Bump-Proof Decaleurs


A decaleur is a quick release for a handlebar bag. It attaches the bag securely while keeping it offset from the bars so there’s room for your hands on the handlebars. (The French “decaler” means “to offset” or “to move out of the way”.) It also allows easy removal when you want to take the bag with you after parking the bike. A decaleur really optimizes the benefits of a handlebar bag.

The bag does not hang from the decaleur. Its weight is supported by a small front rack. Traditionally, decaleurs were custom-made for each bike. Many constructeurs used a system of two tubes that attach to the stem. A bar with two pins is attached to the bag. The pins slide into the tubes to connect the bag to the stem. The key to this design is getting the friction fit between the male and female pieces just right. The bag must not jump out of the decaleur when you go over a bump, yet you want to insert and remove it with ease.


This perfect fit is difficult to achieve, especially in a production setting. All pieces have  tolerances, and then there is the chrome-plating that adds varying thickness… The Grand Bois decaleurs we sell are made by Nitto. Their fit is better than most, but even with these decaleurs, the bag could jump out and fall off the bike. Grand Bois recommends attaching the bag to the rack with a strap, but that defeats the “quick release” function of the decaleur.

We looked at the problem and figured out a way to make the decaleurs more secure by tightening the tolerances at the pin connection, so that no additional straps are needed. We’ve tested this on some very rough roads, with the bag held in place only by the decaleur. The bag remained securely inserted in the decaleur.

All decaleurs sold by Compass Bicycles since April 2013 already feature this upgrade. If you bought your decaleur from us before that date, and if you experience problems with the decaleur’s pins moving out of the stem-mounted tubes, we will retrofit the decaleurs free of charge until December 31, 2013. Just mail both the bag-mounted piece with the prongs and the stem-mounted part with the tubes back to us, together with a copy of the receipt. (Our address is here.) Include a $ 10 check for return shipping (U.S. customers; $ 20 international). Allow 5 weeks for the upgrade.

Please note that this upgrade is made by Compass Bicycles, not Grand Bois. It is available only on decaleurs sold through us, either directly or via one of our retail partners.


One problem with traditional decaleurs is that their height is not adjustable. For that reason, we offer Gilles Berthoud handlebar bags in three sizes, so you can pick a bag that fits into the space between your handlebars and your rack. However, even the largest bag is not tall enough for very large frames.

Based on the idea of a Bicycle Quarterly reader, we now offer a drop kit that moves the decaleur downward (above). This is available with a drop of either 10, 20 or 30 mm. It is compatible only with Grand Bois decaleurs for Grand Bois stems.


Compass Bicycles also offers Grand Bois decaleurs for Nitto Pearl stems, as well as a generic model for aluminum stems with a horizontal handlebar clamp bolt (above). These decaleurs also feature our upgrade to hold the bag securely. They do not work with the drop kit, since their attachment bolts are horizontal, not vertical.

We believe that these decaleurs now offer the best solution for mounting a handlebar bag on your bike. For liability reasons, we cannot guarantee that your bag never will come off, but in normal riding, you should not worry about your handlebar bag flying off or rattling. It should not take more than a quick upward lift to remove the bag and take it with you.

Achieving tight tolerances is labor-intensive, and most makers don’t bother. But when I ride my bike on challenging terrain, the last thing I want to worry about is my handlebar bag!

Click here for more information on Grand Bois decaleurs.

About Jan Heine, Editor, Bicycle Quarterly

Spirited rides that zig-zag across mountain ranges. Bicycle Quarterly magazine and its sister company, Compass Cycles, that turns our research into high-performance components for real-world riders.
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39 Responses to Bump-Proof Decaleurs

  1. bostonbybike says:

    “All pieces have tolerances, and then there is the chrome-plating that adds varying thickness”

    Seriously? How thick is that chromium plating? A few micrometers – nothing to worry about. 10 micrometers is about 0.0004″. Those tubes are definitely not dimensioned that tight unless you are planning on press fitting them into the bag coupler with a hammer.

    • The chrome layer is indeed very thin, but quality triple plating first puts down copper to get a smooth surface that is easy to polish. The copper adds much more thickness than the subsequent nickel and chrome layers.

      I have seen chrome-plating adding 0.1 mm to the outer diameter of a tube. When I made my own decaleurs with Ernest Csuka of Cycles Alex Singer for two bikes, they both needed reworking after chrome-plating. The tolerances really have to be spot-on for decaleurs to work properly. As you point out, rods and tubes have tolerances, too, and you cannot really predict the friction fit beforehand.

  2. mark says:

    If the bag must rest on a rack anyway, wouldn’t it make more sense to put a small QR latch on the bottom? It could be done a dozen ways, be quick, and more secure.

  3. John Myers says:

    Great idea, but with my extra large frame the top of a 28 GB bag still is not level with the stem. In my circumstance the Gilles Berthoud system with long bars has worked.

    • It’s great if the Berthoud decaleur works for you. It does have the advantage of being adjustable, but on our bikes, the many screws tend to come loose every hour or two… We even tried brazing them solid on Ryan’s bike, but in the end, the entire decaleur just broke.

      • John Myers says:

        What was Ryan ‘s solution?

      • His solution is evolving. He junked the Berthoud decaleur and got a custom-made one by a local builder. However, that one still jumped out. Not sure whether he’s fixed that somehow or whether he just straps the bag to the rack now. At least the new decaleur hasn’t come loose or broken.

        Unfortunately, his bike has a threadless steerer, otherwise, we’d just install one of our decaleurs together with a Grand Bois stem.

    • Alex says:

      John, how big is your frame, actually, to help out other such as myself who are planning a rando bike but without the parts, so to speak . . . Cheers.

  4. David Pearce says:

    Thank you for the definition of “decaler”. I never knew. To move out of the way, that’s a useful verb.

  5. David Pearce says:

    I wonder why you couldn’t just use some sort of springy cotter pin through holes in one or both of the decaleur tubes and their matching pins? Or what about, even better, a springy single- or double-loop clip, like a big hair pin with one or two “bubbles” formed in it, fitting around grooves cut into the ends of the bag pins that are exposed once they slip all the way into and through the decaleur tubes. Either of these pins or clips would be attached to the bag by some kind of watch-type chain. I don’t think the little chain or the pin/clip would make much noise when riding, nor hinder the on-off ease very much. The clip could even live in a little “pen-pocket” on the bag when not in use, and it wouldn’t have to be used all the time.

    Maybe? I don’t know. It’s always something! ……… 🙂

  6. David Pearce says:

    Using spring steel I mean. Or two spring steel c-clips with little rings cut into a widened back, attached to one chain or leather thong for sound deadening, and otherwise living in one of the pockets of the bag or their own little pocket when not in use.

  7. corybrenn says:

    I would like to add a point on bag and decaleur sizing. I measured from the platform of my rack to the tops of my bars and came out with a measurement of about 195mm. I went with the 190mm bag thinking it would be a perfect match. I would recommend going with the next size up to accommodate for bag drop. When filled with goods, the bottom of the bag will sink a little over the sides of the rack thus dropping the bag height. A 220mm bag would of left me more level and in a better position to accept a decaleur that sits in front of the head of a stem. I also recommend the Gilles Berthoud that Compass sells. The deluxe version has a leather bottom that tends to let the bag bounce on the rack if not secured by the bottom of the bag.

    • The bag height is not all that crucial, if you remove the heavy stiffener inside the bag. Then the bag can either sag a bit in the middle, or on the sides, and since it’s flexible now, it’ll conform to the rack surface and move around much less.

  8. Neil says:

    Glad that Compass is paying attention to this important detail! Consumers might note that the Velo Orange decaleur also has addressed this issue…one must squeeze the bag-mounted prongs ever so slightly to fit them into the receiver. The bag is then rock solid. The VO product mounts within the headset stack, so not really a competing product with the GB unit…entirely different application.

  9. David Pearce says:

    My absolute last word on this topic. I like copper–the artistic application is calling me. How about this for special c-clips for the grooves at the bottom of the decaleur pins: Out of one side of a U.S. penny, you drill out a bite, like the bite out of the Apple logo, but deeper, and then break the sharp corners with a file. This will press fit around the groove at the bottom of the decaleur pin. On the other side of Lincoln (being sure of course not to drill his countenance), you drill a hole, through which your leather thong is laced, with two knots, one on each side of the penny, with some slack in between the knots for ease of use. Or, if a penny is too thick and not springy enough, then get your own copper token, with your own branding on it, and do the same thing.

    I guess copper isn’t the best for weather resistance, or is it? Well back to the drawing board.

    • The pins of the decaleur are very small – at least the ones we sell. I’ve seen many companies offer decaleurs that were way oversized – they needn’t be huge. So there isn’t really room to drill holes, thread things, etc. The friction fit, when done well, works perfectly.

  10. The drop kit you offer relies on spacers which create a lever arm on two of the most important bolts on the bike.

    VO’s discontinued stem-mount decaleur was a nice design for most quill stems that used a single longitudinal bolt, in that it was mounted to a piece of flat stock which you cut and drilled to the height that you needed, then bolted to the stem bolt. I wish they hadn’t discontinued it. Maybe it required too much DIY and that turned buyers off. But it was a great way of getting a decaleur to fit the bike exactly as desired without using spacers.

    • We tested the spacers extensively on really rough roads. There is a reason that we offer the spacers only with up to 30 mm drop. Any more, and the forces could become significant. The decaleur is not that highly stressed, because it is attached to a soft bag. Even if the bag moves, it cannot exert much torque on the decaleur.

      The Velo-Orange decaleurs had such a poor fit that it was impossible to keep the bags in place on rough roads. When VO started up, Chris K. called me to ask about products they could make. I suggested decaleurs (together with some other products). I was surprised how big the final pieces were, and how poor the fit was. The design might have had some merits, though.

      The current VO decaleur that mounts to a headset spacer has a long lever arm on a very small spot weld. It tends to break as soon as you head on rough roads. We had one member of our Flèche team with one last year, and it broke toward the end of the ride, after riding about 10 miles on gravel.

      • Frank says:

        My VO aheadset spacer decaleur was surprisingly sturdy at the spot weld, although I have treated it very badly: I bent it at the weld and used it upside down, images here: http://footils.org/2011/06/27/being-front/

        I commute through town and ride gravel roads in my spare time and the decaleur held up for more than two years.

        The bag doesn’t jump out either. This might be because the bag I used was a small VO Champagne bag. However the VO decaleur is pretty annoying in that it tends to turn left and right and loosens the headset adjustment.

        My new Rawland Stag has a bigger GB 28 bag that reaches up to the handlebars – and currently no decaleur is attached (I use the leather straps of the bag, losing a useful position for my hands this way). I plan to let a local frame builder modify my old VO decaleur so it mounts to the stem’s faceplate, using 2 of the 4 bolts there. It’s a pity that no-one makes a simple 2-rod decaleur that mounts to modern stems. Or maybe to the handlebars instead of the stem, like Klickfix or many computer/GPS mounts do.

      • You could also get a Gilles Berthoud bag designed for the KlickFix attachment. Using that bag with the KlickFix and a bag-support rack provides a very good attachment of the bag. The drawbacks are significant extra weight and a slightly clunky appearance if the bag is off the bike. And I also am not sure whether that Berthoud bag comes in different sizes, since it is designed to hang from the stem with no support (which will degrade your handling a bit and, in most cases, place the load higher than necessary).

      • Frank says:

        Hi Jan, I didn’t mean a Klickfix bag – I was talking about a traditional decaleur like the Grand Bois or old Singer/herse ones – but like the Klickfix Handlebar Bracket, it could attach to the handlebars instead of to the stem. Dozens of computer mounts are attached to the bars, the FSA Control Center and so on. It could still be lightweight as it won’t have to hold the bag itself, and it would fit regardless of stem type.

      • I prefer to keep the handlebars open for various hand positions. The stem already has bolts at the front, so it’s easy to attach a decaleur there with minimal extra weight. People add clamps to the handlebars only because the accessories were not part of the original design.

      • Neil says:

        I must say that my VO headset-mounted decaleur has not experienced any stress problems, and I ride extensively off-road, including rocky singletrack. No issues. VO makes a solid product at a fair price.

      • I am glad your decaleur is working well for you. Here is one that broke during our Flèche this year.

    • Bubba says:

      Good eye, Anton (somervillebikes). But, I think when you think it through, you’ll conclude the danger is small. First off, imagine if we had a drop kit that was 18-inches long. It would be very easy to break that off, with that long lever arm. Where would it break, though? Right where that extended bolt peeks out of the stem. Your handlebars would still be clamped securely. I think you called them “two of the most important bolts” because they hold the handlebars. The decaleur hanging off the ends adds negligible stress to the part of the bolt that is clamping the bars.

      I admit I was shocked to learn from the Rene Herse book that Herse used alloy bolts and nuts to clamp the bars on his stems. Later, he got more conservative and went to steel bolts with alloy nuts.

      • Actually, if you broke off the bolt, the handlebars would be able to rotate on the stem. (The stem isn’t threaded, but there always is a nut that secures the screw.) The drop kits we sell don’t add much to the leverage of the bag on the bolts, since the decaleur extends forward anyhow. (If the drop is as much as the forward extension of the decaleur, then the force is multiplied by a square root of 2.) That is the reason we don’t offer drop kits with very large drops.

        Most of all, we’ve tested this setup extensively before offering it for sale.

      • Bubba says:

        I take it back! My apologies for not understanding the way that stem is built.

  11. Jeffrey James says:

    My handlebar bag jumped off the decaleur and front rack when I first set up my bike. It’s definitely a scary moment when you realize you’re about to ride over your bag. My solution was to tie a piece of leather shoelace in a loop attached to the middle of the handlebar piece of the decaleur. When I place the bag on the rack and insert the decaleur pins, I stretch the leather loop around the pins and the tubes on the stem-mounted decaleur piece. This action only takes a few seconds every time I put the bag on or take it off, but the bag has never jumped off again and I’ve ridden on some pretty rough trails. The leather loop acts as a sort of tether which allows the bag to move up and down but prevents the pins from completely disengaging. It’s a very simple solution that works well for me.

  12. Alex says:

    In the first “action shot” photo, it seems like having a handlebar bag and two low-riding front racks and bags would make a bike imbalanced. Why the aversion to distributing the weight in the back? It also makes the bike look funny! I thought it was a wheelchair for a second.

    • You are right that it is common to load up the back of the bike first. The main reason for this is simple: Most bikes don’t handle well with a significant load on the front. You need a different front-end geometry so that the load doesn’t affect the steering.

      We’ve done extensive testing on how best to carry a load (see Bicycle Quarterly Vol. 5, No. 3). First, the bike actually is more balanced, not less. The rider’s weight is mostly on the rear wheel, so a front load makes the weight distribution more balanced. Second, the front wheel is stronger than the rear (no dish), so it’s better able to carry the weight. Third, it’s easier to balance a front load (the rear follows the front with a lag when you turn the handlebars), so a front load gives you better handling. Fourth, a front load is easier to lift over obstacles. Fifth, and perhaps most surprising, a front load is more aerodynamic (see Bicycle Quarterly‘s wind tunnel tests of real-world bicycles in Vol. 6, No. 1)

      So as you can see, there are many reasons to carry your load on the front, as long as you have a stiff rack (rack flex affects you steering much more on the front than the rear) and a suitable front-end geometry.

    • David Pearce says:

      Jan is right. Even on my Brompton, when I fill the shopping basket to the gunnels and click it on the front click-block, the bike handles remarkably well, more steady I think than without a load. The inertia in the steering feels heavier than one is used to on first pedaling off, but the bike is rock steady and goes exactly where you want it. Front mounted carrying looks perfectly normal now to me, and I think if you have a need for carrying only two panniers, the up front mount looks better.

      • Alex says:

        I like that about my loaded Brompton as well, but let’s not be disingenuous: the Brompton’s front load does not turn with the wheel, and that’s a large part of why it feels so ‘right’.
        (different Alex to October 28, 2013 at 4:19 am)

      • We tested that, too. A load on the frame is better at lower speeds, because it doesn’t swing the fork around. That is why mail carrier bikes in Europe use that design. The disadvantage is that at higher speeds, the bike will start to wander from side to side.

        A load on the fork is better for higher speeds, because the inertia of the load stabilizes the steering. That is why newspaper couriers in France used that design. The disadvantage is that you have to be a bit more skilled when starting and stopping.

        So each design has its advantages and disadvantages, depending on your speed and how often you stop.

  13. PY says:

    What handlebar tape is that on the bottom photo?

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