Introducing Rene Herse One-By Cranks

Introducing Rene Herse One-By Cranks

After months of R&D and testing, we’re now offering Rene Herse cranks with a 40-tooth one-by chainring. One-by is a great idea: Get rid of the front shifts that always break your rhythm, and you end up with 11 or 12 consecutive gears. For most riders, that’s enough for all our riding – unless you’re a professional sprinter with an entire team to give you a leadout on the way to the finish line. One-by allows you to focus on the ride and think less about the bike.

One-by cranks have chainrings with alternating ‘thick-thin’ teeth that mesh perfectly with the inner and outer links of your chain. Otherwise, the chain will just fall off in the highest and lowest gears, where it runs at the most extreme angles. One-by chainrings also have taller tooth profiles that engage the chain earlier and more securely. (You don’t want the chain to climb over the teeth, as it would during a front shift.)

Key to good performance with a one-by drivetrain is a good chainline – you’re cross-chaining in the outer gears, and if your chain isn’t aligned with the middle cog, the cross-chaining will be even more extreme at one end of your gear range. The square-taper bottom brackets of Rene Herse cranks allow you to fine-tune the chainline by changing the spindle length of your BB. An 110 mm SKF BB will give you the same 45 mm chainline as modern road cranks. If you need extra room because your bike has very wide chainstays, go to a 113 mm spindle, or even wider, to a 116 mm.

Most other cranks these days have integrated spindles, and manufacturers make their one-by cranks so wide that they fit almost any bike. Apart from the wide Q factor, this also offsets the chainline to the outside. When you’re in the bigger cogs, the chain is noisy, shifting can be sluggish, and your drivetrain wears quickly. Fine-tuning your chainline allows you to optimize your drivetrain for your bike, rather than run a crank that’s designed for the widest chainstays out there.

We offer Rene Herse one-by cranks in two versions. The first one has dedicated arms for a single chainring. That’s the most elegant solution, and it’s also a few grams lighter. (Our one-by cranks weigh just 467 grams. Even after adding the bottom bracket, that’s still lighter than most other cranks.)

We also offer our one-by cranks with arms that can accommodate two (or even three) chainrings. In this case, our custom-machined chainring spacers take the place of the inner ring. That way, you have the option to convert your one-by to a double in the future. Simply install two new chainrings (and a front derailleur), and you’re ready to go. It’s nice to have the option if you find that you really want a closer-spaced rear cassette and need a few extra gears.

The cost of both versions is the same, simply choose the one you prefer. Like all our cranks, the one-bys are available in three lengths (165, 171, 177 mm). The arms are net-shape forged (with a dedicated forging die for each length). That makes them ultra-strong, and they pass the most stringent EN Racing Bike Standard for fatigue resistance. It’s good to know when you’re riding hard on bumpy terrain!

The spacers and chainring are available separately, too, so you can convert any Rene Herse crank to a one-by. It’s always our goal to make our parts backward- and forward-compatible – less waste and more money left over for great cycling adventures.

What about other chainring sizes? We started with a 40-tooth, because we feel it’s the most versatile size. Other chainrings will follow. Which tooth count would you like to see?

The one-by cranks are now in stock. Click here for more information about our crank program.

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Comments (23)

  • Toby Whitfield

    I definitely would be interested in something at least a step smaller – 34 or 36. I’m setting up a 1x bike right now. Am going to use a 38, because that is what is available for my setup, but would consider this is a 36 or 34. Of course, part of this is the cassette sizes that are available – I would like cassette options more in the range of 11-46 or 11-50 in a 12 speed for a more offroad biased bike, but with road q factor and shifting. There are ways of doing it, but a bit smaller chainring makes it easier.

    Also, given the ease of changing chainrings on the RH crank, having 2 different chainring options means being able to change it out depending on the ride.

    November 10, 2020 at 8:08 am
    • Spirit Cyclery

      Being in a mountain town, we would very much like to have the same options available as requested by Mr. Whitfield!

      November 10, 2020 at 2:27 pm
    • Weston Hein

      I would love to see a 34t option as well!

      November 10, 2020 at 7:53 pm
  • Damian

    Can I ask what the difference is between your existing crank arms and the one-by version that has arms that can accommodate two (or even three) chainrings? Am I missing something? Thanks

    November 10, 2020 at 8:24 am
    • Jan Heine

      There’s no difference in the arms. That’s how they are backward- and forward-compatible.

      November 10, 2020 at 8:54 am
      • Derek

        Is there a difference between the non-convertible 1x arms and the single cranks you already offered, or is it just the new chainring design?

        November 12, 2020 at 7:30 am
        • Jan Heine

          The arms are the same. So you can convert a Single-Speed/Fixed-Gear arm to One-By (or vice versa). We try to keep our products compatible as much as possible.

          November 12, 2020 at 7:48 am
  • Steve P

    Looks great!!! 42T would be ideal.

    November 10, 2020 at 9:22 am
  • Singlespeedscott

    Probably a stupid question but would these work with Campagnolo’s Ekar 1 x 13 chain?

    November 10, 2020 at 9:57 am
    • Jan Heine

      We haven’t finished tested this yet, so stay tuned…

      November 10, 2020 at 10:13 am
  • Douglas Brooks

    A 40t is far too large for me. There are virtually no flats where I ride, I’m always looking for more gears and I ride to climb (about 90% of the time). I ride in my small double ring (or triple middle) nearly all the time. That would be 34t to 28t on my usual TA ProVis5 chainset. In fact, I just put that crank on a traditional “race” bike but couldn’t get the front shifter to work properly but in the bike stand—in the real world it wants to drop. But I don’t really care. I’m “stuck” in the middle ring, it’s a 32t, I have 11-34 11 speed in the rear and I get the excellent low Q factor of the TA cranks and with the triple is effectively “stuck” in the 32t ring, I could really care less. However, if I were “stuck” in a 40t ring that would not work for me.

    November 10, 2020 at 3:44 pm
    • Jan Heine

      I don’t think one-by cranks are intended for road gearing with an 11-34 cassette. If you want to run that, we recommend an ultra-compact double, like a 42-28. That’s what I run on my Firefly. I use it as a 42T one-by 90% of the time, but if the road gets really steep, I shift to the small ring. I only need that shift a handful of times during a long ride, so it’s not a nuisance like the constant front shifts you need with a more traditional road chainring combo.

      For a one-by, you want at least a 40-tooth largest sprocket… Another factor is your wheel size. If you run a 700C x 55 mm tire like our Fleecer Ridge, your wheel diameter is way larger than it is with a 26″ x 2.3″ Rat Trap Pass – you’ll need a smaller chainring with the bigger wheels.

      November 10, 2020 at 6:43 pm
  • Bernard Leeds

    Chain ring options? For the old and slow, looking for a 34 or 36T to go with my 11-46. ?
    Chain line? How compute spindle length needed?

    November 10, 2020 at 4:37 pm
    • Jan Heine

      The first one-by chainring is a 40-tooth. I think a 34- or 36-tooth makes a lot of sense.

      The chainring is in the same position as the outer ring on our other cranks: With a 110 mm SKF BB, you get a 45 mm chainline. (With a double, the chainline is measured between the two rings, so it’s 43.5 mm.) You can calculate from there…

      In practical terms, we recommend a 110 mm SKF BB if your chainstays are more or less standard. If they are wider than normal, a 113 mm spindle gives you a little extra room. A 116 mm spindle is great for really wide chainstays…

      November 10, 2020 at 6:36 pm
  • Colin Cox

    I love the multi ring adaptability. Genius! Whenever I’m wishing you would come out with a certain product, I don’t have to wait long.
    Fantasizing over RH mountain bike tires.

    November 10, 2020 at 10:03 pm
  • Stuart Fogg

    I use two rings but the difference between them is small. That gives me one extra gear with no awkward shifts.

    November 10, 2020 at 11:31 pm
    • Jan Heine

      I’m with you: I really like the 46×36 ‘cyclocross’ gearing. A front shift is the same as two rear shifts. But you also get a lot of duplicate gears and a gear range that isn’t very wide. In the end, I’ve been running a one-by on my ‘cross bike, and perfectly happy with it.

      November 11, 2020 at 7:49 am
      • Stuart Fogg

        Mine is even worse, a front shift and a rear shift are the same (about 13% average) so all but one gear are duplicates. But I use a wide range rear and don’t need particularly high gears so it works well for me. Also the chain line is a little better than with a 1X front.

        November 12, 2020 at 1:01 am
        • Jan Heine

          You’d be interested in racer gearing during the 1940s and 1950s: Five speed in the back and 51×48 chainrings. The result was a 6-speed: You’d use the three smaller cogs with the inner ring and the three bigger with the outer. In other words, only the middle cog was used with both chainrings. The advantage was that the chainline was never more than one cog from straight. Racers thought back then that cross-chaining really increased the resistance of the drivetrain.

          November 12, 2020 at 7:51 am
          • Stuart Fogg

            I was born in 1949 so that thinking might be in my DNA. Lacking racer strength I’m using 51×45 chainrings with a 9-speed 15-38 or 16-40 Frankenstein cassette.

            November 12, 2020 at 10:26 am
  • Derek

    I’ve tried 1x on a tandem and really liked it, but went back to 2x for the range. Still wishing for a short arm option for my tandem stoker. No, 165 mm is not short. I’m talking about 150 mm.

    November 12, 2020 at 7:41 am
    • Jan Heine

      It would be wonderful to offer more crank lengths. However, with net-shape forging, we make a forging die for each length – cutting cranks to different lengths weakens the grain structure – so it’s very, very expensive.

      November 12, 2020 at 7:52 am
  • Dave

    I thought I’d post here with a follow-up on the post intro introducing the Oracle Ridge. I finally wore out the stock tires on my Checkpoint and replaced them with your 48mm extralight tire—an amazing upgrade for both road and trail. However, the fit is pretty snug so I don’t see how the 55mm would fit as you said. Just a note for any future readers who might google this.

    Never thought I’d have this much traction in snow!

    November 12, 2020 at 6:25 pm

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