Repairing a twisted front rim in emergency? The front rim got somewhat twisted. I do not have here the rimmer or the small tools to adjust the pins. According to my friend's version, the outer tire and the inner tire are in fine condition. The twisted rim apparently resulted from riding the bike with plastic bags inside the tire about 10km due to a flat. I think the story of fine-conditioned inner/outer tires sound too good so there may be more problems with the tire. It is at least a fact that the tire rim is twisted. 

Some emergency tips to adjust the rim?


is it easy to do a rim with proper tools on the road?
can I use 26" rim to the front wheel and 28" rim in the position of back tire?
can the 28" bike use 26" tires of the proper width? The bike has outside derailleur and rim brakes.
It is a professional's job to true and tension a wheel. One worth learning to do for yourself, but not one to jump into without knowledge and the proper tools. No it is not easy to do on the road, except as an emergency " get you home" fix. Very likely, a amateur attempt to fix it on the road will result in more damage. 

In addition, a "somewhat twisted" rim from riding without a tube for an extended period usually indicates a problem with the metal of the rim being physically bent. In order to true a wheel, you add tension to each spoke until the rim is straight and the wheel is round under high tension. But if the wheel doesn't start straight, the spokes will not be tensioned evenly, and the job will not last for more than a few hours, or days if you are lucky. It requires skill, and quality tools, or you will make the damage worse. I would suggest in the future, walking the bike om, rather than risking this kind of permanent damage.

If you have disc brakes, you may be able to run different sized wheels in the bike for an emergency, but it will change how the bike handles, and may affect the safety of riding the bike.

If your bike has brakes that grab the rim to stop, then you must use the original size rim to replace it, because otherwise you will have no brakes.