how often do you pump yours tires?

yep, should be at least once a week for my road bike. My town bike's lucky if it gets pumped up once a month or less!

A track pump by the front door helps, I found. Easier to remember and running the right pressure makes for a better ride. Agreed with the various points on low volume high pressure means more pumping. I keep my GP 4000s at 110 ish and they'll drop maybe 10 a week or so. My brompton with marathon plus seems to hold the pressure better, so 90 for a week or more, mountain bikes fortnightly.

every ride for me,

As with Gkam i pump mine up every ride and deflate after each ride as i store my bike off the ground - not that that makes any difference - i just dont like the tubes being constantly at a high pressure

before every ride - if your tubes hold air too well, you are not going fast enough (they are too heavy) and if you do not play with your pressure you will never go fast enough...

Not any other reason than i store mine in my travel case, Saves having a bike just lying around my room, So deflate and pack away. Bit of a pain, but it keeps the place looking tidy

I pump up my tyres every time I clean the bike.

So after rain basically.

I suspect gkam also stores his tongue in his cheek.

gkam,

is that an anti-theft measure or for other reasons?

I do mine every ride, then deflate when i come home and store the bike in my bedroom

I will add my experience of at least once a week for my road bikes, and every couple of weeks for my MTB

Life without performance bikes is a lot easier

I ride a bike everyday and most weeks do not pump up any tyres.

For example yesterday I pumped up the back tyre of my Bullitt Cargobike for the first time since I fitted a new tyre on 18th March. The tyre is a Schwalbe Marathon Plus Tour 26"x2"

On my road bike I run Schwalbe Marathon Classics 700cx28mm and again I would be surprised if I pump them up more than once a month.

On my Peason fixie I run 700cx25mm, again I pump them up less than once a month.

All these bikes get used multiple times a week and due to the road quality here I don't let them get soft cause otherwise I always get pinch flats.

I run cheapish inner tubes (Continental Quality Road Pack of 5 Inner Tubes Cross 28's from Wiggle).

So my guess is that small diameter tyres have 2 disadvantages a) higher pressure so more likely to loose air b) smaller air cushion so need to keep pressure higher and more consistent to avoid pinch flats.

I'm happy to stick to bigger volume tyres

I ride two or three times a week and pump them up before every ride.

Probably a couple of times a week. Your tubes will loose pressure regardless. More so when they are latex. And as simon says the presta's seal from the pressure of the tube. If they were losing pressure every couple of days then you may have picked up a slow puncture.

The narrower the tyres, the smaller the volume and higher the pressure, the more often they need to be re-inflated. 12 psi from 120 in two weeks is a lower rate of loss than I'd expect, so you are doing well. I pump up 90 / 100 psi 25 mm tyres once a week. 26 x 1.6 " tyres on my winter commuter at 80 psi only need pumping up every fortnight, at most.

The loss of air is through the fabric of the tube. There's nothing you can do about it.

Some tubes lose more than others but 12 psi over a fortnight isn't so bad. If it was overnight I'd be more concerned (excepting latex tubes, which are considerably less airtight than normal butyl ones).

The cap is only keeping dust and crud out and the threaded locknut prevents it opening accidentally, I believe it's the pressure of the air inside that keeps it closed.

twice a week sometimes 3 times.

TT bike tyres deflate every 3 days so i just put them back up to X PSI.