Bike Flat Bars Explain + 6 Buying Tips for 2025

Most fixed gear riders choose flat bars for the wrong reasons—or confuse them with riser bars entirely. That aggressive track bike aesthetic 🚴 looks cool, but only if you actually get true flat bars with 0mm rise.

Flat bars (0mm rise) are aggressive speed machines 💪 with forward positioning, superior aerodynamics, and maximum power transfer. But comfort versus pain comes down to three things: understanding that flat means 0mm rise, matching bar width to your shoulders, and selecting proper sweep angles.

1. What Makes a Bar “Flat”? Understanding 0mm Rise

Critical definition: True flat bars have 0mm rise. This means the handlebar grips sit at the exact same height as the stem clamp—completely horizontal with no upward angle whatsoever.

Flat bars vs. Riser bars – These are COMPLETELY DIFFERENT:

• Flat bars: 0mm rise → Aggressive, forward-leaning position ideal for track bikes and fast urban riding where speed matters
• Riser bars: 10-40mm+ rise → More upright, comfortable position for casual riding and technical terrain

If you see bars advertised as “10mm rise” or “25mm rise” – those are riser bars, not flat bars. This article covers ONLY true flat bars (0mm rise) for aggressive fixed gear riding.

True flat bars create the most aerodynamic position possible with straight handlebars, putting your torso low and forward. This maximizes power transfer and speed but requires good core strength and flexibility. If you find yourself hunching or experiencing back pain after 30 minutes, you need either a shorter stem, more spacers, or riser bars instead.

2. Bar Width: The Make-or-Break Measurement

Bar width fundamentally determines control, breathing, and shoulder health. For fixed gear urban riding with flat bars, 520-620mm typically represents the practical range—wide enough for confident control without clipping car mirrors or doorways.

This is narrower than mountain bike flat bars (which run 720-800mm) because:

• Urban environments require navigating tight spaces
• The aggressive position of flat bars doesn’t need as much leverage as technical MTB riding
• Narrower bars improve aerodynamics for speed-focused riding

The standard recommendation: start 2-4cm wider than your shoulder width measured acromion to acromion (those bony protrusions where collarbones meet shoulders).

A more practical test? Measure your hand spacing during a pushup at your strongest position—this reveals your natural power stance and often matches ideal bar width better than static measurements.

Modern bars feature graduated markings every 5-10mm, allowing you to test narrower widths by sliding controls inboard before permanently cutting. Always start wide and trim gradually—you can’t add width back after cutting.

3. Sweep Angles: The Detail Most Riders Ignore

Backsweep (viewed from above) on true flat bars typically ranges 5-11°, with 6-8° being most common. This angle should match the natural sweep of your arms when extended to riding position.

Insufficient backsweep can force wrists into uncomfortable extension, causing ulnar nerve compression—that numbness in your pinky and ring fingers. Too much backsweep (over 11°) starts to feel awkward in the aggressive flat bar position.

Upsweep (viewed from side) on true flat bars is typically 0-2° – minimal or none. Many pure flat bars have 0° upsweep to maintain the aggressive, aerodynamic position. Anything over 4° upsweep starts turning a “flat” bar into a low-riser bar.

Common flat bar sweep configurations:

• Origin8 Pro Pulsion: 6° backsweep, 0° upsweep – traditional balanced flat bar
• Surly Cheater Bar: 11° backsweep, 0° upsweep – maximum comfort while staying flat
• Salsa Salt Flat: 11° backsweep, 6° upsweep, 0mm rise – technically still “flat” but the upsweep adds comfort

4. Clamp Diameter: Compatibility You Can’t Ignore

The 31.8mm “oversized” standard dominates modern bikes, offering massive component selection and superior stiffness. The older 25.4mm (1-inch) standard provides more compliance but limits component choices—fewer manufacturers produce quality 25.4mm bars today.

These sizes are NOT interchangeable without shims (which add weight and reduce stiffness). Before buying bars, verify your stem clamp diameter with calipers—don’t assume based on bike age.

5. Material Choices: Aluminum, Carbon, or Steel

Aluminum alloy dominates flat bar construction—specifically 6061-T6 for mid-range bars and 7050/7075 for premium options. A double-butted 6061 bar in typical fixed gear widths (520-640mm) weighs 175-340g and costs $29-60, representing the standard recommendation for most riders.

Double-butted construction means thicker walls at both ends (where stress concentrates) and thinner walls in the center, saving 20-30% weight versus single-wall bars while maintaining strength.

Premium 7050/7075 alloys offer higher tensile strength, allowing thinner walls—typically 150-280g for similar dimensions but often costing 1.5-2x more ($60-120 vs $29-60) for modest 30-60g weight savings.

Carbon provides superior vibration damping while reducing weight. This performance costs dearly: entry carbon starts at $145-180, mid-range runs $180-250, premium reaches $300-400+.

Carbon fails catastrophically without warning when damaged, requiring meticulous inspection after crashes and proper torque specs (typically 4-5Nm vs 5-6Nm for aluminum).

Steel chromoly bars offer exceptional durability and compliance. The Surly Cheater Bar weighs 400g in 780mm width but can be trimmed to 600-650mm for urban use. Steel bars are heavier than aluminum but provide superior vibration damping and legendary toughness—they bend before they break.

6. Installation Setup That Prevents Chronic Pain

Apply appropriate lubricant based on materials: medium-strength threadlocker or light grease for aluminum-on-aluminum interfaces, carbon assembly compound (Park Tool SAC-2 or similar) for carbon bars. Never use standard grease on carbon—it reduces friction too much, requiring over-tightening that risks cracking.

Install the new bar centered in the stem with controls removed initially. Partially tighten stem bolts, then stand over the bike and rotate bars to optimal angle. With flat bars (0mm rise), you’ll typically rotate them slightly forward to get wrists aligned naturally with forearms when gripping bars.

Tighten stem bolts in X-pattern to proper torque: typically 5Nm for stems, though always check manufacturer markings.

Brake lever positioning requires precision. Most modern brake systems operate with one or two fingers, so levers should be positioned inboard from traditional locations—aim for best leverage with just your index finger.

Lever angle should approximate 4 o’clock position (viewed from drive side), NOT parallel to ground despite this being trendy.

Testing bar width before cutting prevents irreversible mistakes. Slide grips and controls inboard to simulate narrower width. Calculate: (Current width – Target width) ÷ 2 = Distance to move each side inboard. Ride this setup for 15+ hours across various conditions before committing to cuts.

Three Flat Bars I Recommend

Final Thoughts

True flat bars (0mm rise) excel when matched to appropriate use cases and sized correctly for individual riders.

They transform fixed gear bikes into aerodynamic speed machines with aggressive positioning and maximum power transfer—but only when you understand that flat means 0mm rise, get width right, and select proper sweep angles.

Don’t overthink materials: double-butted aluminum delivers 95% of the performance at 40% of carbon’s cost. If you need the aggressive positioning and aerodynamics of flat bars, the Origin8 Pro Pulsion ($29) gets you started right.

When ready to upgrade, the Surly Cheater Bar ($80-104) provides bombproof steel durability. Only go carbon if you’re chasing every gram or need maximum vibration damping.

Your bar choice matters less than getting the fit right—a perfectly-sized budget bar outperforms expensive bars that don’t match your body. And remember: if you want an upright position, you don’t want flat bars—you want riser bars.