I ride a titanium bike with rim brakes. It was custom made, and relatively expensive ($5,000 USD), but it is the only bike I ride, and it will last my entire lifetime, and more (it will require occasional component upgrades, just like any other bike). Plus, the ride quality is superb. I've found that, as with most things, investing in quality over quantity is the way to go. My bike may have been slightly 'less green' to manufacture, but I only need one, ever.