Testing Prototypes

Testing Prototypes

Product development is fun, because we get to think about bike parts, figure out how to improve them, and then test them on our adventures. This summer has seen plenty of excitement in that respect. Some of the parts we’ve been testing are almost ready to go into production; others are still some ways off.

It’s been an open secret that we are working on a knobby version of our 26″ Rat Trap Pass tires. While 26″ has almost vanished from the new bike market – outside a few custom builds like my Firefly – there are literally thousands of wonderful old mountain bikes. With a set of super-supple tires, they can become anything from a bikepacking rig to an ultra-fast all-road machine.

The new knobbies will add even more to the appeal of these bikes. Of course, we don’t make replicas of classic tires: The new tires will feature our proven dual-purpose tread and the next generation of our noise-cancellation technology. Like all our knobbies, the new tires combine the performance of a good racing slick with the grip of a knobby.

The Firefly has seen a lot of testing duty lately. Here’s a spy shot of a chainring marked ’40S.’ Being able to run a One-By with a Rene Herse crank will be a great option.

We like to keep our parts backward- and forward-compatible. With the One-By rings, we’ve also developed chainring spacers that take the place of the inner ring. That way, you can convert any existing Rene Herse crank to a One-By. Or you can run two chainrings on your One-By crank in the future.

We’ll also offer the One-By cranks with our dedicated single crankarms. That way, you’ll get a little less weight and a little more elegance.

Brake performance is only as good as the system’s weakest link. For many cantilever and centerpull brakes, the weak link is the cable hanger. I was reminded of that not long ago, when we tested an affordable randonneur bike with brakes that performed worse than expected. At first, I thought the setup – with too much toe-in – was to blame. After the Bicycle Quarterly with the test report went to print, I finally realized that the cable hanger – a stamped piece of flat steel – flexed so much that the entire brake felt mushy and lacked power. And yet stiff cable hangers are rare. That is why I drilled the stem on my Mule, to provide an anchor for the cable housing that doesn’t flex.

Clearly, a stronger cable hanger is needed. Using Finite Element Analysis, we optimized the shape of our prototype to minimize flex. My Mule with its flex-free setup is a great bike to test it: Riding the bike on the same course before and after installing the new cable hanger provides a good comparison. I’m happy to report that even under full braking from 40+ mph on an 18% downhill, brake performance is as good as with the flex-free setup.

We’ve also designed the hanger so it lines up with our brakes: One reason why Rene Herse’s bikes were so elegant is that the brake cables ran parallel to the head tube and seatstays. That way, they seem to disappear. It’s the same idea as a good fenderline that emphasizes the roundness of the wheel and makes the fender disappear.

Designing an ultra-stiff cable hanger was hard enough, but producing one is even harder. First we wanted to forge it, but the shape isn’t suitable for that. (You’d have to forge a flat piece first and then bend it, but bending aluminum weakens it.) CNC-machining is the only feasible option, but that means carving it out of a big block of aluminum. That is a bit wasteful in this case, where 90% of the material gets carved away (even though the aluminum chips get recycled), and expensive. We’ve decided it’s worth it, but we also understand why there are so few really great cable hangers out there…

Those are just a few of the new projects that are in the works. There’s also a certain rear derailleur that is now in the third prototype version. I rode the first prototype in last year’s Paris-Brest-Paris and loved it. The second version was designed to handle a wider spread of gears. The third version has further improvements and is (probably) the final model that will go into production.

We’re really excited about these parts, and we can’t wait to offer them to our customers, too. But until that happens, we want to test them more. All too often these days, customers are unwitting ‘beta testers,’ who get to try out new products before they’ve proven themselves. Here at Rene Herse Cycles, we only introduce new parts after they’ve been ridden many thousands of miles. That takes a little more time, but it means that if you see something in the Rene Herse program, you know that it works.

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Comments (77)

  • Garth


    I’m thinking about force vectors with the cable hanger, but was it not feasible to forge a flat one? Why does hanger need vertical part that hangs down anyway? Would it even have to be forged or could it already be a harder aluminum and maybe a little thicker?

    Excited about your Nivex derailleur. Assuming the Twin cable shifter unit will be adaptable to down tube mounts?

    September 5, 2020 at 9:00 am
    • Jan Heine

      The stem gets in the way of the brake cable, and you want a smooth radius to reduce friction. So you have to offset the cable hanger downward. Yes, the Nivex shift lever will fit on standard downtube shifter bosses. That way, you can retrofit any bike by brazing on the chainstay mount.

      September 5, 2020 at 9:09 am
      • Conrad

        Does anybody want to start a pool on how fast those 26×2.2 tires sell out?

        September 5, 2020 at 9:34 am
      • Benz Ouyang

        I’m definitely interested in a cable hanger that’s a bit more svelte than the Paul’s Funky Monkey and the many “commodity” versions currently available. I was even considering the Jitensha Studio front brake cable stop for $85 (!), but they are sold out (Double !). Your prototype appears to lack a barrel adjuster. Are there plans to include that functionality?

        September 5, 2020 at 11:03 am
        • Jan Heine

          We don’t like barrel adjusters, since they always introduce additional flex. It doesn’t make much sense to make a super-stiff cable hanger and then trade some of that stiffness for pay in the threads of a barrel adjuster. And then you have the issue of adjusting for pad wear on cantilever brakes: If you use a barrel adjuster for that, the angle at which the pad hits the rim changes, and there’s a risk of the pad diving under the rim. Then you lose all braking! (Don’t ask me how I know!)

          September 5, 2020 at 11:14 am
  • Owen Sindler

    Can you tell me more about the rear derailleur you are prototyping. It’s very attractive and I’m intrigued. I’m running a 38 x 28. Will this work for me.

    September 5, 2020 at 9:04 am
    • Jan Heine

      The Nivex derailleur starts with a clean sheet of paper, so it’s not retrofittable on existing bikes without adding a derailleur hanger on the chainstay. The advantage of that location is that the derailleur is tucked into the rear triangle, keeping it out of harm’s way when the bike falls over (no more bent derailleur hangers!) or when you graze rocks (no more ripped off derailleurs). The industry is unlikely to move away from the archaic dropout-mounted derailleurs, so we don’t expect to sell a lot of these. But the alternative would be making something that isn’t much better than what’s already out there – why bother?

      September 5, 2020 at 9:13 am
      • Ron

        I’m not that familiar with this design, although I’ve seen a few pictures on your bike and elsewhere. This is not an indexed shifting solution, is that correct?

        September 7, 2020 at 9:25 am
        • Jan Heine

          It can be indexed without much trouble, since it shifts with precision (neither early- nor late-shifting). But the indexing is a bit tricky to set up. Since there is no cable housing, there’s no place for a barrel adjuster. There are ways around that, but we’re still testing different solutions.

          September 7, 2020 at 12:34 pm
  • Jon Gehman

    Thanks for the photos of your Nivex prototypes! None of the photos of the originals I’ve seen allowed me to figure out how the tension spring actually functioned.

    The Nivex always seemed like a superior device, from it’s rigid, out of the way mounting, the way the pulley more naturally followed the profile of the cog-stack, to eliminating the return spring in the parrallelogram and the compromises that come with it. I’ve thought alot about trying to make my own but knew I didn’t understand some of it’s subtleties it well enough. Now I understand it FAR better.

    I’m eager for the Rene Herse version to be available, if I can afford it I think I’ll abandon the idea of making my own. I enjoy making parts from scratch but that was a bit daunting.

    September 5, 2020 at 9:13 am
    • Jan Heine

      There’s a lot more to the Nivex than is apparent at first sight. Making a one-off would be a daunting project. It would be easier to find a 1930s original, overhaul it and use that – as I did on my first bike with a Nivex derailleur ten years ago.

      When we offer our Nivex, it’ll be more reliable than the derailleurs from the big makers, shift better (with a downtube shift lever) and be competitive in weight. All the parts that wear (shifter cable, pulleys) will be standard parts you can buy at any bike shop. And the rest will be fully rebuildable (with a full spare part support).

      September 5, 2020 at 9:21 am
      • Jon Gehman

        Is it too soon to ask how much the Rene Herse version might cost?

        September 5, 2020 at 4:33 pm
        • Jan Heine

          Unfortunately, yes. To be honest, we don’t develop products to a target price. We make them the best we can, and sell them for the price that is the result. So we don’t know what they’ll cost until development is complete. We usually figure that our overhead is so low that even with all that R&D and our small production runs, the price will remain affordable.

          September 5, 2020 at 4:41 pm
  • Ted Rzad

    Slight correction: ‘almost’ no one makes a good cable hanger….the Paul hanger is dead-on great. I’ve had one on my 1” threaded Salsa for years with no complaints. Aesthetically, I’m sure the RH offering will be more minimal, probably lighter, and certainly a welcome additional option, but we must give credit where credit is due 🙂

    Will the RH hanger be milled from forged billet? 7000 series?

    Looking forward to your derailleur! An ambitious and quirky choice of project, yet resonant with both the Herse legacy and the pragmatic innovation of the new Rene Herse under Jan’s leadership. Bravo!

    September 5, 2020 at 9:22 am
    • Jan Heine

      I had forgotten about the Paul. Since it clamps to the stem quill, it needs more exposed stem than I have on my bikes… Thank you for the note – I changed the text of the post.

      September 5, 2020 at 9:31 am
      • Benz Ouyang

        Jan, the front Funky Monkey comes in 3 different clamp sizes, including 25.4mm for clamping onto a bare 1″ steerer. My only issue with them is aesthetics, which of course is subjective; but most steel steeds with classic equipment do not pair well with The Funk Monkey’s modern blocky design.

        September 5, 2020 at 11:11 am
  • Reid Harding

    Looking forward to the Nivex release. A couple of questions. Will it install on a bike that has an original Nivex mount on the chainstay? Would like to install on my Singer tandem. Next, is there provision to adjust the spring tension to accommodate the chain weight of a front drive tandem?

    September 5, 2020 at 9:54 am
    • Jan Heine

      It should fit on an old Nivex mount. The arms of the new derailleur are a bit longer than on the original to make it 11-speed compatible, but most old bikes had a chain gap that was larger than necessary (and ideal). The spring should be strong enough for tandems, since the compensator arm keep the tension constant in all gears. If more tension is needed, we could make a stronger tandem spring.

      September 5, 2020 at 9:59 am
  • Frederic

    Do you plane to build a front derailleur?

    September 5, 2020 at 10:21 am
  • John Q.

    29er 2.4 & 2.6 knobbies would suit a couple of my bikes quite nicely. I run a variety of your tires on other bikes but those two size editions with your new knobbie tech. will be a nice addition.

    John Q.

    September 5, 2020 at 10:23 am
    • Jan Heine

      How about the Fleecer Ridge 29″ x 2.3″? Not quite as wide as 2.4′ or 2.6″, but I think you’d like them.

      September 5, 2020 at 11:15 am
  • Reid Harding

    Thanks Jan, Considering that the arms are longer, what is the distance the braze on should be mount from the rear dropout? This distance on the Singer tandem is ~90mm. I see your more recent prototype has the top jockey wheel ear carved away for clearance for larger cogs. This may provide some leeway for installation where the positioning is less than optional.

    September 5, 2020 at 10:36 am
  • Michael

    Will the brake hanger be compatible with threadless too? If so, I need to tell my frame builder!

    September 5, 2020 at 10:58 am
    • Jan Heine

      We’re thinking about making different versions. No final plans yet.

      September 5, 2020 at 11:14 am
  • Noah

    I’m holding out for a 650bx2.2…

    September 5, 2020 at 11:11 am
  • marmotte27

    I think, the Nivex will be the first part for a new bike for me.

    September 5, 2020 at 11:11 am
  • William Schmitt

    Will you use a 5mm pulley bolt or go French with hard to find 6mm bolts?

    September 5, 2020 at 11:37 am
    • Jan Heine

      There are many reasons to go with a 6 mm bolt, mostly because of the stiffness of the bolt. It stiffens the derailleur, so you can make the cage pieces a lot lighter. The advantage is similar to going from a 9.5 mm quick release axle to a 12 mm thru-axle on a disc brake fork. We’re designing the pulleys so the bearings can be replaced if they ever wear out. (They are standard bearings, but protected with additional shields from contamination.)

      September 5, 2020 at 11:57 am
  • William Schmitt

    That should help those of us who have to replace our worn pulleys on French derailleurs!

    September 5, 2020 at 12:03 pm
  • David L.

    I love the Tektro fork crown mounted cable hanger. Feels solid under hard braking. Great for eliminating squeal. Totally recommend trying one! I’ll be putting one on my Prairie Crow (Minneapolis Frame Builder) that will be using the Mule tubeset.

    September 5, 2020 at 12:50 pm
    • Jan Heine

      The Tektro hanger looks stiffer than many, but it’s ‘standing’ rather than ‘hanging’ configuration is not ideal. Generally, stressing a hanger (or anything else) in compression/torsion rather than tension flexes it more. That is why spokes can be so thin (tension) and stems must be very large (compression/torsion).

      If you fork isn’t well-designed – too stiff at the bottom and too flexible in the upper parts – and you get brake judder, then mounting the hanger close to the brake can help solve that problem, and the Tektro hanger may be a solution.

      September 5, 2020 at 1:47 pm
  • Gunther

    Ad brake cable hanger. NIce unobtrusive design. Probably, there will be a slotted version for Rinko-bikes, I guess.

    September 5, 2020 at 1:08 pm
  • Matt G.

    Exciting news!! Looking forward to the cable hanger. I have always been dissatisfied by the amount of flex I see in my hanger, and I have tried several. Also, can’t wait to try the One-By ring. I was wondering what setup you are designing the derailleur around? Wide range double, triple? Would it work with a One-By setup? If so how large of a cassette would it work with? Thanks!

    September 5, 2020 at 1:20 pm
    • Jan Heine

      The upper pulley of the Nivex is concentric with the pivot, so you front chainring size doesn’t affect its geometry. So you can run anything – single, double, triple with any chainring differences – as long as you stay within the chain wrap capacity. However, the same feature also means that it can’t swing to accommodate huge cog ranges on the rear. We’ll make sure it works with a wider range than the original, but you won’t be able to run a 10-52 cassette with it!

      September 5, 2020 at 1:35 pm
      • Stuart Fogg

        I’m using a 45T small chainring and 38T large cog hoping larger gears will reduce stress and wear in the chain. A medium-cage Ultegra rear derailleur shifts it fine even though its maximum cog spec is 32T. Do you think your Nivex might be able to manage 40T or 42T?

        BTW congrats for creating so much interest with such interesting products!

        September 6, 2020 at 4:43 pm
  • Benjamin Meyerson

    Great news on your commitment to 26″, still many of us rolling on those and most of the other tire makers have quit making any of their higher end and especially tubeless tires in 26″.

    I have always hoped you would make the Rat Trap Pass in an endurance casing like most of your other tires, have used both the extralight and standard casings and would love a bit more protection for both urban commuting and gravel use.

    September 5, 2020 at 1:27 pm
    • Jan Heine

      The Rat Trap Pass has been available in the Endurance casing for quite a while now.

      September 5, 2020 at 1:31 pm
  • Rob Beard

    I’d really like to see those 26 inch tires in a 40cm size. That would be amazing!

    September 5, 2020 at 1:30 pm
    • Jan Heine

      We’re aware that many older mountain and touring bikes don’t fit 2.3″ (54 mm) tires. So a narrower version is definitely an option we’re considering.

      September 5, 2020 at 1:42 pm
      • Toby

        Are these tires planned to be around 2.3? I’m planning a new project, and waiting to decide between keeping an old 26″ frame, or getting something that fits 650b. If I could use these tires, I might keep the old bike and upgrade it.

        September 5, 2020 at 2:10 pm
        • Jan Heine

          The tires will be around 55 mm wide, depending on your rim, casing and inflation pressure. The nominal 2.3″ size refers to the air volume, which is the same as a typical 2.3″ mountain bike tire, but the actual tire is a bit narrower since it as a round profile, rather than a square one with knobs sticking out sideways.

          September 5, 2020 at 2:22 pm
  • Alain L.

    Cool hanger. What’s the offset BTW? My current hanger is 30mm, and would love to replace it with a better quality, stiffer hanger that is 30mm or more.

    September 5, 2020 at 3:58 pm
    • Jan Heine

      Horizontal offset from the center of the steerer axis, or vertical offset from the headset spacer to the housing stop? Also, this is just a prototype – the final design will probably change a bit.

      September 5, 2020 at 4:18 pm
      • Alain L.

        Both actually… how far does the hanger stick out horizontally (clearance over the bottom headset cup), and how far does the hanger drop vertically? Thanks!

        September 6, 2020 at 4:28 pm
  • george recker

    Finally, maybe I’ll get to finish the Divide route without having to explain to people that I do fine on the road version Rat Traps,( extra lites) excepts Elk Pass in the rain and Lava Mt climb. Sign me up for a pair .

    September 5, 2020 at 5:35 pm
  • Paul Richard

    I’ve been the Rat Trap Pass tires alive the day your released them back in …. maybe 2014? They have been the most incredible riding experience! Fast on the road, but I can take on almost everything off road short of true mountain bike terrain. I’m on my third set of Extralights. I’ve been so eagerly waiting for the knobby version. Your first run will probably sell out quick. Hope I can get a set. Thanks for making the parts that we want! I love your approach to R&D.

    September 5, 2020 at 5:53 pm
    • Paul Richard

      Couple of typos in my post.

      September 5, 2020 at 5:54 pm
  • Gran

    What an amazing post. It would be a privilege to beta test this stuff (•‿•)

    September 5, 2020 at 7:03 pm
  • Lawrence Vargas

    I’ve been thinking of these projects still, after seeing them on your latest Rene Herse, and I’m glad to see more progress! The hanger is new to me!

    I’m most excited for the Nivex Derailleur and bottom bracket! By the way I hope the bottom bracket is also coming together nicely?

    I look forward to the next updates!

    September 5, 2020 at 11:25 pm
  • César


    I’m eagerly awaiting those Rat Trap Pass Knobbies, can we know what the final name of those will be? Also, the 26×2.3 or 58-559 size as engraved in the casing will be effective or closer to the measurement of the current slick Rat Trap Pass? (Mine currently measure 51mm in an old set of Specialized Z-23 rims from 1994 at 25psi, and my frame could take some 5mm more without issue)…

    Kudos to you for developing a new derailleur, and improving on an old design, this is something that the industry will not do and it is one of those things that truly create progress. Will the pull ratio of the derailleur make it compatible with Shimano indexed downtube shifters?

    Thanks !!!

    September 6, 2020 at 2:57 am
    • Jan Heine

      The derailleur will have its own shift lever. It’s got desmodromic actuation, with the cable looping around and pulling the derailleur in both directions – there’s no return spring, which makes for faster, lighter shifting.

      September 6, 2020 at 7:30 am
      • Frederic

        Will you supply the same shift lever for the front derailleur?
        It would be more aesthetic to have the same supplier for both levers.

        September 8, 2020 at 2:09 am
        • Jan Heine

          We will offer a left shift lever, too. It’s more complex than it appears at first, since we want it to match the great performance of the Nivex. So a simple friction lever won’t do.

          September 9, 2020 at 8:44 am
  • volvimus

    Great news for us 26-inchers out here… 🙂
    Any chance, you will also introduce high quality 26″ rims, something like the belgium + or the pacenti brevet in 559mm? Available options (especially for rim brake) seem to be limited to heavy 500g + ones…

    September 6, 2020 at 4:05 am
    • Jan Heine

      There’s still the Velocity A23, but you are right, 26″ rims aren’t easy to find these days. It seems that most of the industry has given up on the size.

      September 6, 2020 at 7:32 am
  • Pierre Muron

    Exiting development. Just going to put it out there that many of us are eagerly waiting on an expanded 650b range, more so than 26”. I do love my 48mm (both in their slick and knobbies versions), but sometimes just need a bit more volume for these drop bar colorado high alpine adventures. So still lobbying for something like 650bx53-55mm!!!

    September 6, 2020 at 10:25 am
  • kais

    by making the cable tensioner design more 3d than its present 2d configuration it could have been made (a lot) stiffer with less material;)

    maybe the next iteration?

    September 6, 2020 at 11:00 am
    • Jan Heine

      You mean the chain tensioner arm? That weighs less than 2 g in its current configuration, so there isn’t much potential for taking off weight.

      September 6, 2020 at 12:45 pm
  • Nemo Brigatti

    How does the mounting mechanism for the Nivex loook like? I have an 90ies touring frame from Basso with (presumably) a braze on mount for a Suntour S1 and I am wondering whether it could be compatible with a Nivex derailleur.

    https://pin.it/7gD8VAS (picture to give a vague idea)

    September 6, 2020 at 11:38 am
    • Jan Heine

      The S1 was clearly inspired by the Nivex, but I suspect the mount isn’t compatible. Brazing on a new mount – on any bike – is easy, but it means the paint gets messed up.

      September 6, 2020 at 12:44 pm
  • Jacob Musha

    Is there a reason to use chainring bolt spacers instead of simply using shorter “single-speed” chainring bolts as I’ve always done?

    I’m very excited about the knobby Rat Trap Pass and Nivex derailer! Maybe it’s time for a new bike. 🙂

    September 6, 2020 at 2:08 pm
    • Jan Heine

      The shorter single-speed chainring bolts need a recess in the chainring tabs. You could use a round washer – Campagnolo made one in the 1970s – but it would look unfinished and not so nice. So we custom-machined a washer that sits flush with the chainring tabs…

      September 6, 2020 at 3:35 pm
  • Bicycle Safari

    Very exciting stuff! I’m hoping the derailleur can handle 34t in the rear and 24t up front.

    September 6, 2020 at 3:10 pm
  • Arnaud

    Hi, great prototypes ! I’m very glad some companies like yours still value and improve some of the “old” ideas. Very often they still have a lot of forgotten advantages to offer.

    I’m currently restoring an old French Tandem, that used the “Grand Prix Dural” Simplex rear derailleur. Do you think my existing mount will be compatible with your product ? I’m afraid not since the Simplex style mount looks much closer to the rear axle than the Nivex one…


    September 6, 2020 at 9:09 pm
    • Jan Heine

      Different braze-on, different location! Sorry…

      September 7, 2020 at 12:35 pm
  • craig

    rene herse 26“ renaissance rubber

    September 6, 2020 at 10:45 pm
  • scottg

    Future DIY article, desmodromic shifter conversion for parallelogram derailers and rod operation for cable operated front derailers.

    A desmodromic Suntour VX would be fun, a Di2 Herse/Nivex would be interesting too.

    September 7, 2020 at 10:14 am
    • Jan Heine

      H. Hirose converted Huret Allvits to desmodromic operation, and the results were impressive: much smoother shifting and lighter action. Electric shifting is already desmodromic, I believe – the motor pushes the chain in either direction. That is one reason why it shifts so well.

      September 7, 2020 at 12:31 pm
  • marmotte27

    Is the Nivex going to be indexed?

    September 7, 2020 at 10:38 am
    • Jan Heine

      Not sure. The indexing works well, but it’s a bit finicky to set up.

      September 7, 2020 at 12:31 pm
      • Reid

        Please don’t delay the release of the derailleur because there isn’t a good indexing adjustment solution yet.
        One solution for indexing would be designing miniature versions of the fittings used to adjust French drum brakes such as Maxi-CAR. The fittings installed at the derailleur pivot forks.

        September 7, 2020 at 2:02 pm
        • Jan Heine

          We’re thinking along those lines, but the fittings must be a lot smaller. There isn’t much room inside a derailleur!

          September 7, 2020 at 2:41 pm
  • Benjamin Meyerson

    Of course, sorry Jan, I meant the Naches Pass 1.8, my 1997 ti hardtail won’t fit the 2.3. The Naches is one of a dwindling number of high quality tubeless tires and perfect for that bike in an allroad setup, would love to see it in Endurance.

    September 7, 2020 at 1:18 pm
    • Jan Heine

      We may add a Naches Pass Endurance model in the future.

      September 7, 2020 at 2:40 pm
  • Phil Brown

    Suntour made a chain stay mounted derailleur 30 years ago, the S-1.

    September 7, 2020 at 3:21 pm
    • Jan Heine

      Yes, they did. I have one – we studied it before developing ours. The SunTour S-1 was also inspired by the 1938 Nivex, just like ours. SunTour took a lot of inspiration from French derailleurs. But then, so did Campagnolo, who bought two Nivex derailleurs before developing his first parallelogram derailleur, the Gran Sport. (Originally, Campy even used desmodromic actuation…)

      September 7, 2020 at 9:19 pm
  • Steven Aussenberg

    Is there an ETA on the 26” quiet knobbies? Definitely interested in a pair. Thanks!

    September 7, 2020 at 10:37 pm

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