Answer: If you’re upgrading a bicycle crank, look for a forged alloy construction, correct spindle interface, and the right length for your riding style. The following five crank arm sets are chosen for different rider needs—from lightweight, control-focused mountain biking to broad compatibility with common square- and diamond-hole interfaces. This guide helps you pick the best option for performance, durability, and fit. Ideal buyers include frequent trail riders, ebike and road cyclists needing reliable compatibility, and DIY enthusiasts restoring an older setup.
| Product | Crank Arm Length | Interface | Best For |
|---|---|---|---|
| BNVB Bike Crank Arm Set | 170mm | 104mm BCD, 74mm crank spread | All-around MTB riders seeking lightweight strength |
| Alps2Ocean Bike Crank Arms (Diamond Hole) | 170mm | Diamond Hole | EBikes and riders needing multiple size options |
| THALOUS Bicycle Crankset | 170mm | Square | Cross-compatibility with 3×8/7/6 speeds |
| Relwears Bike Crankset FC-TY301 | 170mm | Square | Versatile, reliable shifting with 3x setups |
| Epessa Crank Arm (Diamond/Square Hole) | 170mm | Diamond or Square | Flexible interface and universal fit |
BNVB Bike Crank Arm Set With Bottom Bracket Bolts
Materials and design emphasize lightweight strength. The BNVB set uses high-strength aluminum alloy, delivering a weight around 675 grams. Its ergonomic construction provides better control for aggressive trail riding or fast road climbs. The 170mm crank arms, 104mm BCD, and 74mm crank-related hole spacing match many common MTB and road configurations, simplifying compatibility with Shimano, FSA, and other brands. This option is best for riders who want a balanced mix of stiffness, low weight, and straightforward installation. Caution: verify that the bottom bracket width (68–73mm) matches your frame for proper chainline alignment.
Best for: riders who want a light, strong crank with broad compatibility and a straightforward install for MTB and cross-country riding. Better for: users who value a simple, durable upgrade over OEM hardware.
Alps2Ocean Diamond Hole Crank Arms (Multiple Sizes)
These forged Alloy 6061 crank arms offer ten available sizes, including 170mm and 175mm, with a focus on diamond hole (spindle interface). They’re designed for riders who want precise sizing to match their crankset and crankset-to-bottom-bracket geometry. The diamond hole interface ensures a consistent mating orientation for both sides. Best for ebike users and riders who need a wide range of sizes to dial in the ideal crank length. Limitation: confirm that both crank arms share the same hole orientation and that your spindle is the Diamond Hole type.
Best for: riders seeking extensive size options and a durable forged-aluminum build. Choose this if you ride a mix of terrains and want exact length compatibility. Avoid this if your bike uses a non-diamond hole interface or you’re unsure about hole orientation.
Alps2Ocean Diamond Hole Crank Arms (Second Size Range)
This listing mirrors the same durable 6061 forged alloy construction with ten sizing options, reinforcing its suitability for riders who want precise customization of crank length to match riding style and leg reach. Diamond Hole compatibility remains the focus, so ensure your crank orientation aligns. Best for: riders upgrading multiple bikes or building a custom setup where exact crank length matters. Caution: verify compatibility with your left-right crank pairing to avoid mismatched holes.
THALOUS 42/34/24T Universal Square Crankset
THALOUS offers a square crankset with 42/34/24 teeth, designed for 3×8, 3×7, and 3×6 drivetrains. The 170mm crank arm length pairs with 9/16″ pedals, and the forged aluminum alloy 6061-T6 construction emphasizes lightness and durability. This option suits riders who want reliable shifting performance across varied gears and a budget-friendly upgrade. Caution: square cranksets require correct spindle type and bottom bracket compatibility; confirm both before purchase.
Best for: riders upgrading legacy 3x drivetrains who need a robust, lightweight square-arm option. Choose this if you ride on mixed terrain and value precise, consistent shifting. Avoid this if your bike uses non-square interfaces or you need a single-speed style setup.
Relwears FC-TY301 42-34-24T 170MM Crank Arm
The Relwears FC-TY301 offers a 24-34-42T chainring configuration with 170mm crank arms, designed for 3×6/7/8 speed drivetrains and 9/16″ pedals. Aluminum alloy construction improves rigidity and reduces weight, supporting solid power transfer. This option is well-suited for riders who demand reliable, smooth shifting and broad compatibility with older triple-chainring setups. Caution: ensure the bottom bracket shell width and spindle interface match your frame and crankset.
Best for: riders upgrading to a safer, versatile triple-chainring system. Choose this if you need robust performance across diverse terrains. Avoid this if you require a newer 1x or a non-square taper interface.
Epessa Crank Arm Left In Diamond or Square Holes, 170mm
Epessa offers a versatile crank arm with both Diamond Hole and Square Hole options, 170mm total length. It fits 9/16″ pedals and is manufactured from high-quality aluminum alloy. This flexibility makes it suitable for riders who own bikes with different spindle interfaces or who want a single upgrade that accommodates multiple configurations. Limitation: confirm the correct spindle interface (Diamond vs Square) before ordering to ensure proper fitment.
Best for: riders needing interface flexibility or working with bikes that require a mixed-hole approach. Choose this if you might swap interfaces in the future. Avoid this if you require a dedicated single-interface crank arm for a dedicated build.
PATHGNAR Square Hole 170MM Crank Arm
PATHGNAR markets a 170mm, square-taper crank arm designed for electric bikes with mid-mounted motors. The forged Alloy 6061 construction emphasizes strength and hardness, supporting heavy use. The square taper interface requires matching orientation for both sides. Best for: riders upgrading OEM cranksets on mid-drive e-bikes where a durable, square-taper option is needed. Caution: this arm is marked for electric bikes; confirm your drivetrain is compatible with square taper and the motor’s torque profile.
Buying Guide
- Crank arm length: Common lengths are 170mm, with 165mm and 175mm also used. Choose based on leg length, riding style, and pedal position to maintain efficient pedaling.
- Interface type: Diamond Hole (also called Diamond or ISIS) and Square Taper are the two dominant interfaces. Ensure both crank and bottom bracket/spindle match and that the hole orientation is correct for the setup.
- Material and weight: Forged Aluminum 6061 offers a good balance of weight and strength. Heavier arms can add stiffness but may impact overall weight for performance-focused riders.
- Bottom bracket compatibility: Check shell width (e.g., 68–73mm is common) and ensure the crank fits your frame’s bottom bracket standard to maintain proper chainline.
- Gear compatibility: If you ride a 3x drivetrain, a 42-34-24T or similar triple chainring configuration may suit you. For 1x setups, consider single-ring options with appropriate chainline.
- Installation and maintenance: Look for crank arms that include hardware or bolts compatible with your bottom bracket. Some listings note included bolts; verify what’s in the box to avoid extra purchases.
FAQ
- What length crank should I buy?
The most common length is 170mm, but shorter or longer arms suit different leg lengths and riding styles. Consider your inseam and pedal efficiency when choosing. - What is Diamond Hole vs Square Taper?
These are two spindle interfaces. Diamond Hole is a four- or six-bolt pattern used by some square-taper styles; Square Taper is a traditional interface. Ensure your frame and crank match before purchasing. - Can I mix crank arms from different brands?
Mixing is possible if the interfaces and chainlines align. However, mismatches can cause shifting issues or mechanical interference. Verify compatibility with your bottom bracket and chainring setup. - Are lightweight crank arms weaker?
Lightweight forged aluminum arms typically balance weight with stiffness. If you ride aggressively or on rough terrain, look for arms with higher rigidity and proper torque tolerance. - Do crank arms include bolts and spacers?
Some listings include bolts and chainring bolts, while others require separate purchases. Check product details to confirm what’s included.