What type of brakes are best for mountain bike racing? Disc brakes are more expensive than v-brakes, but in a heavy rain they will break down. V-Brakes are becoming harder to find, but they're much easier to maintain and don't break down as easily.

What kind of brakes are best for mountain bike racing?
Look at any high end bike and you will find hydraulic disc brakes.

There will be people who argue the pros/cons of hydraulic vs mechanical disc brakes but it's hard to deny what the entire industry is putting on their most expensive rigs.

For ease of stoppage, minimal brake fade and ease of modulation - the hydraulic disc brake wins hands down.  You can hammer downhills w/ disc brakes all day long and your hands don't get tired... try that with old school cantis or v-brakes.

Plus - disc brakes will maintain stopping power in wet vs a rim brake which will definitely be compromised in wet.