As the manager of a World Cup MTB team, I am often amazed at the huge number of bike brands and designs that exist all over the world. This makes it hard to sometimes establish which brand or bike is best for you, and can be even harder when you are trying to do it online.
The first step to deciding what Mountain Bike (MTB) is best for you is to work out what kind of riding you are likely to be doing. Just because it is an offroad bike, doesn't mean that every rider necessarily intends conquering their local mountains - so be honest and realistic with yourself about what you are likely to do on the bike - the rule of thumb is that more harsh the riding conditions the more costly the bike will need to be. MTB fit into a number of rough categories, each with their own traits:
1. Road/Path Commuting - Limited off-road, used for commuting to and from the shops. These bikes will be slightly heavier, possibly steel framed and will generally have low-spec brand, or even generic parts. May have front suspension forks, but these are more for show than actually serving a pupose (Buying Guide - $50 - $250)
2. Social Off-road - These bikes share some similarity with the Road/Path rides, but we start to see front suspension forks that ACTUALLY work (although not well) and greater use of name brands in the parts mix, such as Shimano. A bike in this category is probably used on- and off-road in a 60-40 ratio. (Buying Guide - $150 - $450)
3. Light XC - This is a bike that is designed for the off-road user and will have a parts mix that reflects this. You will find a low-end name brand front suspension fork and aluminium frame and wheel set and possible even disc brakes. Some bikes may even have rear suspension at this level, but be aware that a bad rear suspension bike is worse than a good hardtail bike in most cases. (Buying Guide - $150 - $650)
4. Heavy XC/Elite XC - Expect to see perhaps a zero added to the price tag on this category, and so it should be. These are serious bikes intended for a serious rider who considers them to be a piece of sporting equipment, rather than a means of transportation. SRAM, Shimano, Rock Shox, Manitou, Race Face... these are the brand names you would expect to see providing the parts mix and the frames should come from one of the name brands too (Haro, Trek, Giant, Avanti, Gary Fisher, Specialized, Bianchi, GT, Scott or perhaps one of the smaller European brands). These are the bikes where you should also start asking relevent questions about the type of riding the owner has done, the parts that have been replaced and when, how it has been serviced and where and whether it has been raced (not that this is a bad thing). (Buying Guide - $750 - $3000)
5. All Mountain - Like the higher priced XC bikes, All Mountain bikes are precision pieces of engineering - but the flip side to this is that these bikes tend to have been punished more by the rider, as this is there purpose. They come with 4" to 6" of suspension front and rear for a reason - they are jumped, crashed, pushed and strained. If you are buying a bike in this category it pays to ask for so photos of the frame in detail, if available, and you should focus on areas of known wear-and-tear - such as pivot points, frame welds, chain stays, etc. This is a category where information helps, so search out reviews and advice from the plethora of MTB chat sites and review boards. Look to see whether other riders have had issues and whether this might present a problem to you. (Buying Guide - $800 - $2500)
6. Freeride - If All Mountain is punishment, then Freeride is 'bike abuse'. Some bikes in this range come with up to 10" of rear travel and they are designed to be launched off cliffs at speed. One popular misconception however is that this means you should avoid a 2nd hand Freeride bike. Whilst there are bikes out there that are well beyond saving - in general these bikes are built to last and as long as you are careful, you can find some great deals on a bike in this category on eBay. (see example at http://cgi.ebay.com.au/All-Mountain-Freeride-MTB-2005-GT-Ruckus-i-Drive-2-0_W0QQitemZ7247413684QQcategoryZ7297QQssPageNameZWDVWQQrdZ1QQcmdZViewItem). You need to look for name brands here, though, as it is easy to make a bike look good that isn't. GT, Foes, Rocky Mountain, Scott, Mongoose, Orange, Santa Cruz, Mountain Cycle, Iron Horse... these are all names that are hard to go past. (Buying Guide - $1000 - $3500)
7. Downhill (DH) - If you are into the gravity race scene then DH is your catagory. These bikes retail for up to $14,000 and above, so any percentage saving you can make through and online puchase might be a considerable dollar amount. The term used in most advertisements seems to be 'never raced' - which begs the question, 'then why did you buy the bike?' Certainly there are a number of DH bikes out there that are great for just bombing down hills, but at the high end of the market they are designed to race and this is what most owners do with them. Look for postings that provide a full parts list and a history of what the bike has really done. I know of at least three pro racers who sell left over bikes online, so there are great deals out there to be had. (Buying Guide - $2000 - $10,000)
8. FourCross (4X) and Dirt/Jump - These are specialised bikes designed for a particualr purpose of race or jump. They have solid builds and can take a flogging. Again, look for some sort of history of how the bike has been used and make an assessment of whether this shuold affect the price paid or your interest in the bike. An ex-Intense Factory Team 4X bike sold for $1700 on eBay, when the retail price with the parts mix was over $5000, so you can find a bargain. (Buying Guide - $900 - $2000)
Things to look out for??? There are perhaps too many to mention, but as a rule of thumb you should never buy off anyone who can't supply you photos of the parts you ask for. This may put some sellers at a disadvantage, but with a purchase of this size it is only fair that you should be able to see the bike in full. If the photo is blury, ask why. If there is mud on a section that you have heard from your research is an area of concern, ask the seller to wash the section and re-photograph it. Happy riding - Bike On.