Originally Posted by
carhea
I have always kept the bike indoors and I only clean it with soap and water on the frame. Also when using it on the trainer I have a sweat guard I use to keep the sweat from dripping all over the frame.
That's not fatigue, that's corrosion and perhaps your sweat guard isn't doing the job. Concentrated salt solutions (e.g. drying sweat) will cause that kind of corrosion on aluminum if it's not painted properly.