Bicycle Tutor

I had a puncture and i replaced the tube. About 10km later the tyre and tube(which was still inflated) just burst out from the rim and the rim was damaged and the wall of the tyre was cut in two places. The incident occurred riding on road. Why did it happen?

Was it because i did not fix the tyre and tube securely into the rim or was it that the tube was underinflated?

Sorry to hear that happened, hope you are ok!

It could be that the tyre was not properly seated on the rim. When inflating a tire, it's a good idea to put a little bit of air in just to fill in the tyre's shape, and then inspect it all the way around to make sure the tyre is evenly seated before you continue inflating. If it's slightly out of place, it could bulge and slip off the rim like it sounds might have happened to you.

Most often the tyre will have a line all the way around that lines up with the rim to make it easier to position properly. Once you're sure the tyre is seated properly you can continue inflating to the recommended pressure.

Some more tips on fixing a flat here: http://bicycletutor.com/fix-flat-tire/