ethirteen Helix Core espec Cranks for ISIS Spindle - 155mm, 26mm Offset, Black

e*thirteen Helix Core e*spec Cranks for ISIS Spindle Motor Systems - 155mm, 26mm Offset, Black

The e*thirteen Helix Core e*spec Cranks deliver an exceptional e-bike drivetrain upgrade, combining high-end structural integrity and refined aesthetics at an extreme value. Engineered to withstand the relentless torque and punishing loads of modern e-MTB riding, these cranks ensure you never have to hold back on your next gravity run. By blending a value-conscious production layout with robust construction, e*thirteen provides privateers and daily trail riders with a reliable alternative to premium-priced models without sacrificing trail confidence.

This model is engineered for standard 24mm ISIS spindle motor interfaces, offering seamless compatibility with the market's leading e-bike platforms—specifically optimizing layouts for the Bosch CX Gen 4/Gen 5, Bosch SX, TQ HPR50, Brose S Mag, DJI Avinox, Yamaha, and Specialized 2.2/3.1 motor systems. Featuring a wider 26mm offset (measured at 26.5mm offset geometry), these cranks are ideal for frames requiring maximum clearance around wide chainstays and chunky rear suspension pivots. This offset achieves a stable, highly balanced stance width with generous Q-factors depending on your motor: a precise 181mm on TQ platforms, 184mm on Bosch Gen 4 systems, and 197mm on Brose setups.

At an ultra-short 155mm length, these crank arms are an eMTB-preferred solution specifically tailored to solve the problem of pedal strikes on modern, low bottom-bracket frame geometries. Shorter crank lengths allow you to spin smoothly through tech-heavy, rock-strewn climbs with a fluid cadence, drastically reducing the risk of catching a pedal while maximizing your motor’s power output. For ease of maintenance, the arms feature an integrated alloy self-extracting crank bolt system that makes routine home workshop servicing and installation quick, simple, and efficient.

Weighing a light 481g, these stealthy black crank arms are forged from high-strength AL 6066-T6 aluminum to ensure maximum durability against heavy rock strikes and accidental casing. e*thirteen packs this economic upgrade with premium attention to detail, including durable steel pedal washers to protect the spindle threads from high-load deformation and custom-molded composite crank boots that act as a resilient shield against trail debris. Fully engineered for aggressive trail duty, the Helix Core e*spec cranks are backed by e*thirteen's dependable 5-year manufacturer warranty.

Key Features

• Forged AL 6066-T6 Aluminum Construction: Delivers high-end durability, structural stiffness, and dependable trail strength at an accessible price point


• Ultra-Short 155mm Length: Maximizes ground clearance on low-slung e-MTB geometries to prevent pedal strikes on technical singletrack


• Generous 26mm Wide Offset Profile: Provides ample clearance for wide chainstays and suspension pivots, yielding a stable and comfortable trail stance


• Standard 24mm ISIS Compatibility: Designed for flawless integration with Bosch CX, Bosch SX, TQ HPR50, Brose S Mag, DJI Avinox, Yamaha, and Specialized systems


• Integrated Alloy Self-Extractor: Heavy-duty self-extracting bolt configuration makes installation and routine drivetrain maintenance efficient and tool-free


• High-End Hardware Inclusions: Comes equipped with durable steel pedal washers and high-impact molded protective crank boots for maximum longevity

Specifications

• Model: e*thirteen Helix Core e*spec Cranks


• Crank Arm Length: 155mm


• Spindle Interface Type: 24mm ISIS Spindle


• Crank Offset: 26mm (26.5mm architecture)


• Realized Q-Factors: TQ: 181mm | Bosch G4: 184mm | Brose: 197mm


• Motor System Compatibility: Bosch CX Gen4/5, Bosch SX, TQ HPR50, Brose S Mag, DJI Avinox, Yamaha, Specialized (2.2/3.1)


• Material: Forged AL 6066-T6 Aluminum


• Pedal Thread Interface: Includes Steel Pedal Washers


• Extraction Mechanism: Integrated Alloy Self-Extractor System


• Protective Hardware: Molded Composite Crank Boots Included


• Weight: 481g


• Color: Black


• Warranty: 5 Years

A durable, value-optimized alloy e-bike crank arm upgrade combining a rock-clearing 155mm profile with a generous 26mm offset, built for trail riders who demand high-end e-MTB strength, pivot clearance, and reliability without the premium price tag.