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 ) 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

[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?