Mountain Biking - What's the difference between a XC bike and a ATB?

I notice that fulls suspension designs for cross country are different from FS designs for mountain biking. Why?

What's the difference between mountain biking and XC biking? Can you use a XC bike for mountain biking and viceversa?

Mountain biking and XC bike are one in the same, each category in mmountain biking has their own style of bike.

Mountain Bikes include XC (cross country light weight), FR (freeride, medium to heavy weight), DH (Downhill, heavy to veeeeery heavy weight) and Trail bikes (do it all medium weight bikes).

To further extrapolate on Danka's point, Mountain Biking is a broad classification, and encompasses all riding done off-road. The bikes for each sub-classification are specialized just like in many other sports. (Car Racing comes to mind, Nascar, Formula 1, Dirt Spints, Drag ...etc.)

The two ends of the spectrum are XC (cross country) and DH (Downhill).

XC bikes are designed to be lightweight, and fast through varied terrain, including long sustained climbs, nothing too technical, minimal jumps. These are your long distance athletes.

From there, you can go to Recreational riding which are XC bikes with a little more heft (duability) to them. This is the type of riding that most riders experience.

Then you can get into Freeriding. This includes jumps, drops, still climbing to the top of the mountain. Also included is "Urban" which is riding agressively through your city, looking for stair gaps, loading docks, curbs, ...etc.

You've also got your Dual Slalom and Mountain Cross. These bikes are like BMX bikes on steroids. Not quite DH strong, have less travel, but designed to handle jumps and tight turns.

Then you've got your Trials riders, these guys have highly modified bikes and do an amazing amount of tricks, hopping up onto obstacles without "dabbing" (putting a foot down).

Then off course, you've got your extreme Freeriders who do cliff drops (30-40 feet drops). North Shore type riding where you ride a 1'0" wide man made elevated trail network with teeter totters, drops and some crazy stunts.

And finally, your DH racers. These bikes are designed to go down a hill in the least amount of time. The designs now have up to 9 or 10 inches of suspension travel, over built and heavy bikes designed to handle any terrain.

There are more, but I'm tired of typing.

L8R

To further extrapolate on Danka's point, Mountain Biking is a broad classification, and encompasses all riding done off-road. The bikes for each sub-classification are specialized just like in many other sports. (Car Racing comes to mind, Nascar, Formula 1, Dirt Spints, Drag ...etc.)

The two ends of the spectrum are XC (cross country) and DH (Downhill).

XC bikes are designed to be lightweight, and fast through varied terrain, including long sustained climbs, nothing too technical, minimal jumps. These are your long distance athletes.

From there, you can go to Recreational riding which are XC bikes with a little more heft (duability) to them. This is the type of riding that most riders experience.

Then you can get into Freeriding. This includes jumps, drops, still climbing to the top of the mountain. Also included is "Urban" which is riding agressively through your city, looking for stair gaps, loading docks, curbs, ...etc.

You've also got your Dual Slalom and Mountain Cross. These bikes are like BMX bikes on steroids. Not quite DH strong, have less travel, but designed to handle jumps and tight turns.

Then you've got your Trials riders, these guys have highly modified bikes and do an amazing amount of tricks, hopping up onto obstacles without "dabbing" (putting a foot down).

Then off course, you've got your extreme Freeriders who do cliff drops (30-40 feet drops). North Shore type riding where you ride a 1'0" wide man made elevated trail network with teeter totters, drops and some crazy stunts.

And finally, your DH racers. These bikes are designed to go down a hill in the least amount of time. The designs now have up to 9 or 10 inches of suspension travel, over built and heavy bikes designed to handle any terrain.

There are more, but I'm tired of typing.

L8R

Ok I notice that the differences between DH, FR and XC, ATB are obvious. Between XC and ATB the differences are not. I notice that on a XC bike the suspension goes attached to the top tube not like an ATB or Mountain bike. Question is Does that make a significant difference?

Possibly this should go to the mechanics forum.

An ATB used to be just a generic term for an off-road (all-terrain ) bike and meant the same bikes commonly called MTB's. It was never as popular, and recently some retailers/manufacturers are mis-using the term to describe a less robust MTB.

different suspension designs are not always exclusive to the sub-categories of mountain biking. generally, xc bikes focus on efficiency, meaning pedaling efficiency, and also lightweight. freeride and dh rigs care less about pedaling efficiency and are built to be handle abuse.

Rich summed it up. ATB is a generalization of mountain bikes. It's a matter of semantics between an MTB, and an ATB.

There are a number of suspension designs in ALL categories of riding. You've got you single pivot, your 4-bar, your rocker arm, your uni-strut, your flexible chainstay...etc. Shock locations all vary with different designs.

They're all ATB's or MTB's or ?(whatever you want to call them), I call them mountain bikes.

L8R

I think there's a lot of confusion with naming and categorizing particularly for new riders. Suspension designs are dictated by the manufacturer and have little to do with a bikes category. With the exception of travel. XC bikes typically have less travel and DH has typically the most travel.
In regard to your question of XC vs. ATB my understanding is that XC bikes are typically the lightest, have at most 3" travel if any (although this is being pushed higher with more efficient suspension designs), and are often designed with racing or epic riding in mind. The ATB is more a general purpose or all trail bike. Typically a bit heavier and has 4-5" travel (again, not a rule). You can abuse it a bit more without worrying about breaking it. You can take it everywhere a XC bike could go and more. Depending on you level of fitness it may be too heavy for an all day outing and definately not fit to be raced. I think this catagorization is more accurate for high-end bikes though. I kind of consider an ATB to be a "baby freeride" I guess.