What do those designations mean?

[Owlie]

What's the difference between XC, all-mountain, and sport-type mountain bikes?

[Irulan]

It usually has to do with the amount of travel and differences in geometry. A trail bike, or all mountain is going to have more travel (5" or so ) than an XC bike (3-4") and will be more slack in the geometry. More slack is less aggressive/forward in geometry; the "sit up and beg" verses 'XC race" style. I have heard "sport".... I have not a clue but it makes me think of a Sports Authority style box store bike.

[Owlie]

It usually has to do with the amount of travel and differences in geometry. A trail bike, or all mountain is going to have more travel (5" or so ) than an XC bike (3-4") and will be more slack in the geometry. More slack is less aggressive/forward in geometry; the "sit up and beg" verses 'XC race" style. I have heard "sport".... I have not a clue but it makes me think of a Sports Authority style box store bike.
As far as I can tell, the "sport" is a more "general public-friendly" bike. It'll do a little of everything, but not be very good at it. The "sport" series from at least one particular manufacturer appears more upright too.

[thekarens]

The XC is less upright. I actually prefer it, but I know a lot of people like being more "in" the bike instead of on top.

[indysteel]

So, does XC mean a less upright position?

Generally, yes. The top tube on my Santa Cruz Juliana, an XC bike, is longer than any of my other bikes (my road bikes aren't particularly aggressive). It can feel uncomfortable if I'm just tooling around on the bike. On the trail, I don't notice it at all, but that's mostly because I am rarely seated for long. The longer cockpit gives me plenty of room to manuever--and that's what you can expect to do on an XC bike. An XC bikes seems like the right choice for you in terms of weight (trail, all mountain and downhill bikes are all heavier than XC) and travel, although based on what you've shared in terms of the off-road riding available to you in S.C., I don't know that you'll benefit from a FS bike over a HT. I guess it depends on where you ultimately want to ride the bike.

[indysteel]

FS will be helpful with roots; arguably not essential, but helpful. Sand, maybe not so much (you've mentioned in the past wanting a bike to ride in the sand).

Certainly, you can set up the suspension to match your style of riding and the trails you typically ride. Some bikes allow you to essentially turn them off. I can turn my rear suspension off, and some people like to do that for long climbs or any period where it's not needed, as it lessens pedaling efficiency. Your bike's front and rear suspension may have additonal settings that you can use.

[Irulan]

The geometry gets more slack left to right

http://www.singletracks.com/blog/wp-content/uploads/2012/04/xc-v-trail-v-dh-wide.png

excellent article, with this illustration

http://www.humankinetics.com/excerpts/excerpts/choose-the-right-bike-for-your-riding-style

http://www.humankinetics.com/AcuCustom/Sitename/DAM/050/12art1_artX.jpg

[Irulan]

There are trails with a lot of tree roots I might try. Though that may be difficult?

I'm hoping to travel a little with this bike.

I will need to make an appointment with my fitter/mechanic in Charleston and have him take a look at the suspension. It seems it can be set differently for different uses? I'm certainly going to be very gentle with the bike and my body in terms of where I ride it until I get some actual instruction.

mmm, that would be a slight misconception, that suspension can be set for different uses. If the suspension is set up correctly, it is set for your body weight. How fast the rebound occurs can be set, which may be what you are thinking of. I use a slower rebound for more technical stuff, faster for smoother trails. In some bikes, you can lock out the front or rear suspension for extended climbing. Also, with some front forks the amount of travel can be adjusted which will change how slack the head angle is in addition to giving you more travel.

[Irulan]

The XC is less upright. I actually prefer it, but I know a lot of people like being more "in" the bike instead of on top.

Having owned and ridden both types, where you will feel the most difference is descending, especially anything steep. It's the difference on feeling whether you are going to go OTB or not on a descent. There are other more subtle differences,but that is one of the main ones.

[thekarens]

Having owned and ridden both types, where you will feel the most difference is descending, especially anything steep. It's the difference on feeling whether you are going to go OTB or not on a descent. There are other more subtle differences,but that is one of the main ones.

True, Houston doesn't have any major descents, so it's not something I've had to deal with yet. Getting behind the saddle works fine for the trails I've been on so far. Might be different if I went to Austin where they have hills. Might need/want to invest in a drop seat for that :-)