Why Do We Make Custom Chainring Bolts?

CranCmBoltRingDouble_1421

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.

CranCmCrank2_A_1346

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.

Click here for more information about René Herse cranks and chainring bolts.

About Jan Heine, Editor, Bicycle Quarterly

I love cycling and bicycles, especially those that take us off the beaten path. I edit Bicycle Quarterly magazine, and occasionally write for other publications. Bicycle Quarterly's sister company, Compass Bicycles Ltd., turns the results of our research into high-quality bicycle components for real-world riders.
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11 Responses to Why Do We Make Custom Chainring Bolts?

  1. fauxtom@comcast.net says:

    Jan,   Are these bolts different from the previous RH bolts?   I bought an RH crank (thorugh Dan Boxer) in 2012.   Should I be worried about the bolts as originally supplied?   Thanks in advance.      Tom Israel Seattle  

  2. I get this. I am very fussy about track chainring bolts (for single chainring applications) and am disappointed that most manufacturers have been too ignorant or too lazy to adopt Campagnolo’s track fixing bolt refinements.
    Campag’s track bolts do not have a detente at the end, so your 5mm wrench will slide all the way thru. This is so you can stack exactly five bolts onto the Campag 5mm L (pregnant) wrench.
    Campag’s backing plate is not smooth on the outside; it is knurled, and the diameter of the track spider is slightly narrower so that as you tighten the fixing bolt, the backing plate is locked onto the spider. This means that you don’t need the two-pronged tool (which is largely useless anyway) to hold the backing plate; it is press-fit into place. The result is that with one tool, you can replace a track chainring (stacking all the bolts onto the wrench) in less than a minute. Very useful on the track when you are pressed for time.
    The problem is, manufacturers of track cranks haven’t caught on, most notably Shimano and Rotor. Using their bolts or spider, you have to epoxy the back plates onto the spider. The only track cranks I’ve seen that follows Campag’s lead has been the Sugino, 75, no longer made.
    I’m also still undecided about the merits of using Torx bolts as fixing bolts. Would there be any advantage of T-25 over 5mm? Would T-25 be less likely than 5mm to strip on removal after a hard winter?

    • I agree that having the chainring nut (what you call the backing plate) stay in place would be useful on the track, where you need to change chainrings often to get the gearing you need. The René Herse cranks with single chainrings usually have a press fit for the nut, so they will stay in place just like the knurled Campy ones…

    • Brendan R says:

      >I’m also still undecided about the merits of using Torx bolts

      These are “lawyer” bolts, and their use continues to grow for one reason. Manufacturers use them to dissuade/prevent the average rider from trying to do home mechanics. They are paranoid about being sued by mechanically inept/naive users. Such are the times we live in, alas.

      Just look at the instruction sheet of any component nowadays – full of dire warnings about injury or death unless the component is fitted by a bike workshop, even for trivial components. Manufacturers – or rather, their lawyers – just do not want owners to work on their bikes.

      Formerly, a rider on a cycling holiday could carry one set of tools – Allen keys. Now, two sets are required – Allen keys + Torqx. This is progress?

  3. Bob C says:

    I’ve got a couple of pairs of Rene Herse cranks and I can say they are exceptional in every way — best crank being made today. By far.

    But a question: when did you shift from the domed bolts to the custom bolts? Are all Herse cranks prior to this post outfitted with the domed bolts?

  4. Jp Mary says:

    Jan, vos pédaliers sont toujours incompatibles avec les shifters shimano ou campagnolo ?

    • Our cranks are compatible with STI/Ergo for two chainrings, but not with triples. Here is why.

      (Nos pédaliers sont compatibles avec les poognées STI/Ergopower doubles, mais pas les triples. Voici pourquoi.

      • Bob C says:

        I realize why as a manufacturer your official stance needs to be this doesn’t work. But FWIW, I successfully use Campy Chorus brifters with a Shimano XT front derailleur to shift my triple Herse cranks. Not a problem at all — it needs a slightly careful setup, but once that’s done and the cables stretch and settle (readjusted once) it works perfectly and shifts very fast smoothly. (The Chorus are for 11 speed Campy, but I use them to shift the triple shimano in front and a 9 speed XTR or, now, Sun XCD 9 speed rear). This setup shifts better than native Shimano triples, for sure.

      • Bob, thank you for the datapoint. I am glad your setup works for you. With some imagination, there are a lot of possibilities.

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