Warning: this is only cycling related because it's about buying a bike, but I would appreciate some input.

So I'm 21 years old, but I've been using credit cards (responsibly) since like the beginning of high school. Generally I will charge everything I buy (yes, even gum) to a cash back card I've had forever, and I _always_ pay the balance every month. Every now and then, though, when I make a large purchase I get a 0% for 12 months deal, and pay the minimum every month, and then at the end of the year I'll get another 0%/12mo card and transfer it and do it again, or just pay off the balance if I can afford it. (note: I can always afford these purchases, and keep my net worth in the black, sometimes I just need to defer the payment)

Anyway, I just bought a new bike, and really can't pay for it all right now, plus I'd rather keep the $2k invested for the next year or two, and only lose $20 a month or whatever. But am I screwing myself by doing the balance transfers every year? If not, I think I'm just going to start charging everything to the 0%, so my cash is earning interest in my 5% savings account, which would beat even my cash back normal-use card.

I've had people tell me your rating only takes a hit if you sign up for several cards in a short period of time (I wouldn't consider one a year a lot, but that's me, not the credit agencies...) and that it's good to always keep a balance under your name, so I would say I'm ok, but what do you think? Will this catch up to me down the line?