Originally Posted by
hig4s
To add to what was said, after trail, it is generally enduro, all mountain and downhill, and what you get as you step up is generally more suspesion, slacker head angle (for more downhill and speed stability), and more sturdy construction. Generally Trail bikes would be FS and have 120mm to 140mm, enduro 150mm to 170mm, All mountain 160mm to 180mm and downhill 200mm or more. Of course each manufacturer has their own definition.
As far as FS trail bikes go There are a couple fairly decent entry level ones for under $2k, but generally over $2k. I think the price point where you get the most bang for the buck for FS is from $2.7k to $3k. The difference from a $1900 dollar FS to a $2500 and then to $3000 are huge jumps in what you get, after $3000 the increase in quality seems smaller for the money.
Many companies do not call their HTs trail bikes, but certainly many are a good fit for trail riding. For HT I think the bang for the buck price point goes from $1000 to $1300. I would look for a good 120mm full air fork. Most brands by the time you get to a full air fork, already have decent level on the rest of the components.
hig4s pretty much sums up what I was going to say about the underlying logic in class designations, except that I have more often seen Enduro as the the slacker/more travel option compared to All Mountain (AM), as it is marketed for enduro-style racing. So in my experience the spectrum more often goes from XC > Trail > AM > Enduro > DH. But again, not every company uses the same definitions.
As far as the tire sizes... yeah, it can be a bit of a religion for some folks. The difference between a 27.5" and 29" is not night and day, but it is there. the larger wheels do roll over things better, but the smaller wheels can allow a design a little more maneuverable, or as some people say, more "playful". Not surprisingly, the differences are not as stark as with comparing 26" vs 29".
27.5+ is kinda still working itself out. The initial idea was that a 2.8-3.0-ish tire would allow very low pressures and make riding most trails easier. On its face that made sense as people had been realizing the benefits of low pressures that tubeless had allowed in more standard size tires. And to a large extent it does work out that way. The problem it has run into for
some riders is that once you go much beyond 2.4 or so, the limit you run into for pressure is not pinch flats or rim strikes, but the instability of an underinflated tire. This is not much of an issue of you are not an aggressive rider (and this tire size was, in fact, marketed as more "beginner friendly), but as you start to really stuff the bike into corners and land on less than perfect ground, you are losing some control. This is somewhat born out by the fact that most Enduro and DH racers stick to tires in the 2.3-2.5 range. Of course, you can get around the squirmy tire issue by either increasing tire pressure or beefing up the sidewalls. The former kind of defeats the whole point of plus tires, and the latter makes the tire heavy, as well as less compliant (which negates some of the benefit of the lower pressure). However, for less aggressive riding, they can make a lot of sense, and you will often see them recommended for off-road touring. In fact that is actually what the very first plus size tire and bike (the 29+ Surly and Knard and Krampus) were marketed to. I see that the trend has lately been going to something like ~2.6" as the happy medium between standard and plus.
As far as what would fit the bill for you? Yeah, in your price range you are definitely looking at a HT. While HTs are generally not parsed as much as FS bikes in terms of labeling, there are differences. Some are more XC race-oriented, some are are more Trail oriented, and some even considered AM. It sounds to me like you are looking for an XC or Trail HT. I would think either 27.5+ or 29. 27.5 if you want more comfort, 29 if you plan to ride more aggressively on the downhills.
Take all of this with a grain of salt. I am sure someone has exactly the opposite experience with plus size tires. And to be fair, I have only demoed plus size tires, never owned one. However, just from riding standard tires, I have always been skeptical of the performance gains over a TRUE 2.4" for aggressive riding (plenty of claimed 2.5s are actually a bit smaller).