I have a question about a component. I had the cassette replaced on my hybrid bike today at a LBS. Old one was a HG30, put on a HG50. Old gears were steel, new ones are aluminium. The young fellow at the LBS launched into a spiel about how the new gears would outlast the old ones because steel is softer than aluminium. Huh? Is there something that he was actually trying to say that just did not come out right?