I started out with bottle generators when I was in the military in 1976. They annoyed me due to the added effort needed to propel my bicycle. They also slipped in foul weather. I never worried about wearing out the sidewalls. In 1980 before I transferred to Germany I bought a generator that mounted to the BB were the kickstand would go. Because it pressed against the tread of the tire it didn't slip as much as the bottle generators and there was less needed effort compared to the bottle generators. The BB generators wore out quicker than the bottle generators. When they were no longer available for purchase I didn't go back to the bottle generator. I have had a Schmidt Son 28 dyno hub for near 12 years. I don't notice the difference between off and on and foul weather is not a problem. I recommend dyno hubs to people over batteries or bottle generators.