Bikes and their components are made to achieve different purposes on XC, FR, DH. What exactly are the differences on the bikes' designs? How can I judge a bike's appearance to tell if it is for XC or FR or DH?

Putting this very simply (very, very simply) an XC bike will be built for long rides with high saddle postion, small travel forks and will be as light as possible. They may also have very limited rear suspension. DH bikes are built like tanks with large amounts of travel front and back. FR bikes are somewhere between the two.

what about "All Mountain" bikes ?

Their the between XC and FR.

Hi DMN, do you mean ...



Cross Country: XC
All Mountain: AM
Free Ride: FR
Down Hill: DH

Ride-Distance Saddle-Position Shock-Travel
XC longest highest shortest
AM long high short
FR short low long
DH shortest lowest longest

Then, comparing hard-tail and full-suspension mountain bikes, which type if XC or DH?

Try not to include distance as a factor. The types of riding/bikes relate more to the type of terrain and speed required over that terrain. Shock travel and saddle position are things that come with the territory with the type of riding required.

Type::::Terrain::::Saddle Height::::Travel
XC::::least technical, most uphills:::::highest:::::shortest 2-3inch
AM:::::"all terrain", short drops:::::mid::::-pretty long 4inch
FR:::::few uphills, very technical + freq drops:::::low:::::long 5-6inch
DH:::::walk uphill, big drops, most downhill:::::lowest:::::longest 7-9inch maybe more

Spot on.

The definitions of FR bikes anf DH bikes is actually very hard to decide, they tend to cross over. Some FR bikes are built like tanks..... Karpiel Army for one, huge amounts if travel and a beefy heavy frame. Then some DH bikes are built pretty light, you have to remember that in all forms of racing the riders are trying to build reasonably light bikes, look at things like the Cannondale Gemini and Orange 223. In some ways FR bikes and DH bikes can overlap. The majority of times you can tell the difference by the angles. A DH bike will have slacker angles than a FR bike usually.