BMX bikes and mountain bikes may look similar at first glance, but they are designed for very different riding styles and terrains. BMX bikes are made for extreme tricks and jumps in skateparks or on the streets, while mountain bikes are specifically engineered for climbing steep, uneven trails and conquering a variety of off-road terrain.
So can you use a BMX bike for mountain biking? While it is possible to take a BMX bike onto mountain biking trails, it is not recommended for serious mountain biking. BMX bikes lack the durability, gearing, and components that make mountain bikes suitable for rugged wilderness rides. Riders who attempt intense mountain biking on a BMX bike are likely to find themselves walking or carrying their bikes frequently when trails become too steep or technical.
However, casual mountain biking on easier, smoother trails may be possible with a BMX bike. The limitations lie in their lack of suspension, smaller knobby tires, and single-gear drivetrains. Understanding the critical differences in frame geometry, components, and intended use can help determine if an adapted BMX bike could work for mellower mountain trail riding.
Crucial Differences Between BMX and Mountain Bikes
While BMX and mountain bikes share some similar traits like handlebars, saddle, and wheels, they diverge in some important ways that affect their performance and handling for different riding environments.
- BMX bikes have compact frames with shorter wheelbases and tighter headtube angles for quick, responsive handling, ideal for tricks and stunts.
- Mountain bike frames are longer with slacker headtube angles for stability and comfort over rough terrain. The lengthened wheelbase improves handling at high speeds.
- BMX bikes lack any suspension elements. Rigid frames transfer impact directly to the rider but are efficient for pumping and jumping.
- Mountain bikes have suspension forks in the front and sometimes full suspension frames to absorb impact for improved control and a smoother ride over rocks and roots.
Gears and Drivetrain
- BMX bikes have a single gear with no shifters. Their drivetrain is simple and low maintenance.
- Mountain bikes have a wide range of gears (often 27 or more) controlled by shifters. Multiple chainrings and larger cassettes help manage changing inclines.
Wheel and Tires
- BMX wheels are 20”, with slick or lightly treaded tires designed for pavement or dirt jump tracks.
- Mountain bike wheels are typically 26”, 27.5”, or 29” to roll over obstacles better. Knobby mountain bike tires grip loose terrain.
- BMX parts like cranks, pedals, and handlebars are designed for strength to withstand hard landings. Minimal gearing reduces weight.
- Mountain bike components aim for versatility and reliability across changing conditions. Beefed up suspension forks and dropper seat posts enhance technical handling.
The Viability of Using a BMX for Mountain Biking
The stark differences in frame design and components mean most serious mountain biking trails will prove too challenging for the average BMX bike. However, modified BMX bikes may stand up to smoother, flowing singletrack under the right conditions.
- Playful handling – Quick steering suits pumping rollers and dirt berms.
- Simple to operate and maintain – No shifting or suspension to worry about.
- Durable construction – Strong frames and parts hold up to jumps and crashes.
- Light weight – Easier to manuever up short pitches than a heavy dual suspension MTB.
- Lack of gearing – Spinning out is likely on descents, while steep climbs may require walking.
- Smaller wheel size – Harder to roll over larger roots, rocks and holes. Less stable at high speeds downhill.
- Minimal tire tread – Prone to washouts in loose or muddy conditions.
- No suspension – Frame absorbs all shock and vibration, tiring on long rides.
- Seating position designed for bursts of power rather than sustained pedaling.
Tips for Attempting Mountain Biking on a BMX Bike
Riders set on using a BMX bike for casual mountain biking should consider the following tips to improve the bike’s capabilities and pick appropriate terrain:
- Swap tires for wider, grippier mountain bike treads with knobby cornering knobs. Wider tires provide more cushioning and control.
- Add platform pedals for sturdier footing when pedaling over obstacles. Avoid thin, skate-style pedals.
- Use higher tire pressure – 45-65 psi compared to 20-40 psi for street riding. This prevents pinch flats at low speeds.
- Stick to blue square and green circle-rated trails free of large drops or jumps. Focus on smooth singletrack and dirt roads over technical rock gardens.
- Ride conservatively – No big jumps or high speeds. Practice controlled braking bumps before corners. Stay light in the saddle and ready to stand when needed.
- Climb carefully in easier gears, leaning forward to keep the front wheel grounded. Walk the bike if the grade steepens.
- Descend with caution – Use both brakes to control speed and remain centered over the bike.
- Maintain momentum to clear small obstacles like roots rather than charging them.
- Check bolts frequently as the rigid frame experiences more vibration. Carry tools to make adjustments on the trail.
With preparation and prudent ride planning, BMX bikes can handle mellow off-road terrain for short distances. But steep, loose, or highly technical trails are best left to purpose-built mountain bikes.
The Bottom Line: Expect Limitations Without Proper Gear
In summary, while it is possible to ride mild mountain biking trails on a BMX bike, steep or technical terrain will prove extremely challenging without proper mountain bike gearing, suspension, and tires.
Serious mountain biking requires a purpose-built mountain bike to enjoy the full range of trails. But riders hoping to occasionally branch onto smoother singletrack may be able to adapt their BMX bikes with some modifications for limited off-road use.
Focusing on easy terrain, maintaining momentum, and improving technical handling skills can all help maximize the experience. However, understanding the BMX’s limitations in traction, control, and power output is important for a fun and successful ride.
- BMX bikes lack the suspension, drivetrain, and tires that make mountain bikes capable on rugged terrain.
- Attempting to use a BMX bike for mountain biking is only recommended for easier, smoother trails.
- Upgrading to wider mountain bike tires vastly improves traction and control.
- Riding conservatively and maintaining momentum helps overcome gearing and wheelsize limitations.
- Heavily modified BMX bikes blur the line between BMX and entry-level mountain bikes.
What size of mountain bike tires can fit on a BMX?
With some frame modifications, BMX bikes can typically fit mountain bike tires up to about 2.30-2.50″ wide. Any wider rubbing on the frame or fork will become an issue.
How do I convert my BMX gearing for trails?
Swapping the rear wheel for a simple single speed freewheel rather than a cassette lets you coast instead of always pedaling. A larger 36T-44T chainring up front helps gain more speed.
Can I put full suspension on a BMX?
It’s possible but very uncommon. The smaller 20″ wheels and compact frames limit suspension travel, while the cost is usually prohibitive. Front suspension forks are much more popular and effective upgrades.
What are the best tires for mountain biking on a BMX?
Look for wider mountain bike tires in the 2.0-2.5” range with aggressive side knobs for cornering traction. Brands like Maxxis DTH or Kenda Nevegal are good options.
So, in summary, converting a BMX for occasional mellow trail riding is possible with the right modifications and cautious riding style. But for regular mountain biking, a purpose-built mountain bike is a far better investment for safety, capability and enjoyment on rugged backcountry trails.
Mahin Abrar is a passionate writer and outdoor enthusiast. As a regular contributor to Bikepics.net, Mahin shares his knowledge and experiences in the fields of biking, cycling, hiking, and camping. With a deep understanding of these activities and a keen eye for detail, he offers valuable insights and practical advice to help readers get the most out of their adventures. Whether you're a seasoned pro or just starting out, Mahin's writing is sure to inspire you and guide you on your journey.