squegeeboo

So I finally got a 'foot' pump, or whatever you call the non-emergecy kinds, and instead of using the free air at a hess station I pumped up my tires, and got them to their max rating of 85psi (they are hybrid tires) I went out to the grocery store and back, and it turns out I gave my rear tire a snake bite, I patched it, gave it 30 min, and took it on a 2 mile ride and the patch seems to be holding. Can I stick with the patch, or should I replace the tube with my spare tube and buy a new spare tube from the local bike shop?

Also, what are your views on the CO2 emergency pumps vs. the traditional emergency pumps?

AndrewP

If you got a snake bite puncture at 85 psi, put 90 or 95 in them next time. If 85 max is on the side of the tire, they should be able to tkae 50% over that with no problem. No need to replace a patched tube until it has half a dozen. CO2 pumping is fast and easy, but you must always carry spare cartridges with you. You might still want to carry the minipump with you for finding leaks and starting the inflation. CO2 filled tires lose their pressure quicker, so after using the CO2 on the road, top up the pressure with your floor pump before you go out again.

squegeeboo

I had read that here and on other sites, but I normally keep my pressure around 70ish, and once I got over 80 as I pumped it sounded like the rim was creaking or stretching, maybe the tube just wasn't aligned completely correctly. Thanks for the other advice for the patches and the CO2, I'll have to look at getting one of them to add to my slowly growing gear/emergency bag.

waterboy

If its a hybrid, not sure of tire size, you may end up going through a lot of CO2 to get full pressure (bigger tire - more volume). Personally, I have never seen the real need for CO2 unless you are racing. A good pump like a Topeak road morph can get you to 100+ lbs of pressure easily. Yeah, it takes all of about 1-2 minutes longer to pump, but that is just a % of the total down time due to a flat. And yeah its a couple grams more than a CO2 setup, but are you racing? Are you at 1% body fat? I 'm not. The down side of CO2 is that it costs $$ every time you get a flat, you have to replenish the supply of cartridges, it creates waste, and if you get more flats than cartridges on any given ride you are SOL. THere are many that really prefer CO2, and they cna provide thier reasons as well. Like all things- your choice is your choice.

As for the patched tube. I tend to ride a patched tube to the end of the ride, then pull it and replace with a good tube I use the patched tube as my spare. My current spare tube has about five or six patches- but hey, it holds air.

ax0n

get a good frame pump for your commute. I use a Blackburn Mountain Air, it'll do 85 PSI without a problem, which is the max for my slicks. To keep stem carnage to a minimum, I wrap my left hand fingers tightly around the head of the pump and the spokes surrounding the stem, and apply pressure to the pump plunger only with my right hand. I usually lay the bike on its side for maximum bracing effect, and it gives me good leverage on the plunger.

Get a good floor pump for home.

As far as patches, a properly applied patch will be many times stronger than the tube it's on. I've had only one puncture since I started commuting. I plan on patching and re-using until either the tube doesn't hold air, or until my actual tire shell gives out. I always put a new tube in when replacing the tire shell. If the tube still holds air, I'll fold it up and keep it in my desk at work as a spare. Otherwise, I'll cut it into 1/4" wide loops and use it for rubber bands.

waterboy

Without sounding like too much of a Topeak booster, what you refer to above is one of my reasons for really liking this pump. I am a total klutz, and have broken stems with standard frame pumps. The Topeak has a short hose, and a foot peg. The pumping action never transmits directly to the stem, so no worries about breaking or damaging the stem. It also has a simple, and reasonably accurate, pressure gauge integrated.

ax0n

Yah, but mine cost $10 and I've yet to damage a stem despite using it extensively. Actually, it's the only pump I have, period. I have a five gallon air tank for my car tires, but I haven't used it on my bikes.

Personal preference. If it works for you, great. My inferior blackburn is working fine for me.

squegeeboo

Whats this stem damage you guys keep talking about?

supcom

It seems rather unusual that you could get a snakebite on a hybrid tire at 85 psi. Hybrid tires are usually pretty large. I would check the calibration on your pump gauge.

CO2 is generally not worth the trouble for a hybrid bike. The large tire volume would require multiple cartridges to get to normal pressure. Better to go with a good frame pump. the Road (or moutain) morph mentioned earlier is a good choice.

If your tube is holding air, don't bother to replace it. You can patch a tube many times and still use it.

Stem damage comes from overzealous frame pump use. Presta valves are most susceptible to excess side loads and can result in a torn tube around the base of the valve. A Road Morph pump will prevent this.

eubi

What? How can this be? I'm not trying to be belligerent, but this doesn't make sense.

CO2 is a larger molecule than N2. What am I missing?

recursive

I don't know what you're missing, but it's the truth. I've witnessed it far too many times for it to be a coincidence. If you can explain why it happens, be my guest, but it's very noticeable.

cerewa

You're probably right that the tire and tube were somehow seated incorrectly. If you installed the tube, you probably need to be a little more careful to make sure the tube is sitting inside the tire and not pinched against the rim anywhere when you inflate. Also, don't pinch the tube while putting the bead of the tire on the rim.

If you're under 160 pounds, I think it's very unlikely you got a snakebite flat from underinflating your tires. I'm 130# or so and I've always been able to get away with running narrow tires* at 60PSI (because I only pump my tires back up to 90PSI every few weeks).


Non-emergency bicycle pumps are called "floor pumps" unless they're the type that you operate using a foot and no hands. Then they're "foot pumps".

*1 1/4 inch or so

head_wind

Consider the possibility that your gauge that said 85 psi is in error.

supcom

It's not a matter of the size of the molecule. Butyl rubber is more permeable to some gases than others. It turns out that CO2 passes through the rubber faster than N2.

I did an experiment about a year or so ago that proved this to be true. I took two wheels that had the same models of tires and tubes and filled one with CO2 and one with air to the same initial pressures. I left the two wheels sitting unused and checked the pressure twice a day for several days. The wheel with the CO2 lost pressure about twice as fast as the one with air. It was quite obvious.

If you don't believe it, try it yourself.

squegeeboo

The gauge is new, but I dont have anouther gauge unless my emergency one goes that high, which it might... Since the patch/reseat everything seems to be going well, and I'm keeping the PSI around 70, lose 5-10 a day, so it might be a slow leak still, or anouther one somewhere else on the tire.

eubi

OK, very interesting. I'm not disputing your experiment. I have dealt with molecular leaks as part of my job, and this makes no sense to me in that respect...but I then again, I have never had to contain CO2, only N2, O2, and He.

So I pull up one of my polymers books to check...I can't believe what I am seeing...permeability rates through butyl, from least to greatest...

N2
O2
He
H2
CO2!!!

Well, I'm here to learn...

HardyWeinberg

I was replacing a tube roadside yesterday and my old, repaired, spare tube had all the stuff pop out of the presta valve. How would that happen? No damage to the tube around the base of the valve.

ps-> Love to see that butyl permeability ranking! Amazing! What about latex?

recursive

Presta valve cores can be removed. I have a tool to do it. Usually it doesn't happen by accident, but I suppose it's possible.

supcom

Some do and some do not have removable cores.

CliftonGK1

That's the exact reason why so many (car) tire joints offer nitrogen inflation. Check the valve stems next time you're riding through a parking lot, and look for green caps on car tire stems. All the N2 inflation joints use them.

DannoXYZ 

Not that the low-pressure auto tyres leak much anyway; compare the thickness of an auto tyre vs. a bicycle-tube . They need checking and maybe topping off at most what... 2x a year? A lot of these tyre outfits pad their profits by touting a "performance inflation" with N2 because a lot of racers use them. Yeah right, like soccer-mum in her SUV is gonna flog her car enough to heat up the tyres to +200F degrees! When you approach the boiling-point of water, the partial vapour-pressure of water in the air increases tremendously and causes a rapid rise in pressure. This makes maintaining constant pressure and performance difficult in a race car that may cycle its tyres between 180-210F. Thus the "dry" nitrogen without water-vapour to maintain constant pressure through out the operating temperature-range. But for street cars? BAH!

As for the OP and pinched flats, if the patched tube is holding air, I wouldn't worry about it. BUT, you should out the cause of the pinched flats and do something about it rather than fixing the symptoms. Pinched-flats are caused by hitting something of a sharp angle hard enough to bottom the rim onto it and squeezing the tyre & tube into the edge of the rim. Going up driveway edges while seated with all your weight on the saddle might do it. So would hitting potholes. Speed-bumps in parking-lots can actually cause pinched-flats if you hit them hard enough. Deep drainage ditches across the road can do it. So can large rocks.

max-a-mill

one more thing no one has adressed - glueless patches are temporary where a properly applied glued patch is forever.

eubi

Yes, but I think this is a gimmick. Air is composed of:

N2, 78%
O2, 20%
Inert Gasses, 1%
CO2, 0.03%
H2O, 0.92%

I don't think it's worth it to pay for N2, when Air works just fine.

YMMV