Tires & Inflating

[surgtech1956]

This is the first time & first bike where I've inflated my tires before a ride. The only time I didn't - I got a flat. Should I be letting a little air out after I ride? Why inflate the tires before every ride?

[OakLeaf]

Nothing seals perfectly, and the thinner the tube and the higher the pressure, the quicker air will leak out. That's why race teams inflate their tires with nitrogen - not (as some will tell you) because of temperature issues, but rather because nitrogen molecules are larger than oxygen and other gases in air, so it leaks out more slowly.

I usually lose 10 psi overnight from my 700x23 tires with inexpensive tubes.

On the other hand, CO2 molecules are smaller than either oxygen or nitrogen, so when you inflate a tube with a CO2 inflater, it will go flat much more quickly than usual. Some people actually let all the air out of a tire once they get home after they've inflated it with CO2, and re-inflate it with room air.

Your other bikes lost air too, just apparently more slowly with the heavier tubes and lower starting pressure.

[lph]

Yup. You don't necessarily need to inflate before every ride but you do need a minimum pressure to prevent flats. In skinny tires that pressure is quite high, and leaks out easily, so you need to top up more often.

I rarely bother to top up the tire pressure on my commuter w/fat tires, but I'm always shocked (well, slightly surprised :rolleyes:) at how low the pressure has gotten when I do.

[Catrin]

I always check my tires before every ride, for all of my bikes. It is interesting to see the differences between them, my mountain bike tires only lost 2 pounds of pressure after sitting for 2 weeks, while my thinner tires can lose that much overnight.

Bicycle tires aren't air tight and do lose air slowly each day. I may not HAVE to check/air for every ride when I ride most days, but I do check. The act of checking does cause me to lose a little air, but to me it is worth it to know my tire pressure is where it should be before hitting the road. I am far from fast at changing tires, and it is a b*tch to even get the wheels off my Gunnar that I want to do all I can to avoid a pinch flat. At least when something happens I won't blame myself for it due to having too low pressure :cool:

[surgtech1956]

Thanks for the info. I just have to get into the habit of checking them. Does weather make any difference - hot, cold, humidity?

[spokewench]

Yes, heat will cause them to be more inflated, cold the opposite. Humidity, I'm not sure??

Anyone?

[marni]

In addition to checking your tire pressure before the ride, another good habit to get into is after the ride, check your tires for slashes, things stuck in, rocks, glass chips etc. after each ride. I also wipe down my rims with a clean dry rag to get rid of any oil dirt etc. picked up on the road, and wipe off my brake surfaces. I do this because I (being admitedly obsessive, but also because I ride solo out in the country away from things like bike stores, gas stations and mechanical help, and because I am so abysmally slow at tire changing) don't want anything to complicate my ride.

I also wipe down the chain and jockey wheels on the derailleur, after every ride and relube about every 150 miles.

I grew up riding horses, and just like I would never put a horse "rid hard and put away wet", I won't do that to my bike either.

The routine takes me at most 5-7 minutes, and by that time my breathing has normalized, the majority of bugs, sweat and sunscreen have dripped of and I have finished my last bottle of water.

You take care of your equipment because it takes care of you.

[lph]

Yes, heat will cause them to be more inflated, cold the opposite. Humidity, I'm not sure??

Anyone?

Yup, I had a mtb tube and tire explode on me with an almighty bang last summer. I had inflated it (a bit too much) that morning, it turned into a hot summers day, and I left it lying in the sun in the afternoon by the beach. The noise sounded just like a gunshot, almost gave me a heart attack :eek:

If you're not a heavy rider you don't have to inflate to the absolute max. Tires with high pressure will roll more easily, but only up to a certain point, after that you start to bounce about too much. I read somewhere that you should be able to see the tires flatten just a little bit under your weight once you're on the bike.

PS. I doubt humidity makes a difference given the same air pressure, since the tube is virtually airtight.

[surgtech1956]

Thanks for all the advice. Our roads here are terrible, if its not pot holes, its some stones & ??? on the side of the roads. Like anything else, its just a good habit to get into. :)

[RubyTuesday]

Interesting read for a newbie. My sister got a flat by leaving her bike in the car when it was 100 degrees outside. I guess those old molecules just got to her tire.

I never realized that you had to pump up the tires so often either. I didn't do it for the first five or more rides on my new bike. When I finally checked the tire pressure it was 60! Ooops.

Thanks for the info.

[Owlie]

PS. I doubt humidity makes a difference given the same air pressure, since the tube is virtually airtight.

It might make a difference if you fill it with "wet" air and leave it in a warm place (vs. dry air in a warm place)...water vapor is a very non-ideal gas!

(And if I had a chance, I'd fill my tubes with argon. :D )

[Don Deitz]

While on the topic of inflating tires, has anyone had much success with pedal-driven airpumps lasting very long? It seems like mine last 1-2 years at most.
Either the connector to the valve stem breaks or the foot pedal ruins the compressor tube.

Any suggestions for a good brand?

Thanks,

Don Deitz