René Herse Cranks

Compass Bicycles and René Herse Bicycles are proud to introduce a modern version of the classic René Herse crank. The new crank will be available this fall.
Some products are hard to improve; they make you wonder why all components are not made that way. The classic René Herse cranks are like that. Here are some of the features that make them stand out:

• Three-arm spider to support the chainrings: Most cranks today use four or five arms, but they only add weight. Three arms support the chainrings well. Two arms would not be enough, since they do not triangulate the chainring support. (If you wonder whether three bolts can handle the torque of a strong rider, check out this Renault Alpine sports car. Its wheels attach with three bolts each.)
• 70 mm bolt-circle diameter: Herse determined that a 24-tooth chainring was the smallest chainring that riders might want. This determined the bolt-circle diameter of 70 mm. All chainrings have the same bolt-circle diameter.
• Single, double or triple: One, two or three chainrings can be bolted to the spider. There is no need to buy new cranks if you want to go from a double to a triple chainring setup.
• Unlimited chainring combinations: Since all chainrings have the same bolt circle diameter, you can use any chainring combination from 24 teeth upwards. Most cranks today use bolt-circle diameters that make it virtually impossible to set up useful combinations like 48-32 or 46-30.
• Light weight: With only three arms on the spider, only three chainring bolts, and a smart overall design, the Herse cranks are very light, lighter even than carbon-fiber Campagnolo Record cranks.
• Low tread (Q factor): Most classic Herse cranks were between 130 and 140 mm wide, even with triple chainrings.
• Great reliability: Herse cranks have been ridden to world championships. They were used on tandems that climbed the 15% hill of the Poly de Chanteloup hillclimb race in the big ring. Over decades of hard riding, they have proven extremely reliable.
• Elegance: Highly polished, with a beautiful circle pattern formed by the arms and chainrings.

The new cranks are faithful to the original design in most points. Over 2 years of research and development, we have modernized the cranks in ways that Herse might have done as well, if the technology had been available back then:

• 6066 forged aluminum arms: This alloy offers most of the strength of 7000-series alloys without that material’s risk of stress corrosion cracking.
• 7075 CNC machined chainrings: This high-strength alloy greatly increases the lifespan of the chainrings. The rings are clear anodized for protection against corrosion.
• Gently curved arms: While preserving the classic appearance, the slight curve of the arms (see photo above) provides extra ankle clearance. (Modern CNC machining makes it easier to create curved forging dies, which would have been difficult in Herse’s day.)
• JIS square taper bottom bracket: The curved arms use a shorter, and thus lighter, spindle (110 – 113 mm for double; 121 – 126 mm for triple).
• 22 mm extractor: The standard tool to remove the cranks is in almost every cyclist’s tool box.
• Compatible with 10-speed drivetrains. A little extra space between the arm and outer chainring provides room for the “sculpted” cages of most modern front derailleurs. Moving the arms slightly outward also keeps the chain from hitting the end of the crank in the largest gear with modern, wide cassettes. As a result, the new cranks’ tread (Q factor) is slightly wider than that of the originals: about 142 mm for a double. This still is lower than most cranks available today.

The new cranks will be available in the Fall with a large range of ring sizes from 24 to 48 teeth. We will offer the cranks with single, double and triple chainrings, as well as a tandem model.