Ultimate Lightweight Drop-Bar MTB: Perfect for Bikepacking & Adventure

The allure of the drop bar mountain bike lies in its unique ability to combine the rugged durability of a mountain bike with the aerodynamic and ergonomic benefits of drop bars. As someone who loves tackling mixed-terrain routes and endurance events, the idea of building a drop bar MTB felt like the perfect way to bridge the gap between performance and versatility.

Drop Bar MTB vs. Gravel Bike

While gravel bikes are great for mixed-terrain riding, drop bar MTBs take it a step further by offering enhanced control and durability for more technical off-road conditions. The key difference lies in geometry and component design: drop bar MTBs have slacker head angles, longer wheelbases, and sturdier frames that allow for better stability and handling on rough trails. They also feature wider tire clearance for larger, more durable tires and are built to withstand the abuse of technical descents and challenging terrain.

In contrast, gravel bikes are designed for speed and efficiency on smoother dirt roads and light trails, with a focus on comfort and versatility.

Bike Build & Specs

At the heart of this build is my goal for lightweight performance. To achieve this, I turned to the German brand Bike Ahead Composites, known for producing high-quality components in Europe that strike the perfect balance of weight, strength, and durability.

Key Components:

• The Frame: Bike Ahead Composites Hardtail

• Biturbo RSX Wheelset

• The Racebar

• The Straight Seatpost

• Rockshox Sid SL Ultimate 3 Suspension Fork

• SRAM XX Eagle Transmission

• SRAM Force E-Tap AXS Levers

• Kogel Ceremic Bottom Bracket & Cage

• Continetal Race King 2.2 Tyres

  
  

THE FRAME: Bike Ahead Composites

THE FRAME Weight (Size S): 775 Grams Price: €1.978,99

1. Frame Geometry for Control and Comfort:

   
   
   
   

   

   
   
   
   

   • Slacker Head Angle: Paired with a shorter 50mm stem, it offers greater stability and confidence on steep descents.

   • Higher Bottom Bracket: Provides crucial clearance over rocks and technical obstacles.

   • Extended Wheelbase: My chosen frame is 6.2cm longer than my gravel bike, enhancing stability at speed.

     
     

   The geometry is designed to handle a wider range of terrains, from technical singletrack to fast dirt roads, making it ideal for the varied demands of the races I have planned.

   
   

2. Decent Triangle for Self-Supported Racing:

   One advantage of The Frame in comparison to other Hardtail frames is its bigger sized triangle, which accommodates a standard 2l Apidura frame bag and one bottle cage. This added storage capacity is critical for self-supported events like the Atlas Mountain Race, allowing me to carry more gear and hydration without sacrificing balance or handling.

   
   

3. Tire Clearance for Traction and Comfort:

   The Frame easily fits 2.2-inch tires, giving me the ability to run Continental Race Kings. These tires combine top rolling efficiency with the volume needed to handle rough terrain and absorb trail vibrations. This extra clearance also ensures mud doesn’t clog up the frame, a common issue on gravel bikes with narrower clearance.

   
   

4. Lightweight Durability:

   Weight plays a significant role in off-road endurance events. Every gram saved means less energy expended over long climbs and technical trails. The Bike Ahead Composites frame, at under 800g, delivers MTB-level durability at a weight comparable to high-end gravel bikes. The Frame is not only one of the lightest on the market but also competitively priced compared to other high-end frames in the same weight category.

   
   

Drop Bars: The Best of Both Worlds?

The drop bar itself is a key reason I pursued this build. While flat bars are great for technical riding, they can cause discomfort on long days in the saddle due to limited hand positions.

Drop bars: THE RACEBAR  Weight (42mm): 210 Grams

• Provide multiple positions: Alleviating hand and wrist fatigue on long rides but most importantly allowing me to replicate my usual position without the need to adapt.

• Improve aerodynamics: Crucial for faster stretches or battling headwinds in open areas.

  
  

  For this build, I mounted SRAM Force eTap AXS shifters on the drop bars, which are compatible with the SRAM Eagle XX MTB groupset. This wireless 1x12-speed drivetrain features a 10-52 cassette, providing a wide range of gears ideal for both technical and endurance riding. The key advantage of this system is its ability to shift under load, ensuring smooth gear changes even during tough climbs or when pushing hard. It’s also mounted directly to the frame, reducing the risk of bending the derailleur hanger, an issue I’ve encountered with gravel bikes during races more times than not. The setup gives me the best of both worlds: comfort and performance.

  The topic of drop bars on MTBs is a bit controversial with purists advocating against it due to better handling of flatbars, unusual looks and the supposed irrelavance of aerodynamics for off-road ultras. I personally come from road-cycling and simply prefer the hand positions on dropbars and the optionality to get lower with the back on flat stretches.

  The handling advantages of the flatbars are not as relevant for me as I ride technical sections with a loaded bike very conservatively and consider myself a beginner cyclist off-road and therefore ride steep downhills far slower than the limit of the bike. The built is designed as an alternative to a gravel bike just with bigger, faster tyres and suspension rather than a trail bike to race MTB races competitively.

Why Six-Spoke Wheels?

The six-spoke wheels from Bike Ahead Composites were an integral part of the build, chosen for their weight & reliability and my positive experience with them on my road-bike.

1. Built for Rough Terrain

   • With an ASTM 3 rating, these wheels can handle impacts from drops up to 60cm, far beyond what gravel-specific wheels are designed for. I get a lot of comments and messages that six-spoke wheels are not robust enough for off-road use, I would suggest checking out and comparing the ASTM ratings of different, typical spoked-wheelsets.

   • They’re optimized for tubeless MTB tires, with a 33mm inner rim width so perfect to work with my preferred Conti Race Kings.

     
     

2. Incredibly Lightweight

   • At just 1,329g, the wheels are exceptionally lightweight for their category, reducing overall bike weight and improving efficiency on climbs and long-distance rides.

     
     

3. Reliability for Self-Supported Racing

   • The unique design eliminates spokes and spoke-holes, meaning no risk of sealant leaking, incredibly little pressure loss over days or broken spokes.

   • Tubeless setup is simplified, with no need for rim tape.

Other Key Components

Suspension:

The RockShox SID Ultimate SL is one of the lightest suspension forks available, offering 100mm of travel. This suspension is crucial for smoothing out technical sections, providing more comfort and a forgiving ride on rough terrain. Given that I’m still building my off-road skills, having this margin of error is essential. The ability to absorb bumps and drops ensures better control, reduces fatigue, and boosts confidence. This is another reason why I opted for an MTB setup, as gravel bikes don’t offer the same level of suspension travel, limiting their performance on more demanding off-road trails.

With races like Atlas Mountain Race on the agenda I felt that I needed at least 100mm of suspension travel as well as 2.2 inch tyres.

Braking System: The 180mm rotors provide exceptional stopping power, even on steep descents. For ultra-endurance races, the ability to brake effectively without overloading my hands is crucial. Larger rotors offer more braking leverage, reducing hand fatigue and ensuring that I can safely navigate downhill sections without compromising my overall ride comfort.

Seatpost: I opted for the Lightweight Straight Seatpost from Bike Ahead Composites, weighing just 160 grams. While a dropper post can be useful in certain technical descents, I decided it wasn't necessary for this race due to the course profile and the fact that I rather walk very steep sections than sending them.

Additionally, the flexibility to install a dropper post in the future if needed provides versatility as my riding style hopefully evolves.

Bottom Bracket: To ensure smooth pedaling performance and durability, I’ve included a Kogel Ceramic Bottom Bracket with Endurance Seals. The ceramic bearings reduce friction and enhance overall drivetrain efficiency, while the seals help keep everything running smoothly over long distances and in varied conditions. This is especially important for longer races where performance and reliability are paramount.

Derailleur Cage: Adding a touch of color and performance, I’ve installed a Kogel Kolossos Oversized Derailleur Cage. This not only improves shifting performance due to the stiffer cage and reduces chain drag but also adds a bit of flair to the bike's overall aesthetic.

Drop Bar MTB Setup vs. Gravel Bike: Pros and Cons

Feature	Drop Bar MTB Setup	Gravel Bike Setup
Weight	8.6 kg (with 100mm suspension fork)	9.5 kg (with 20mm suspension stem)
Transmission	SRAM 1x with more gears, shifts under load, more MTB-specific gear range, limited to 38t front	Mullet setup with SRAM Eagle MTB groupset, similar gear range, bigger front chainring
Wheelset	MTB wheels (lightweight, durable, better for rough terrain, ASTM 3 rating)	Gravel wheels (not as durable for rough terrain, lower ASTM rating)
Tire Clearance	More clearance for wider MTB tires (faster rolling, better puncture resistance)	Limited clearance for MTB tires, narrower tires that are less puncture-resistant
Suspension	100mm RockShox fork (better for rough trails and technical sections)	20mm suspension stem (less travel, limits comfort on rough terrain)
Braking Power	180mm rotors (stronger, more reliable braking)	Standard gravel bike brakes (less powerful on steep descents)
Durability	More durable for extreme off-road conditions (MTB frame, components)	Less durable for rough terrain (designed more for gravel, not extreme MTB use)
Flexibility	Can mount a dropper post in future for more technical descents	Can mount a dropper post in future for more technical descents
Price	Competitive pricing for high-end MTB frame and components	Higher cost for gravel bike frames with similar performance capabilities
Ride Feel	More forgiving and comfortable on rough terrain, smoother in technical sections due to 100mm suspension	Less comfortable on technical terrain, less stability on rougher trails, faster on light gravel, more snappy, accelerates faster
Terrain	Designed for a wide range of terrains from rough singletrack to long gravel roads, handles more technical terrain with ease	Best suited for gravel roads, mixed terrain and less capable on rough or highly technical trails without suspension

Things to Consider When Building a Drop Bar Mountain Bike

1. Group Set Compatibility: Opt for SRAM AXS wireless for easy setup and compatibility with drop bar bikes.

2. Transmission Standards: Pay attention to bottom bracket and chainline for efficient 1x drivetrain setup.

3. Reach Adjustment: Expect a longer reach when switching to drop bars; adjust frame and stem accordingly.

4. Remote Mounting for Suspension: Ensure remote is accessible; drop bars may need adapters for mounting. Remote does not mount on standard dropbars, DIY solution needed (or mount it on standard aerobars)

5. Brake Rotor and Caliper Compatibility: Check brake rotor (typically 180mm) and caliper compatibility with frame and wheels. Beware of post mount standard for the calipers and 6-bolt rotors for MTB wheels.

6. Compatibility of wheels, due to different axle-standards your gravel wheels don't fit the frame, you need MTB wheels.

7. Maximum chainring size: typical MTB frames only clear 36, sometimes 38t chainrings. Make sure this is sufficient for your type of riding before considering the switch.

8. Garmin-mounts: if you want to replicate your gravel position you will need a negative angle stem (-17 degrees or more), so get a Garmin mount with variable angle, the straight ones will point downwards otherwise.

9. Mounting options: I chose a very lightweight XC race frame without mounting bolts or compartments. Threrefore top-tube bag, frame bage etc. need to be mounted with straps, no pannier or fender mounts on the frame.

Ride Feel and Test

This bike is incredibly lightweight and compliant, making a huge difference on steep hills. The combination of its weight and gear ratio makes climbing an absolute bliss. The ability to shift under load with the SRAM transmission system is a game changer compared to my gravel bike.

It also feels very reliable and stable on descents. Thanks to the suspension, it handles technical terrain better while offering multiple hand positions with the drop bars. Braking is noticeably easier too, thanks to the larger rotors, which reduce hand fatigue a common issue for me in ultra races.

While it’s not as fast on tarmac, the drop bars allow for a lower, more aerodynamic position compared to a flat bar, though I am seated slightly higher than on my gravel bike. Average speeds on flatish gravel routes so far very, very similiar between the bikes. Need to do more testing in the mountains and on travels to give a more complete picture.

All in all, so far from the little testing I have done it feels like a close to perfect configuration for mixed terrain when most of my time is spent off-road or on trails. My gravel bike certainly edges out on light gravel and asphalt, but this setup shines everywhere else.

Stay tuned for a more detailed ride and experience report after Atlas Mountain Race!