Mountain Bike

The primary riding discipline the mountain bike is designed for, which dictates frame geometry, suspension travel, and component selection.

Choose based on your primary riding style and terrain. Trail bikes are the most versatile starting point. If you spend over 70% of time descending technical terrain, consider enduro. For racing or fitness-focused riding, lean toward cross country.

Whether the bike has front suspension only (hardtail) or both front and rear suspension (full suspension), fundamentally affecting comfort, traction, and efficiency.

Full suspension is recommended for most trail riding with significant rocks, roots, and descents. Hardtails are ideal for smoother trails, racing on a budget, or riders who prefer a simpler, lighter machine. Modern full suspension designs minimize pedaling efficiency losses.

The nominal diameter of the wheel/rim, which affects rollover ability, acceleration, handling precision, and tire volume availability.

29" dominates XC and trail categories for rollover and speed. 27.5" suits smaller riders and playful riding styles. Mullet setups are increasingly popular in enduro for combining front stability with rear agility. Most modern frames are designed for one specific size.

The maximum distance the front suspension fork can compress, measured in millimeters. Determines the size of obstacles the bike can absorb and influences frame geometry.

Typical range: 80–200 mm

XC bikes typically use 100-120mm, trail bikes 130-150mm, enduro bikes 150-170mm, and downhill bikes 180-200mm. More travel provides better bump absorption and steep terrain capability but adds weight and can make the bike feel less responsive on smooth terrain.

The maximum distance the rear wheel can move vertically on full suspension bikes, measured in millimeters. Works in conjunction with front travel to absorb impacts.

Typical range: 80–210 mm

Rear travel is typically slightly less than front travel. XC full suspension: 100-120mm, trail: 120-140mm, enduro: 150-170mm, downhill: 180-210mm. Balanced front/rear travel provides consistent handling. Many frames allow travel adjustment via shock stroke changes.

The primary material used in the main triangle and frame construction, affecting weight, ride quality, durability, and cost.

Aluminum offers the best value for most riders and is the most common choice. Carbon is worth the premium for racers and weight-conscious riders who can afford it. Steel appeals to riders valuing ride feel and repairability. Titanium is a lifetime investment for discerning riders.

The total weight of the complete bicycle without pedals, measured in kilograms or pounds. Affects acceleration, climbing speed, and maneuverability.

Typical range: 9–18 kg

XC race bikes: 9-11kg, trail: 12-14kg, enduro: 13-15.5kg, downhill: 15-18kg. Weight matters most for climbing and acceleration. Rotating weight (wheels/tires) has a larger effect than static frame weight. Don't sacrifice reliability or capability for minimal weight savings.

The angle of the head tube relative to the ground, measured in degrees. A primary determinant of steering speed and high-speed stability. Slacker angles (lower numbers) provide more stability at speed.

Typical range: 62–71 degrees

XC bikes: 67-69°, trail: 65-67.5°, enduro: 63.5-65.5°, downhill: 62-64°. Slacker angles provide more stability on steep descents but make climbing steering feel less precise. Steeper angles offer quicker, more responsive steering. A half-degree change is noticeable.

The horizontal distance from the center of the bottom bracket to the top of the head tube, measured in millimeters. The most important sizing metric for modern mountain bikes as it determines the rider's fore-aft position while standing.

Typical range: 380–530 mm

Reach is the primary sizing metric for modern MTBs. Typical ranges: S (410-425mm), M (435-455mm), L (460-480mm), XL (485-510mm). Longer reach provides more stability at speed and room to move on the bike. Size up for stability, size down for agility. Personal preference and riding style matter significantly.

The vertical distance from the center of the bottom bracket to the top of the head tube, measured in millimeters. Determines how tall the front end feels and affects rider position between seated and standing.

Typical range: 560–680 mm

Higher stack provides a more upright, comfortable position and easier front wheel lifting. Lower stack enables a more aggressive, aerodynamic position. Stack-to-reach ratio around 1.4-1.5 is typical for trail bikes. Riders with less flexibility may prefer higher stack values.

The distance from the center of the bottom bracket to the center of the rear axle, measured in millimeters. Affects how easily the bike manuals, wheelies, and navigates tight turns.

Typical range: 415–460 mm

Shorter chainstays (415-435mm) make the bike more playful and easier to manual/wheelie. Longer chainstays (440-460mm) provide more stability at speed and better climbing traction. Trail bikes typically run 430-445mm. Some modern bikes feature size-specific chainstay lengths.

The angle of the seat tube relative to the ground, measured in degrees at saddle height. Affects climbing position and pedaling efficiency. Steeper angles position the rider more directly over the bottom bracket.

Typical range: 73–80 degrees

Modern mountain bikes feature steeper seat tube angles (75-78°) for better climbing position. Steeper angles (76°+) keep weight forward on steep climbs. Effective angle changes with seat height—taller riders may experience slacker effective angles on some frames. Look for 'effective at saddle height' measurements.

The number of rear sprockets in the cassette, which determines the number of gear ratios available and the size range of the cassette.

12-speed is the current standard and recommended for new purchases. 1x drivetrains (single front chainring) are universal in modern mountain bikes, simplifying shifting and reducing dropped chains. Budget for at least 11-speed if buying used.

The type of braking system, specifically the actuation method and rotor standard, which determines stopping power, modulation, and maintenance requirements.

Hydraulic disc brakes are strongly recommended for all mountain biking. 4-piston calipers are preferred for trail, enduro, and downhill. 2-piston is adequate for XC and light trail. Mechanical disc brakes should only be considered for very budget-constrained purchases.

The diameter of the brake rotors in millimeters. Larger rotors provide more stopping power and better heat dissipation, critical for sustained descents.

Front/rear rotor sizes often differ (e.g., 180mm front, 160mm rear). For trail riding, 180mm front is the minimum recommended. Enduro riders typically run 200mm front / 180mm rear. Upsizing rotors is one of the most cost-effective braking upgrades.

The nominal width of the tires mounted on the bike, measured in inches. Affects traction, rolling resistance, bump absorption, and frame clearance requirements.

Typical range: 1.9–5 inches

XC: 2.0-2.3", trail: 2.3-2.5", enduro: 2.4-2.6", plus/fat: 2.8-5.0". Wider tires provide more traction and bump absorption but increase weight and rolling resistance. Front tire is often run slightly wider than rear for cornering grip. Check frame clearance before upsizing.

The maximum distance the dropper seatpost can drop the saddle, measured in millimeters. More travel allows the saddle to get further out of the way for descending.

Typical range: 60–230 mm

Get the maximum travel that fits your frame and allows full leg extension at the top. Common sizes: 100-125mm (S/M frames), 150-170mm (M/L frames), 175-210mm (L/XL frames). More travel is almost always better for descending. Measure seat tube length and insertion depth before purchasing.