Replace or patch inner tubing? I'm 16 this year and I commute to school on a regular basis on a second-hand Urata Avanteguarde (about 2-3 years old.) I kept getting flats on my rear tire, but by the time I has isolated the problem to a needle sized puncture in my inner tubing, I had already torn my tire beyond repair. I've already bought a replacement tire, but i wonder if it is completely necessary to replace the inner tubing? If not, what are the risks of doing so ?

I am relatively new to road bikes, so I do apologise in advance if there is anything I'm missing out, or if this is a stupid question in general.
Some terminology first.


TUBE is the doughnut-shaped ring that holds the air (inner tube)
TYRE/TIRE is the bit with the tread, and on your bike this holds the tube in place.


So you got several punctures in the tube caused by something sharp in the tire 

You damaged the tire somehow and have a replacement.  Now you've removed the sharp thing from the tire, and you want to know if the tube needs replacing ?

ANSWER Probably not.  If the tube holds the air pressure its fine.  If the tire has worn tread (ie to the point you're through the rubber and riding on the threads, or if it feels really thin to your fingers)  or if the tire has a cut or significant hole, then replace it.

I'd recommend you throw a spare tube in your schoolbag, along with a mini-pump and tire levers if you need them, and a tool for your axle nuts if required.  This will let you change tube on the side of the road, and patch it at home later. 

Replacing the rear tyre should reduce the frequency of punctures too.  The rear wheel suffers punctures about twice as fast as the front wheel.

Also, you might consider avoiding things that generate punctures too - which means not hopping kerbs/curbs, not bouncing through potholes, and going around patches of glass on the road/cycleway.