Fifty Plus (50+) - Tire pressure whips my butt.

I rode my usual 30 miles yesterday and the ride seemed unusually rough. It's a beat up road to begin with but I was just getting rattled and fatigued, so I thought I was just tired. The next day I took the SS off the rack for a change of pace and for some reason, I decided to check the pressure coming off the scuba tank I use to inflate tires. 150 psi! O-k-a-a-a-y. Krylion carbons ride like Flintstone wheels at 150 in case anyone is interested.

At that pressure a blowout would make an AWESOME noise!

:twitchy:

:)

... I decided to check the pressure coming off the scuba tank I use to inflate tires.
:eek: Why not use a floor pump like most people?

:eek: Why not use a floor pump like most people?

+1:bike:

I have read cautions about using service station air compressors, especially on road tires because they can deliver so much pressure at large volumns of air as to be dangerous to bicycles.

At 150psi, you are exceeding the rating on some rims..............be sure you know what yours are. After allowing for pressure build up due to heat on downhill brake applications you could be way up there. HED, makers of pro racing carbon wheels have lowered their max pressure ratings lately (to 128psi I believe)after research showed 300/400degf temperatures on TDF style downhills resulting in 25+ lb pressure increases over the static put into the tire. :eek:

:eek: Why not use a floor pump like most people?
That's too much like work.

I have read cautions about using service station air compressors, especially on road tires because they can deliver so much pressure at large volumns of air as to be dangerous to bicycles.

40 years ago using service station air compressors might have been a problem. I don't think it's much of an issue today.

40 years ago bikes had and 75 psi tires and rims that didn't have hook beads.

Also 40 years ago service stations did service and had big air compressors to operate the service lift. The compressors they have today are wimpy by comparison. I doubt a modern gas station air compressor will inflate a 110psi road bike tire.

I have read cautions about using service station air compressors, especially on road tires because they can deliver so much pressure at large volumes of air as to be dangerous to bicycles.


That's only because the pressure of the gas station compressor may be higher than most bike tires. You can't "over-volume" a tire, but you CAN over-pressurize it. As soon as the pressure of the tire equalizes with the compressor, it can't fill any more. The same with the scuba regulator/inflator: the regulator is set to a specific pressure and filling stops when the tire pressure is equal with that. In my case, because of some wear and tear on the admittedly ancient scuba regulator, the pressure crept up too high.

Oops, while I was typing, Retro got it.

Most service station compressors nowadays have digital presets which only allow tyres to be inflated to about 60 psi. They won't inflate to a higher pressure than that. That's hardly adequate for riding, and even if you cop an 'over-pressure' boost by using it on a low volume bike tyre I'd think it's not likely to be a problem. You'd still end up with a tyre which is only inflated far enough to ride uncomfortably home on!

Your bike is very embarrassed. If not for self respect, do it for the bike. Get a pump...or a Huffy.

I run my scuba tanks as an air source for the shop too. Are you using just a first stage or is there a secondary reg as well?

Standard interstage pressure for scuba regs is 150 psi. As in that's what the first stage outputs. If you ended up with that much in your tire your second stage reg may be faulty and it's letting through the entire first stage output.

And before I get raked over the coals like you are I just want to FIRMLY mention that I DO use a floor pump for my bicycles..... :D

40 years ago using service station air compressors might have been a problem. I don't think it's much of an issue today.

40 years ago bikes had and 75 psi tires and rims that didn't have hook beads.

Also 40 years ago service stations did service and had big air compressors to operate the service lift. The compressors they have today are wimpy by comparison. I doubt a modern gas station air compressor will inflate a 110psi road bike tire.

40 years ago I almost always used service station air compressors for my bike tires. I had a floor pump, but didn't like all the effort it took to use it, so I'd pump up a low tire just enough to ride on it, then ride to the service station to top it off. That's how I did it for about twenty years and never had a problem. The trick was to give it very short bursts of air from the compressor tank and check with a tire gauge after every burst.

I run my scuba tanks as an air source for the shop too. Are you using just a first stage or is there a secondary reg as well?
No, one only needs a first stage. The second stage's job is to bring pressure to ambient, so that wouldn't work.


Standard interstage pressure for scuba regs is 150 psi. As in that's what the first stage outputs. If you ended up with that much in your tire your second stage reg may be faulty and it's letting through the entire first stage output.
All first stages are adjustable within a range. This one is normally set to 115 but the seat must have taken a set that raised the pressure between the times I checked it. I really should attach a gauge to it. It's an ancient USD externally adjustable piston regulator.


And before I get raked over the coals like you are I just want to FIRMLY mention that I DO use a floor pump for my bicycles..... :D
You know, if these fellow old dudes want to work harder than they need to who am I to judge them? :)

Your bike is very embarrassed. If not for self respect, do it for the bike. Get a pump...or a Huffy.
My bike is not embarrassed, it's a very high class machine sharing garage space with some very high zoot scuba gear. They enjoy their time together.

My local station has a pump that is only good for 85psi... it works for the mtb and older bikes but the 120 psi tyres need a hands on (pump) approach if I am not at my (bike) shop.

Sorry, perhaps I used a wrong turn of phrase when I said that some compressors have to much "volumn". What I actually ment was they have the "capacity" (because of the volumn of air they are capable of delivering) to arrive at the desired pressure too quickly. Even tires with hook beeds do not always seat correctly and it is quite possible with a large compressor to damage stuff before you know it.

I rode my usual 30 miles yesterday and the ride seemed unusually rough. It's a beat up road to begin with but I was just getting rattled and fatigued, so I thought I was just tired. The next day I took the SS off the rack for a change of pace and for some reason, I decided to check the pressure coming off the scuba tank I use to inflate tires. 150 psi! O-k-a-a-a-y. Krylion carbons ride like Flintstone wheels at 150 in case anyone is interested.

I don't especially like the way the Kryilon's ride even at the correct pressure. I thought they were a bit too stiff. I can't imagine them at 150 PSI.

These days many cyclists seem to go for overinflation. I find that something like 90 PSI front, 95 rear gives 28mm tires a comfortable, yet efficient, ride. (I weigh about 150 lbs; your situation may vary.)

My bike is not embarrassed, it's a very high class machine sharing garage space with some very high zoot scuba gear. They enjoy their time together.

No problem. Whatever makes you happy. :)

Part of my enjoyment of cycling comes from using equipment specifically designed for cycling. Other stuff may work, but it doesn't seem right. I like a bit of adherence to tradition. It just feels right to me. :ride:

That's too much like work.
And riding hard or climbing a hill isn't?

dude - a joe blow costs about 30 bucks. I always check tire pressure before every ride. Takes perhaps 45 seconds.
Of course - do what you want but don't expect sympathy when those tires blow off your rims. Or you get a pinch flat at 30 mph on a down hill.

No, one only needs a first stage. The second stage's job is to bring pressure to ambient, so that wouldn't work.


All first stages are adjustable within a range. This one is normally set to 115 but the seat must have taken a set that raised the pressure between the times I checked it. I really should attach a gauge to it. It's an ancient USD externally adjustable piston regulator.


You know, if these fellow old dudes want to work harder than they need to who am I to judge them? :)

Sorry, I wasn't suggesting the regular scuba second stage. Instead I was asking about something like a paint spraying second stage you add instead of the mouthpiece one. I'm using such a rig on my setup to bring the line pressure down to from 5 to 120 for using it with airbrushes, small spray guns, air nozzles and even the one time when I maxed it to 120 so we could use an air impact gun. Normally it sits at around 25 for the air nozzle but gets bumped to 40 often for the bigger motorcycle tires

True on the settable nature. And a guage would be a good idea. I'd also suggest a burst disc on your output that will let go before the bursting pressure of the supply hose. In my case the second reg has an over pressure relief that is internally set to about 20 to 25 psi over the set pressure so it serves the purpose nicely. But if the tank reg leaks with no way to vent the excess and the supply line tries to reach 3000 psi at some point you'll have lots of rubber flying around the shop at a high rate of knots!

And if you can stand the ridicule of this lot over using your tanks I guess I can too. I'm off to fill a bicycle tire from my scuba tanks just to spite them.... :D

In the olde days when I worked at a service station, that actually had service, the one and only big compressor was set at 150psi. Best for lift, impact wrench and what I called a zap gun, aka air chisel for cutting off exhaust pipes. Now we have filling stations with small little compressors. Some require a quarter to run. Either way don't believe they will pump more then 50 psi. What I haven't heard is all these compressors are fitted for schrader valves, but as I write this I do remember getting a small presta to schrader adapter. I'll have to find that thing, I'd prefer to use a compressor my self. Think my little compressor is limited to 100 psi.

"You just put your lips together and.....blow." But it helps if you have Lauren Bacall doing the blowing.

dude - a joe blow costs about 30 bucks. I always check tire pressure before every ride. Takes perhaps 45 seconds.
Of course - do what you want but don't expect sympathy when those tires blow off your rims. Or you get a pinch flat at 30 mph on a down hill.

dude, an air fill costs $4 and I can fill my tires for months, takes about 3 seconds.