Crank Bolt Wrench

Crank Bolt Wrench

Our René Herse cranks come with classic 15 mm crank bolts. They are beautiful and easy to tighten. However, it can be hard to find a matching 15 mm wrench. Most wrenches have walls that are too thick to fit inside the hole of the crankarm. (We cannot make the hole larger, since we want to use a standard extractor that fits inside the threaded hole.)
When 15 mm crank bolts were the industry standard, many companies offered crank bolt wrenches. The most famous was Campagnolo’s, but TA and others offered similar versions. These wrenches were beautiful and tactile. Aficionados sometimes called them “peanut butter wrenches,” even though I don’t know of anybody who actually has used them to spread peanut butter. Well, you could, and the chrome-plated finish should be dishwasher-safe, too!
Since most companies have gone to Allen heads for their crank bolts, crank bolt wrenches for 15 mm bolts have become hard to find. Many customers instead have used Allen head bolts on their René Herse cranks. Allen bolts work fine, but don’t look as nice.
Now we introduce a new René Herse crank bolt wrench. It’s made from tough CrMo steel, so it will tighten and loosen your crank bolts thousands of times without wearing out. (We’ve tested prototypes for over a year now.) The wrench is polished and chrome-plated, so it looks even nicer than the old-style wrenches from Campagnolo & Co.
In addition to crank bolts, the 15 mm wrench also works for track-style axle nuts. It’s much lighter and a bit smaller than a standard wrench, so fixed gear riders can easily carry it.
The thin wrench has one additional benefit: If you tighten your crank bolts to the point where the wrench starts being uncomfortable, because it digs in your hand, you have reached about 25 Nm, the recommended torque for our cranks. So you don’t need a torque wrench, yet you won’t over- or undertighten your crank bolts.
The crank bolt wrenches are in stock now. Click here for more information.
P.S.: Many of you have asked when we will have the René Herse double and triple cranks back in stock. (Single-speed cranks are in stock.) The new production run has been forged, and most of the machining is complete. The cranks just need to be checked for quality control and polished. We hope to have them in stock in a February, but we cannot predict the inevitable manufacturing delays. Thank you for your patience.

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Comments (33)

  • Phil Brown

    Quoting Jan:
    When 15 mm crank bolts were the industry standard, many companies offered crank bolt wrenches. The most famous was Campagnolo’s, but TA and others offered similar versions. These wrenches were beautiful and tactile. Aficionados sometimes called them “peanut butter wrenches,” even though I don’t know of anybody who actually has used them to spread peanut butter. Well, you could, and the chrome-plated finish should be dishwasher-safe, too!
    I’ve spread peanut butter with mine!
    Phil Brown

    January 20, 2014 at 12:07 pm
  • R. Jones

    Or you could just use a readily available Craftsman 15mm socket.

    January 20, 2014 at 1:59 pm
  • Guy Jett

    Glad I still have my old TA wrench

    January 20, 2014 at 2:42 pm
  • Norm Hill

    Any thoughts on offering different crank crank arm lengths?

    January 20, 2014 at 5:49 pm
    • Jan Heine, Editor, Bicycle Quarterly

      We want our cranks to be strong enough for all riders. This means they are net-shape forgings, and so we’d need a new forging die for each length. The “multi-length” forgings most small makers use for their cranks are significantly less strong. We are proud that our cranks are the only classic cranks that pass the stringent EN fatigue test for racing bikes, but it means that offering multiple lengths would be very costly.
      Beyond that, I don’t see any reason to offer cranks in very small length increments (5 mm is less than 3% on a 170 mm crank). It just doesn’t make sense, and I doubt anybody could tell them apart in a double-blind experiment. (I have done that experiment, and couldn’t tell a 170 mm crank from a 175 mm crank.) If there is significant demand for a 185 or a 155 mm crank, we’ll consider it.

      January 20, 2014 at 7:12 pm
      • Larry T.

        Thanks for admitting you can’t tell the crank length difference. I can’t either, but have heard all kinds of claptrap from those who claim they can. Every one of my bikes is set up with the exact same distance from BB spindle to top-of-saddle and I can’t tell the difference from one with 170 mm cranks, 172.5 or 175 mm. I consider myself fortunate in not being able to tell unless I look on the back of the arm!

        January 21, 2014 at 2:25 pm
        • Jan Heine, Editor, Bicycle Quarterly

          I am sure I could tell the difference between a 150 mm crank and a 190 mm crank, but not between a 170 mm and a 175 mm crank. Similarly, I can tell a difference in tread (Q factor) of about 7 mm, but not one of 3 mm.

          January 21, 2014 at 6:39 pm
  • Somervillebikes

    I found that most 6 point 15mm sockets are too thick to fit (unless specifically designed as thin wall), but some 12 point 15mm sockets fit. I have an SK 12 pt and a Craftsman 12 pt, and both fit despite not being marketed as thin wall.

    January 20, 2014 at 6:52 pm
    • Jan Heine, Editor, Bicycle Quarterly

      Glad to hear that the 12-point sockets fit. My sockets are 6-point, and they don’t fit…

      January 20, 2014 at 7:08 pm
      • Phil Brown

        Sadly most 15mm sockets are too big.
        But Snap-Ons work just fine.
        Phil Brown

        January 20, 2014 at 7:38 pm
    • Frank

      6pt > 12pt 🙂
      (Reason I say that is 12pt sockets apply force to the corners of the bolt-head and is more prone to slipping than the 6pt socket that applies it’s load along the sides and is less likely to slip/

      January 21, 2014 at 4:57 pm
      • Jan Heine, Editor, Bicycle Quarterly

        Even though I prefer 6-point sockets, I do believe that they all apply the load at the corners. If your socket slips on your bolt head, either the socket or the bolt is very far out of spec.

        January 21, 2014 at 6:46 pm
      • Bruce

        This would be true at higher torque, but the relatively low torque spec needed here won’t make a 12pt an issue.

        January 24, 2014 at 1:29 am
  • Jörg

    Wow, what a beautiful piece to spread peanutbutter and Nutella on my Brötchen. Would also ad value to my workshop. I will consider buying one as soon as I have the Herse cranks.

    January 20, 2014 at 9:56 pm
  • Bailey

    I’d bring that on a tour, but I prefer a torque wrench for installation. Measuring torque based on “it kinda hurts my hand now” is too vague.

    January 20, 2014 at 10:30 pm
    • Jan Heine, Editor, Bicycle Quarterly

      Fortunately, most torque settings have a range. If you torque our cranks to twice the specified torque setting (50 Nm), no harm will be done. (We tested that.) Beyond that, the human body’s perception is not as vague as we often think. Just think about how “perceived exertion” often is more accurate than power meters and heart rate monitors.
      I have never used a torque wrench, yet I haven’t destroyed a fastener or had one come loose in over a decade of working on bikes. (Before that, I made some mistakes as I gained experience.) Most of all, a good wrench is designed so that you can put proper torque, but not much more, onto the bolt. That is why an 8 mm wrench is much shorter and thinner than a 15 mm wrench…

      January 21, 2014 at 7:15 am
  • Bailey

    I should’ve added, “for many folks”, to the end of that; as an experienced mechanic generally knows how tight a square taper crank should be.

    January 20, 2014 at 10:35 pm
  • tom_dlg

    25 Nm really isn’t a lot of torque, especially on the left side. I believe Campagnolo used to recommend 35 Nm and 30 Nm is as low as we’ll ever go at the shop… It would be a shame to ruin such a lovely left arm from the lack of torque!
    Can you elaborate on this recommendation of yours?

    January 21, 2014 at 2:21 am
    • Jan Heine, Editor, Bicycle Quarterly

      If you grease the tapers, 25 Nm is all you need, based on our testing. If you don’t grease the tapers, you don’t get a consistent fit, and so you have to overtorque the cranks to be on the safe side.

      January 21, 2014 at 7:17 am
      • Dave

        “Common wisdom” says never grease tapers (unless you can’t get the crank to stop squeeking and the alternative is to throw it away). And in my experience, the (square taper) crank bolt is the only bicycle fastener that I couldn’t possibly torque to spec without a torque wrench. I’d be interested to hear why greasing is recommended with the Herse crank, and if the lower recommended torque spec (compared to recommendations by other manufacturers), combined with greasing, makes it easier to hit the mark by “feel”.

        January 22, 2014 at 3:12 pm
  • Bill Romano

    Thanks for making this wrench available Jan. $29… I wonder what Campy would charge for this wrench today? Ordering mine now.
    On a side note. I hesitated ordering my Herse crankset because of the arm length. I had been riding 175s. It took me about 3 minutes to get over it. It’s never been an issue.

    January 21, 2014 at 5:26 am
  • Doug Lowrie

    When tightening crank bolts I prefer to use a 15mm wrench first then torque in 5 foot pound increments to the manufactures spec. My small hands gives up before I reach specified torque. Your new RH 15mm wrench would be a fine addition to anyone’s tool box.

    January 21, 2014 at 5:40 am
  • Cory b

    Beautiful! I would much rather have this in my small tool box than anything else. I can’t afford the Herse cranks of my dreams but I could manage this wonderful tool!
    Jan you mention making mistakes in the past tightening cranks . Can you elaborate ?

    January 21, 2014 at 10:33 am
    • Jan Heine, Editor, Bicycle Quarterly

      Not mistakes tightening cranks, but other bolts. I once ripped off a stem bolt. I am not even sure I overtightened it, that was when I was 20! Also, the tiny bolts of the TA and Stronglight cranks (and their copies) simply are underdesigned for the torque they need, so I have stripped a few of those. To say nothing of the bolts holding Mafac brakes on the canti or centerpull studs. They seem to break with alarming regularity. It’s such a shame, the rest of the brakes are so well-designed! Perhaps that is the reason why René Herse used his own bolts instead?

      January 21, 2014 at 11:33 am
  • RosyRambler

    Jan, would your wrench work on a Stronglight 49D crankset?
    I couldn’t get any of my socket wrenches to fit.

    January 21, 2014 at 2:51 pm
    • Jan Heine, Editor, Bicycle Quarterly

      Most of the really old French crank bolts have 16 mm heads, so our wrench would not work. Those used a 23 mm (TA, Herse) or 23.35 mm (Stronglight) crank puller. We reduced the diameter of the hole to the standard 22 mm (Campagnolo and all the copies), so you can use a standard extractor to remove the cranks. That meant reducing the bolt by a millimeter, too, to 15 mm.
      Many Stronglight crank pullers came with a thinwall socket that fit the 16 mm bolt. It had two holes (on opposite sides), and you inserted a screw driver to loosen or tighten it.

      January 21, 2014 at 6:42 pm
  • RosyRambler

    I just noticed your 15mm crank bolts. Would they work on my 49D crankset also?

    January 21, 2014 at 2:55 pm
    • Jan Heine, Editor, Bicycle Quarterly

      Yes, those would work on pretty much all cranks that use crank bolts. I’ve used them on TA, to replace the 16 mm bolts…

      January 21, 2014 at 6:43 pm
  • Duppie

    Looking forward to getting a Rene Herse crank next month. Does the crank use a standard crank puller like the Park tool CCP-22?

    January 22, 2014 at 6:59 am
  • RosyRambler

    ….”Most of the really old French crank bolts have 16 mm heads, so our wrench would not work.”…….
    Rats! Would have loved to work with that tool in my hands, let alone have it in my tool collection..

    January 23, 2014 at 5:44 pm
  • rodneyAB

    Thanks for making this tool available, very nice

    January 25, 2014 at 5:50 pm

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