Free program for converting bitrates of mp3s

Does anyone have any? I searched but I couldn't find any free ones. All I want to do is to convert the quality of mp3s.

Last I remember audacity with the Lame encoder should solve your prob. Its still free isnt it?

Thanks anyway, but I found an older version of DBpoweramp.

A little too late but try searching for Switch Convertor, they should do the job and it's free.

i have razor lame i thinke its best choise

I had big problem with mp3 bitrate. Since I have a lot of music on my hard drive I was facing disk space problems. I checked my mp3 files and noticed a large number of 256 kbps, 512 kbps even 768 kbps songs which are taking few times more space then standard 128 kbps (I think this is enough because I can't notice any differences) so I was searching a lot and finally found 4Music Multiformat Converter. I think its the best (but its not free). Every other software has some kind of defect.