tire pressure while maintaining a firm tire feel with decreased rolling resistance and a more compliant ride quality. The low weight and semi-aero profile of the Alpha 340 makes for a fast accelerating, stiff and strong wheel built to meet the needs of every rider.

Super-wide 17mm inside cavity
Make clincher tires out perform tubulars
Can be used tubed or tubeless
Recommended for both road & cyclocross use

All Stan's NoTubes ZTR rims require yellow tape for tube or tubeless use. A tubeless valve is necessary for tubeless use. Tape and valve not included with rims. Please see the individual rim description for details.

http://www.notubes.com/Alpha-340-Rims-C68.aspx