This page started as a long list of ideas, but as discussions continued, the coaches realized that buying a bike is as personal experience as buying clothes, maybe more so, as most outfits don't cost as much. Instead, we will provide you with some very basic concepts, and with that direct you to your local bike shop. Each local shop sells one of the major bike brands, so which shop is as much a selection as the bike itself.
NICA rules specify that your bike must be at least a 26 inch wheel mountain bike. Currently MTB bikes come in 26, 27.5, and 29 inch wheels. All are legal for NICA use.
Our training will attempt to get you 20-25 miles per week minimum. A NICA race course is 4-5 miles, and HS riders make anywhere from 2-4 loops in a race. A box store bike (Walmart, Academy, Dicks, etc) is usually designed for approximately 100 miles of use. Using the math above we do not recommend buying a box store bike. That being said, it is legal, and has been used before.
NICA races are XC, meaning they include equal amounts of climbing and decent. This means weight matters, unlike pure decent trails. There are multiple features available for MTB, to include: tubeless tires, carbon frames, full suspension frames, dropper posts, 1X chainrings, reduced weight, etc. Any coach will be happy to discuss these options with you if you ask, but each of us will tell you we have our own personal preferences.
The ultimate answer is to talk to the bike shops. You know what you are willing to spend, and what your preferences are.
The only additional information we'll offer is that most of the major brands offer a discount for bike purchase to registered NICA riders (requires purchase in season, and registration proof). This discount varies by brand, and is as much as 25%. The second tidbit is that there is a strong resell market for bikes in the NICA community. You can consider buying used or selling if/when you want to upgrade.
Buying used carries the concerns of knowing what you want, and having an idea of what to pay for it. The following sites can help, but should not be considered gospel:
(facebook - Only MTB Swap Meet, requires permission but open upon request)