Tires blowing off Stan's Alpha 340 rims

Discuss light weight issues concerning road bikes & parts.
BobSantini
Posts: 292
Joined: Sun Jul 10, 2011 9:03 am

by BobSantini

Only that it's a tad wider and because it doesn't have bead hooks the tyre sits more like it's on a 23mm rim.
It's also reportedly a bit stiffer.
They are different alloys too but I don't know what the practical implication of that is.
r o y g b i v

pholcus
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Joined: Tue Nov 13, 2007 10:15 pm

by pholcus

I had 3 blow off! 2 layers of 21mm Stan tape, (older rim ,Spada Oxygeno wheelset), Michelin airlight tube, Veloflex 22 tire: pumped to 100 psi, bike was in the living room, overnight I heard an explosion, front tire blew off. Next day rear tire blew off!!
I used then IRC pro light tubeless for 3000 km with no problem, mounted Vittoria light tube, Conti GP TT, no problem for 200 km, then in straight line, tire at 110 psi, 15 km/h, rear tire blew off!!
Now I'm scared with tube, and I've just put on IRC RBCC tubeless for fall/Winter season.

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WMW
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by WMW

A nice thing about the bead socket design is that it makes the tire rounder and wider than a normal bead hook, which improves the ride and cornering, and maybe the rolling resistance. Typically the tire is ~2mm wider than on a normal rim of the same width. Plus the 340 rim is ~1.5mm wider than the XR200 anyway. And it's a little stiffer so you can use fewer spokes.
formerly rruff...

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WMW
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by WMW

So the correct taping method, and Veloflex and Conti GP TT coming off. Tires blowing off right after mounting *could* be caused by getting the tube pinched. Don't know how much experience you have and if you've ever had this happen with another rim.
formerly rruff...

pholcus
Posts: 47
Joined: Tue Nov 13, 2007 10:15 pm

by pholcus

mounted hundreds tires,never used tire levers, never had any issue like this with any of my wheels!e

nspace
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Joined: Fri May 21, 2010 3:08 am
Location: Milton, Canada

by nspace

Never had issues myself. I had the old ones (light ones), and rode about 4000km on them. No issues. Using both latex and butyl tubes paired with Veloflex Corsa's which I can mount by hand. I recently had the eyelets crack on the rear drive side, so now I have the newer heavier version on there. Still no issues with that setup. This is all configured with the 2 layers of 21mm tape from Notubes. Just adding to the pool of experiences.

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WMW
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by WMW

I was hoping to discover that no one had blow offs with two layers of 21mm tape, but that doesn't seem to be the case.

It would be nice if there was a foolproof protocol, but I'm not seeing it at the moment.
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dayne
Posts: 30
Joined: Mon Dec 05, 2011 10:21 am

by dayne

So i runs stans alpha 340, laced 20/24 to white ind.
I run gp400s and no rim tape but i use velo plugs.
I have done about 5000km with not one flat or Tyre roll off.

This scares me at some of the speeds my group rides hit.

Gearhead65
Posts: 112
Joined: Sat Jan 23, 2010 1:24 am
Location: Evansville, IN, USA

by Gearhead65

This just happened to me on a new style Stans 340

Conti 4000S
100 psi
been mounted for a couple months
10 minutes into a easy ride
on flat straight road.

Now I'm concerned I have some wheels that could kill me.
2015 Specialized Crux Pro
2013 BMC TMR01 custom build
2013 Cannondale F-Series 29'er, Carbon 3
2012 Cannondale CAAD10-1 custom build, 14.06 lbs
1980 Palo Alto custom build

drmutley
Posts: 344
Joined: Fri Feb 11, 2011 4:23 am

by drmutley

Different rims bit I've had alot of trouble with GP4000s blowing off... I've had 10+ blow offs over 2years...

Rims used - Dura-ace C50 7850 & 7900

I had the rim replaced thinking it was a bead issue but it still persists (thanks shimano). Mainly happens under breaking and descending, ie when rim heats up... Tyre never inflated more than 110psi. I run 95 now for more peace of mind. I've also had Gp4000s blow off straight after CO2 inflation. I've also had a couple blow off after pumping up with my (accurate) track pump if I inflate to 120psi... Commonly within a few minutes the tyre will blow off while the bike is sitting still on its stand.

On every occasion the bead is checked and seated correctly before inflation to eliminate this as an issue...

Never had this issue when using GP4000s on my Zipp 404/303s however...

thisisatest
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by thisisatest

zipp rims with aluminum brake tracks are very, very tight. it would be almost impossible to mount a tire on them with a part of a tube under one of the beads.
i know you all are going to deny this one strongly, but i would guess that *most* of these are related to having at least part of a tube stuck under the bead. often, a pinched tube is obvious after inflation, but sometimes the visual clue is much more subtle. in these situations involving a history of blowouts, after the tire is mounted but before inflation, i pull the bead back and make sure there is no tube visible. i check this all the way around and on both sides. it takes much less time than a long walk home.

drmutley
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Joined: Fri Feb 11, 2011 4:23 am

by drmutley

thisisatest wrote:i know you all are going to deny this one strongly, but i would guess that *most* of these are related to having at least part of a tube stuck under the bead. often, a pinched tube is obvious after inflation, but sometimes the visual clue is much more subtle. in these situations involving a history of blowouts, after the tire is mounted but before inflation, i pull the bead back and make sure there is no tube visible. i check this all the way around and on both sides. it takes much less time than a long walk home.


I'll be the first to deny.... Given I use green tubes, when I check the beads on both sides it's obvious if the tube isn't seated within the tyre belly... If it isn't, then it's massaged in before seating the bead...

I can understand however that if one isn't paying close attention, what u describe above is certainly going to cause blowoffs

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redhed18
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by redhed18

Red Veloplugs + Vittoria Corsa Evo SC + Conti Supersonic tubes + Stans Alpha 340 = never a single issue...
(20/24 on Extralite hubs SX/SLX ~ I'm between 155-165lb)

PS. confirming I have the older light rim...

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WMW
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by WMW

drmutley wrote:I've also had a couple blow off after pumping up with my (accurate) track pump if I inflate to 120psi... Commonly within a few minutes the tyre will blow off while the bike is sitting still on its stand.


That sounds like a tube getting pinched... which is something entirely different.

Did the tires fit tight when you installed them?
formerly rruff...

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WMW
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by WMW

Gearhead65 wrote:This just happened to me on a new style Stans 340


How was your rim taped?
Was the tire new when installed?
Was it tight?
formerly rruff...

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