Tires blowing off Stan's Alpha 340 rims

Discuss light weight issues concerning road bikes & parts.
tinozee
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by 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.

by Weenie


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PSM
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by PSM

mises wrote: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 ?

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bikerjulio
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by 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.
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PSM
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by PSM

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

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MajorMantra
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by 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
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by kulivontot

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

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MajorMantra
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by MajorMantra

I imagine so, but it bears verification. :)

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Juanmoretime
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by Juanmoretime

I use the Stan's Alpha 340 comp wheel set on my cross bike. The only tire I have used is Michelin Mud 2 and since I set them up a couple of months ago no issues. I've hit over 46 mph on a long gravel downhill and the wheels and tires performed great.
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frohrider
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by 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).
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MajorMantra
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by MajorMantra

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

bm0p700f
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by 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.

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WMW
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by WMW

MajorMantra wrote: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.
formerly rruff...

uraqt
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by 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!!!

viewtopic.php?f=3&t=114273

viewtopic.php?f=3&t=118879&start=45


C

tinozee
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by 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.

by Weenie


istigatrice
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by istigatrice

tinozee wrote: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
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