Recently, we received our custom René Herse chainring bolts (above). Why in the world would we go through so much trouble and expense to make custom chainring bolts?
They are pretty significant little bolts, because they are the finishing touch on the René Herse cranks. René Herse chainrings are 1 mm thicker than most chainrings. This is to make them stiffer, compensating for the small bolt circle diameter. However, modern chainring bolts are designed for thinner chainrings. They are slightly domed to make their heads deep enough for full engagement with the 5 mm Allen wrench, but their edges don’t sit flush with our René Herse chainrings.
Classic Herse cranks had flush chainring bolts. We don’t know whether the “Magician of Levallois” had custom bolts made, too, or whether bolts with a thicker, flat head were available off the shelf back then. I do suspect that he would have the “correct” bolts custom-made rather than compromise. And so that is what we did.
Our new bolts have a flat surface and sit flush with our chainrings. It’s a small detail, but to us, it’s important. As custodians of the René Herse name, we have to strive for perfection…
We also offer the new bolts separately. That way, customers who bought their Herse cranks with the “domed” bolts can upgrade their cranks to the Herse bolts. The new bolts also are useful for restorations of René Herse bikes.