first off, let me confess i’m bike ignorant… severely mechanically challenged. i approach adjusting my seatpost with trepidation. i considered it a major development when i finally became proficient at fixing a flat. as embarassing as it is to admit, much of the bike-hardware posts read like freakin heiroglyphics to me.
so with that foundation laid, be gentle to those less fortunate when replying. but here goes:
is it normal for tires to lose air on their own? without any puncture that is. what i’ve noticed is that my tires loose a signifcant amount of air over a 2-week period. in warm weather months i have a weekly routine of wiping down my bike, lubing the chain, and pumping the tires. so i never really noticed this before. but this is the first winter i’ve done regular bike training and as i only ride indoors now, i’ve slacked off in my maintenance routine. with no regular maintenace pumping i’ve seen significant deflation in both tires. i’ve checked the tubes for puncture (submerging in water) but don’t see any. even tried different tubes. still happens.
is this normal or do i have an issue with my rims or something? if its normal, how can that be?
Don’t worry, its completely normal for a tire to lose air over a period of time. The rubber that is used to make the tube is every so slightly porous (which allows it to stretch, I guess), so over a long period the tire will deflate, same as a balloon does.
Even a car tire does this, but at a considerably slower rate since the pressure in a car tire is lower and the rubber is a lot thicker.
What jason said. By the way, my tires loose 5-20 PSI over night depending on tempurature. It’s a good habit to check air pressure before every ride.
I usually check my air pressure often (every ride or two) when I ride outside, a little less often indoors. Generally, indoors just gets the quick pressure check with my index finger and thumb. The tires will loose air pressure over time since there is no way to have 0% leakage. I don’t know what you mean by substantial, and I also don’t usually go two weeks without putting air in my tires, so I’m not sure how much I generally see. I’ll see maybe 10 psi or so over a few days while I’m indoors.
One thing is to make sure the valve is closed. Some tubes have removable valve cores so that extenders can be put on them, these can loosen a bit, which would increase your pressure loss. You can distinguish the removable cores from the fixed ones by a change in color and shape. The removable ones I’ve seen have flattened sides and also are silver.
Other than that, as long as you’re not loosing a lot over a couple of days (like 50% or so), I wouldn’t worry about it. But then again, I’m no bike expert either.