If you think that three bolts aren’t enough to support bicycle cranks, think again. Here’s a look at the Sugino alloy Maxy II that was on the 1976 Windsor Carrera I rehabbed.
Similarly, you could look at how the weeks were attached on the Renault LeCar.
Or, look at this version of the Daimler Smart Car:
here’s what Compass said about the three-bolt design when they introduced the cranks:
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.