Corsaire

It has happened already three times at club rides. Haven't even rolled out of the pkg. lot, pop! it happens, the tube blows out right at the valve base. Can't take the high pressure, usually 155 psi.

It seems that the rim hole, where the tube valve sticks out is sharp, cutting the rubber at the valve base.

Has this has happened to you ?? What do you do to fix it ?

Corsaire

demoncyclist

A small rat-tail file on the sharp edge plus Velox rim tape usually takes care of that little problem.

Phatman

155psi? crikey!

Toothpick

Clinchers? 155 psi?? That seems like a lot of pressure IMHO. Do you really like running that much?

ultra-g

Check your rim, there might be some metal sticking into the tire or something.

Brett 12

Don't let AlanBikeHouston see this thread

I run higher pressures....I like 'em makes climbing easier.

If I had a triple I could afford to drop the pressures down and let the gears do more work.

Corsaire

It's a Vittoria high pressure tire: Diamante Pros, the Open Corsa takes 165 or so. Nothing new.

Corsaire

fogrider

agreed. easy fix. I had this many years ago on my mountain bike, it was not a high pressure issue but it would cut the tube and a slow leak would develop. I just don't think clinchers are really designed for such high pressures.

2manybikes

Agreed, this is the first step. If that fails there are rubber washers made just for this problem. You can make your own out of an old tube. Just make a washer to protect the rubber where the tube hits the edge of the valve hole.

Toothpick

News to me. Go figure. I'd think I'd be too tired from getting the pressure that high to then go for a ride. If you flat, does it sound like a bomb going off? J/K

skydive69

I'm curious as to what the recommended tire pressures are on the side of your tire. 155 seems a bit out of the ballpark for every road tire I have experience with.

Brett 12

Veredestein Fortezza SE......160 psi (23mm)

Vittoria Diamante.....160 psi (23mm)

Ritchey Open Tubulars (clincher tire).....180 psi (23mm tire)

skydive69

Thanks, I didn't realize any road tires came with such high pressure limits.

Corsaire

That's sounds like a good idea 2manybikes, great I'll make my own rubber washer out of an old tube.

Thanks Brett for enlightening the respectable forum "audience".

Corsaire

alanbikehouston

The PSI levels on a tire are NOT "recommended" levels. They are the tire company's "safety" rating based on their calculations as to when a tire might "blow off" some mythical "average" rim. Rim makers do something similar. They stamp a "safety" rating on rims based on using the rim with some "mythical" average tire.

SAFETY ratings are NOT a company's idea of the "best" PSI for actually riding on the tires. If a tire is designed to be used at 110 PSI, riding it at 150 PSI might INCREASE rolling resistance, while significantly decreasing handling, stability, and braking. And, yes...you will be replacing a lot of tubes.

Tire and rim companies do NOT suggest you actually ride at these levels. Continental posts the actual "riding" levels for its tires on its website. Because so few riders read the charts at the Continental website, perhaps Conti, and other companies, should stamp the "Best" PSI next to the safety rated "maximum" PSI.

Continental's "Best" riding levels relate primarily to the size of the tire, and assume you are an "average" weight (say, around 160 to 170 pounds). A rider weigh 120 pounds could benefit from using 10 or 15 pounds less pressure. A rider weighing 220 pounds could benefit from adding 10 or 15 pounds of pressure.

Taking Continental Gatorskins as an example, the "maximum" levels and "best" levels are quite different.

25c:

max. = 120 PSI
best = 95 PSI

Several women who weigh around 120 to 130 pounds have told me that they "hate" riding road bikes because the road shock is so painful. And, the road shock would be indeed painful, if they are riding a size 25c tire at 120 PSI, instead of the 80 PSI that is appropriate for a 120 pound rider...120 PSI is 50% more pressure than they ought to be running.

Lennard Zinn noted on Velonews.com that Pros, riding on ordinary roads stages, not on a track, or in a time trial, ride at between 100 PSI and 120 PSI, lowering pressure to around 95 PSI in the rain. And, the Pro's preferred levels are consistent with the PSI levels Conti suggests for the size 23c Gatorskin.

triggersd

Interesting thread. Anyboyd familiar with Mavic Kysrium Elites running Vittoria Pro Slicks? I'm running 120, and tip the scales at 190 right now. Um....the weight is all in my quads, calves. AND beer gut...!!!!!! ah ahahahahahha. IPA anyone?

R600DuraAce

Agree. The higher the PSI the greater the rolling resistance because your tire won't conform to the road surface. You can literally feel every single crack on the road. 110 to 120 is ideal. Tubular can go higher because they are more supple. Also, during hard cornering with too high PSI on rough road your bike will bounce around. More isn't better.

pinky

Not that I can convert bar to psi but:
https://two-wheels.michelin.com/2w/fr...111118&lang=EN

fogrider

this pretty much hits the nail on the head! I know there is a cool factor in riding on high psi but high psi does not get you good handling. and on long rides, its only going to beat you up.

berny

....and don't forget that road friction transfers heat into the tyre as does high ambient road surface temps. This expands the air raising the pressure considerably. A tyre inflated to 155 in the cool night air might end up being significantly higher on a hot day.
I also wondered if maybe the rim was 'holed' for Schrader and not Presta valves????

skydive69

Interesting information, but I am confused. Why do my Specialized S Works tires say on the side: Recommended minumum/maxium pressure 120/130. That seems to clearly recommend a min of 120 and a max of 130 with nothing about safety ratings.

galen_52657

With regard to the tire blowouts.....

I am willing to bet it has nothing to do with the PSI or the rim. I had this happen twice on my tandem - topped off the tire and a minute or two later it went flat. Each time the tube had a hole at the base of the stem - unrepairable.

I was damaging the tube at the valve stem taking the pump head off the valve stem.

Since then I am careful to hold the valve stem with my fingers and work the head off gently. Saves tubes and time....

Corsaire

I don't agree. On my Diamante Pros reads 155 recommended pressure, I tried that at first and noticed a lot of rolling resistance (actually rolled worse than my cheap stock tires), while mounted on the bike notice the tires flatten out, kind of like the radial car tires (i'm 155 lbs by the way at 5'9"), so I checked Vittorias website, discovered that their maximun pressure was 155-160 PSI (!), I tried that pressure on the Pros and VOILA! rolled like a dream! and EVEN at that high pressure is a very smooth ride (perhaps the ladies complaining about rough ride are riding AL bikes, mine is steel by the way), the tire still flattens out just a tiny bit.

The tubes blow out is NOT because of the pressure but because of the sharp rim hole, I already checked it and fixed it per a previuos poster's suggestions: using a rubber washer and duct tape.

No more blow outs.

Corsaire

alanbikehouston

You are confusing apples and oranges. The PSI stamped on tires is NOT the "recommended pressure". It is a WARNING...it is a mandatory safety notice to NOT exceed the stated PSI.

You can ignore the safety warning, and it is unlikely to "kill you". A smart company, especially a company with smart lawyers, is very conservative in calculating the safety rating for its tires.

Ride at 150 PSI or 160 PSI if that rings your bell. But, keep in mind two things about a 23c road tire:

- the PSI on the tire is higher than the proper PSI for most riders

- the Pro peloton, especially on rough, or wet roads, will ride a 23c tire at between 95 PSI and 120 PSI.

For a Diamante Pro in 23c, the Vittoria website lists as "best" 115 PSI. A lighter rider, such as yourself, could ride it in comfort at between 105 PSI to 110 PSI.

Bicycletires.com has a "chart" of best PSI's for a given tire. For the Diamente, they suggest a range of between 100 PSI (which would work well for a lighter rider) up to a maximum of 130 PSI (which would work well for a Clydesdale rider).

skydive69

Let me repeat what I said earlier: Why does it say on the side of my Specialized S Works tires: Recommended min/max pressure followed by 120/130. It does not say the word "maximum." I guess their lawyers need an education in proper tire marking.