Originally Posted by
prathmann
Throw away the 'dustcap' when you first install the tube and the process is a bit simpler - the only function of it that I've found is to keep the sharp end from puncturing the tube as it get jostled in your bike bag. There's no way for any dust to get inside the valve once it's screwed closed.
Then either stop being 'ham fisted' or switch to Schrader valves (harder if you have deep rims that require extra long valve stems).
The other function of a dust cap is to keep the valve end clean. If you ride in wet grit or mud, your valve will get dirty. Then when you go to pump, you pump a little grit into the valve. This grit can keep the valve from seating properly and then you get a slow leak you can't find or a damaged valve. I've had this happen. The no-cap thing started with racer types who don't like the weight of it (!), or the time it takes to put it off and on if they're trying to get a quick pump-up for a slow leak. It doesn't weigh anything and in the long run, it protects your valve. However in the short term, you get derision from the same people who never wear mirrors because they're faster than anyone and don't have to care about who's behind them.
You're absolutely correct about having caps on the tubes in your bag. I've had an uncapped tube cause an abrasion puncture in an adjacent tube. However if you don't replace the cap on the tube after installation, you'll lose it and then what are you going to put on the tube after it punctures, you patch it and then put it back in your carry bag?
Mr. Practical here who rides well enough that I don't have to care about what anyone else thinks about my choices.