MTB Frame Categories & Disciplines

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MTB Frame Categories & Disciplines

Postby ChiliPepper » Thu Jan 02, 2014 6:56 pm

Mountain Bike Frame Categories & Disciplines:

Below is a broad-spectrum of design categories and riding disciplines that mountain bikes/bikers fall into for the general public. Please be aware that the information below does not cover all aspects of mountain bike design and disciplines, but provides a baseline to understand the basic difference between each bike type below.

Frame Categories:

Many riders know that mountain bikes are split into 4 main design categories. Each category offers a unique set of design challenges for the manufacture since today, the design category does not determine the riding discipline. An example of this design challenge is you will have riders using full suspension bikes for downhill racing; however you will also have riders using hardtails for the same purpose. This stated fact has made the industry design a number of specific frames for a specific use. However, regardless how many different frames are created, they generally fall into one of the 4 main categories below.

Fully Rigid - This is a mountain bike that has no front or rear suspension. In some cases, the bike frame is design only for rigid use where front suspension would make the bike ride and feel unstable due to its geometry.

Hardtail - This is a mountain bike with no rear suspension, but is designed for the use of a front suspension fork. The range of suspension travel will be determined by frame geometry, but in many cases, you can convert a hardtail to a fully rigid with minimal problems.

Full Suspension (Dual Suspension) - This is a mountain bike with both front and rear suspension. The bike consists of a frame and rear linkage with single or multiple pivot points to allow movement of the rear wheel. Again, the range of suspension travel will be determined by frame geometry.

Soft Tail - This is a mountain bike design that is rather unique and a cross between a hardtail and full suspension bike. Soft tail bikes have very small amounts of rear suspension that is controlled by flexing the frame rather then utilizing a rear pivoting linkage.

Bike Frame Oriented Disciplines:

Mountain bike frames fall into several different disciplines that are usually defined by the type of terrain, not the rider. This is not to be confused by a "Rider" selected discipline which is completely different in respects to the design and build of a mountain bike. An example of this statement is that; a person whom practices the discipline of "Trials" can ultimately perform many aspects of this discipline on a number different bikes (i.e. XC, Freeride, etc) however, the bike selected may not be designed to handle the related frame stress that would be endured during such maneuvers.

With that said, all of the above frame categories fall into one or more of the following disciplines listed below. Please understand, I have not covered all related bike disciplines, just the majority of what we see when riding in the woods, on single and double tracks, & bike parks.

Cross Country (XC): Mountain bikes that fall into this discipline are designed around two main factors; weight and pedaling efficiency. Many of these bikes are designed with relatively small amounts of suspension (front and rear) and have steep head and seat tube angles to allow a more forward leaning body position during riding. They are typically fabricated from Aluminum, Carbon-fiber and/or bi-metal mixtures to achieve the lightest possible frame but maintain strength for its design purpose. Cross country bikes typically have 3 selectable front sprockets along with a 9 speed (cog) rear cassette allowing for a huge variation of pedal torque vs. gear inch travel.

Below is a typical bike build for XC frames that are oriented for this riding discipline:

Frame Design: Typically Full Suspension.
Frame Geometry: Head Tube Angle 70 degree; Seat Tube Angle 73 degree; Wheelbase 43 inches.
Average Build Weight: 20 to 30lbs depending on component selection.
Suspension Travel: 3 to 4 inches for both fork and rear shock.
Suspension Type: Air fork and rear shock.
Wheel Setup (Front): Lightweight XC rim with 32 hole QR hub.
Wheel Setup (Rear): Lightweight XC rim with 32 hole QR hub.
Tire Size Range: 1.9 - 2.3 with a durometer of 65 (average).
Brakes: Cable & hydraulic brakes with 6 inch disk rotors (front & rear).
Crank Arms: 175mm - 180mm
Chainring: Three sprocket setup ranging from 24t - 48t.
Rear Cog Set: 9 speed cassette ranging from 11t - 32t.
Stem Length: 70mm - 130mm; 6 degree rise (average).
Handle bars: 23" - 25" width; 0" to 1.5" rise; 5 degree rearward & 4 degree upward sweep (average).

All-Mountain (AM): Mountain bikes that fall into this discipline are a cross between XC bikes and FR bikes. They are designed for efficient pedaling but have slightly heavier frames to handle more aggressive technical riding that may involve jumps. AM bikes tend to have greater suspension then XC bikes and many include multiple positions for different rear shock lengths. AM frames are heavier due to thicker gauge tubing and/or frame gusseting. Typically these frames are designed to have 3 selectable front sprockets along with a 9 speed (cog) rear cassette allowing for a huge variation of pedal torque vs. gear inch travel.

Below is a typical bike build for AM frames that are oriented for this riding discipline:

Frame Design: Typically Full Suspension.
Frame Geometry: Head Tube Angle 68 degree; Seat Tube Angle 73 degree; Wheelbase 45 inches.
Average Build Weight: 28 to 35lbs depending on component selection.
Suspension Travel: 4 to 6 inches for both fork and rear shock.
Suspension Type: Air fork and rear shock. Coil suspension is optional.
Wheel Setup (Front): All-purpose rim with 32 hole QR hub.
Wheel Setup (Rear): All-purpose rim with 32 hole 10mm bolt-on hub.
Tire Size Range: 2.25 - 2.5 with a durometer of 65 (average).
Brakes: Hydraulic brakes with 6 & 8 inch disk rotors (front & rear or combination of both).
Crank Arms: 175mm.
Chainring: Three sprocket setup ranging from 22t - 46t.
Rear Cog Set: 9 speed cassette ranging from 12t - 34t.
Stem Length: 50mm - 90mm; 6 degree rise (average).
Handle bars: 24" - 26" width; 0" to 1.5" rise; 5 degree rearward & 4 degree upward sweep (average).

Freeride (FR): Mountain bikes that fall into this discipline are designed to handle the stress of large jumps and extreme technical riding. FR mountain bikes are probably the most versatile bike for aggressive technical riding. With today's suspension technology and rear linkage designs, FR bikes are somewhat capable of being ridden uphill and are moderately maneuverable at low speed regardless of a "slack" riding position. FR bikes typically run just one sprocket in the front with a 9 speed cog set in the rear. This is to reduce the overall length of the chain which will reduce the possibility of chain slap and miss-shifting during travel of the rear wheel.

Below is a typical bike build for FR frames that are oriented for this riding discipline:

Frame Design: Typically Full Suspension.
Frame Geometry: Head Tube Angle 66 degree; Seat Tube Angle 71 degree; Wheelbase 45.5 inches.
Average Build Weight: 32 to 45lbs depending on component selection.
Suspension Travel: 6+ inches for both fork and rear shock.
Suspension Type: Air fork and rear shock. Coil suspension is optional.
Wheel Setup (Front): Heavy-Duty rim with 36 hole 20mm hub.
Wheel Setup (Rear): Heavy-Duty rim with 36 hole 10mm bolt-on hub.
Tire Size Range: 2.5 - 2.7 with a durometer of 60 (average).
Brakes: Hydraulic brakes with 8 inch disk rotors (front & rear).
Crank Arms: 170mm.
Chainring: Single sprocket setup ranging from 32t - 46t.
Rear Cog Set: 9 speed cassette ranging from 12t - 34t.
Stem Length: 30mm - 70mm; 10 degree rise (average).
Handle bars: 24" - 27" width; 1.5" to 2.5" rise; 9 degree rearward & 4 degree upward sweep (average).

Slopestyle Bikes fall in-between AM & DH disciplines and do vary between bikes, most being used as an all purpose MTB (XC/AM/FR/DH), but these bikes can also be used in some competition as well.

Downhill (DH): Mountain bikes that fall into this discipline are designed for handling extreme technical riding at high speed. Typically with 8 inches of travel, DH bikes can handle the biggest jumps, steepest descents and most technical rock gardens that you have the balls for. Designed with a long wheelbase and "slack" rider position, a DH bike is not ideal for riding general trails in the woods, but will serve its purpose when you transverse trails on an exclusively lift accessed terrain. DH bikes as well as their FR bike cousins typically run just one sprocket in the front with a 9 speed cog set in the rear. This is to reduce the overall length of the chain which will reduce the possibility of chain slap and miss-shifting during travel of the rear wheel.

Below is a typical bike build for DH frames that are oriented for this riding discipline:

Frame Design: Typically Full Suspension.
Frame Geometry: Head Tube Angle 64 degree; Seat Tube, Angle 65 degree; Wheelbase 47 inches.
Average Build Weight: 38 to 60lbs depending on component selection.
Suspension Travel: 6 - 8+ inches for both fork and rear shock.
Suspension Type: Coil/oil fork and rear shock. Air is optional.
Wheel Setup (Front): DH rim with 36 hole 20mm hub.
Wheel Setup (Rear): DH rim with 36 hole 10mm bolt-on hub.
Tire Size Range: DH2.3 - 3.0 with a durometer of 50 (average).
Brakes: Hydraulic brakes with 8 inch disk rotors (front & rear). Higher end having double pads.
Crank Arms: 170mm.
Chainring: Single sprocket setup ranging from 32t - 48t.
Rear Cog Set: 9 speed cassette ranging from 12t - 34t.
Stem Length: 30mm - 70mm; 10 degree rise (average).
Handle bars: 26" - 28" width; 1.5" to 2.5" rise; 9 degree
rearward & 4 degree upward

I will make this statement in reference to DH specific bikes which are designed and built specifically for DH competition & racing. These are not toys but specially designed moto-cross grade MTB's that are heavier than XC & Trail MTB's that are designed to take a beating and reach speeds exceeding 40 mph. The world speed record for a DH specific MTB is over 130mph, and was done on snow.
ChiliPepper
 

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