Compass “Hirose Design” Decaleurs

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Compass is proud to introduce what we consider the ultimate decaleur. Combining the ideas of René Herse and H. Hirose with Nitto’s craftsmanship, the new Compass decaleurs are strong, light, beautiful and reliable.

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Here is why decaleurs are important: We love handlebar bags. They are a great way to carry the things you need during your ride: accessible without having to get off the bike. The map holder on top greatly reduces your chances of getting lost, since you have your map or cue sheet visible at all times. And with a handlebar bag, your bike handles better than with a rear bag: It’s much easier to ride out of the saddle – none of that “tail wagging the dog” effect.

A little less important, the bag shields your legs when riding in the rain. On chilly mountain descents, you can tuck your hands under the flap for a little extra protection from the wind. Handlebar bags are more aerodynamic than rear bags, too. (We tested that in the wind tunnel.) Lots of pluses…

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The only minuses are that
a) you need a rack to support the bag optimally (we’ve solved that with the various racks Compass now offers), and
b) the bag attaches to the handlebars, which can get in the way of your hands in the “on the tops” position.

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Enter the decaleur, which keeps the bag away from the handlebars. (Decaler” means “to move out of the way” in French). A good decaleur also provides a handy quick-release for your bag. Just pull the bag upward, attach your shoulder strap, and take your important belongings with you when you lock up your bike. (The photo above shows the decaleur on a 1952 René Herse. The U-shaped piece on top prevents water from getting into the decaleur tubes when no bag is mounted.)

All this would be great, if decaleurs didn’t have their own problems. There are many designs, but none of the off-the-shelf versions have worked well in the past. One popular model attached to a stem spacer – and quickly broke from the vibrations as the bike rolled over rough roads. Another is adjustable in every conceivable way, but the adjustments never stayed put. A friend finally had his brazed together to make it “non-adjustable”, but then it broke, too.

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The best solution is the simple two-prong decaleur that attaches to the stem’s handlebar clamp bolts, as pioneered by the great French constructeurs. These decaleurs are strong and reliable, provided you have a perfect friction fit between the mating parts on the bag and on the stem. The constructeurs achieved that fit through careful handwork, but this has been difficult to recreate in a production setting.

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Modern versions of these decaleurs often had too little friction. On Bicycle Quarterly test bikes, no fewer than four handlebar bags have flown off mid-ride. It’s not much fun… On one bike, I was braking for a stop, and the bag flew forward, landed in front of the bike, and I rode over it. On another test ride (different bike), a BQ camera met an untimely demise when the bag ejected during a gravel descent at high speed. The third one was a poorly mounted decaleur that broke off. And the fourth bike didn’t have a decaleur, instead attaching the bag only to the rack (above)…

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When I visited Tokyo in 2014, I finally saw a solution that looked promising. H. Hirose had designed a simple locking mechanism which prevented the bag from coming off inadvertently. A spring-loaded pin on the stem-mounted part of the decaleur engaged with a groove on one of the prongs on the bag mount. Brilliant!

To release the bag, you push in the spring-loaded pin and pull the bag upward. To install it again, you align the two prongs on the bag with the tubes, and push the locking pin as you slide the bag downward. Release the pin after the bag is all the way down, and the bag is locked. It couldn’t be simpler.

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As soon as I got back to Seattle, I modified the decaleur on my “Mule” with a similar locking mechanism to test it (above). I am happy to report that it has been working flawlessly for over two years now.

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The next time I visited Tokyo, I asked H. Hirose whether Compass could license his design. He examined my prototype  – and the “Mule” I had brought along with it – for a long time, before he agreed.

While we were coming up with a new design, we thought of other ways to improve the decaleurs that Compass was selling at the time. René Herse’s last bikes had decaleurs that joined the two tubes to form a “U”. That is much stiffer, so there is less risk that the decaleurs will bend and the tubes will get misaligned.

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We worked with Nitto to put this ambitious design into production. It’s hard enough to make as a one-off, but as a production run, it’s even more challenging. We figured that if anybody could do it, it would be Nitto. And they came through.

Now we are proud to introduce the new Compass “Hirose Design” decaleurs. We offer one version to fit Compass and Grand Bois (and classic René Herse) stems and another for Nitto NP (Pearl) stems. We feel confident that these are the best decaleurs anywhere – a combination of the expertise and experience of René Herse and H. Hirose. And handlebar bags flying off bikes will be a thing of the past!

Click here for more information about Compass stems and 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.
This entry was posted in Racks/Bags, Stems. Bookmark the permalink.

29 Responses to Compass “Hirose Design” Decaleurs

  1. Matt Sallman says:

    Would the Nitto NP stem version also fit their Technomic stem?

  2. Stephen says:

    Arkel has made a locking handle bar bag for at least 10 years. It has never failed me and is very, very strong. You can see it at https://www.arkel-od.com/en/bike-handlebar-bag.html

    • Frank says:

      Nice, except the center of mass of the bag is rather high.

    • mattcoulshed says:

      The Arkel mount is envisioned as both support and handlebar stand-off, but as Frank points out it carries the bag high. It is also inherrently weaker and more likely to bounce due to the lack of direct support from underneath that you get on a front rack.

      I think that the handlebar clamps of the Arkel design have potential as a decaleur though, if they were matched with a bag attachment similar to the Herse design. This would give a functional if not particularly light or beautiful system that could fit on any bar or stem combination.

  3. cbratina says:

    The Berthoud bags you use are way too big for my purposes. When cycle touring, I use small front low rider panniers and a small Berthoud Mini 86 or larger 2086 bag on a Velo Orange rack to keep snacks, rain jacket, camera, passport, and wallet in the bag. It is easy to pull off when going into a museum or store and walk around for a couple hours. Two years ago I had a brainstorm and used elastic cord instead of the toe strap to hold the Mini 86 bag to the rack. With one finger I can pull the cord around the boss on each side from below. Don’t even have to look at it. Works great, holds it down well, and allows for quick removal and installation.

    Would greatly appreciate your coming up with a Klickfix type attachment for bags that aren’t large enough for a decaleur.

  4. Michael Kennedy says:

    Jan, is this decaleur safe to use with the 30mm drop kit?

  5. J L says:

    Will there be a provision to keep the new production decaleur from becoming filled with water? The Herse example suggests this was a concern. A U shape seems ideal for trapping rain when not in use.

  6. Magnus says:

    Does this work for taller riders, where the distance between rack and handlebar may be greater than average? I.e. is there any height adjustment? (Though noted – adjustability has its downsides, as you said!)

    • When using the version for Compass or Grand Bois stems, you can use a drop kit to lower the decaleur by up to 30 mm. Any more, and the lever arm of the bag just gets too big. In that case, we recommend a taller handlebar bag – custom-made, if necessary. Another consideration: If the bag is too low below the handlebars, it will be hard to access without dismounting the bike.

  7. I made my prongs twice as long as normal, haven’t had any problems with ejection. Although the pockets get in the way when removing it, minor annoyance. My other idea was to thread the bottom of the shaft and insert a thumb screw after it was installed but I haven’t needed to try that; I would probably lose the screw right away.
    This looks like a great solution!

  8. I would appreciate a drawing with measurements to be able to check if I can use the non height adjustable NP version on my bike/bag.
    Will it be possible to buy the parts separately? If you have more than one bike and but only one bag or the other way around.

    • It really depends on your bag, not the decaleur. Your bag should reach to the top of the handlebars… We use Berthoud bags and remove the stiffeners, which gives the bag a little “sag” so the bar height is less crucial.

      Unfortunately, the decaleur pieces still are matched pairs, so you’ll need one decaleur per bike. The bag part attaches to the bag with just two screws. If you really change bags often, you could use wingnuts on the inside, to make the decaleur easier to remove.

  9. Eric Burns says:

    I am planning to have an overnight biking trip, and was thinking how can I put my other stuffs. Thanks for such a very nice idea. I should add handlebar bag but I need to assemble my decaleur as well. Your post is such a big help bro. Thanks!

  10. Justin Hughes says:

    Has Compass considered offering their stems in an angle somewhere between 0 and -17d?

    • We’ve considered it. I prefer stems either to be horizontal or to match the angle of the top tube, if it’s sloping. But since all top tubes slope differently, the latter requires a custom stem. So we do ours horizontally… at least for now.

      • Justin Hughes says:

        Six degree sloped TT is fairly common for custom steel bikes, especially lugged ones. As is a 73 degree HTA. 11 degree stem (give or take a degree) would be a nice middle ground to please a lot of people. In the meantime I’ll have to stick with my Berthoud decaleur.

    • Bob says:

      Fairweather Cycles has a Nitto-made tall-stack stem that seems to have about 7-8° (UI-7), but it’s a faceplate design. I would be very interested in using that stem with the new Compass decaleur.

      • To use a Compass decaleur, the stem bolt must be vertical (or close)… I haven’t seen the Fairweather stem, but it probably won’t work with the decaleur. The Compass stem has enough built-in rise that it should work fine even for cyclists who want to get their handlebars higher.

  11. Have you published the results of the wind tunnel test of the bags? That seems to be very interesting.

  12. Keith Benefiel says:

    As an elder (not elderly) cyclist, I ride high, using a Nitto dirt drop, so I must use a decaleur that replaces a headset spacer. This is plenty strong enough with full support underneath the bag. My Swift has easy to deploy velcro straps on the bags bottom. What I want is a decaleur with an integral cable stop / adjusting barrel for canti or CP brakes. Put in a good word with Nitto? I’ll buy the first four. Most classic 1″ head stacks don’t have room for a hanger AND a decaleur. The hangers that clamp to the stem are inelegant. Style does count. Cheers

    • I am glad your decaleur works well. We’ve found that attaching decaleurs to a headset spacer doesn’t work well – the decaleur is too long and puts too much stress on the joint. I’ve seen a number of these break during rides on rough roads. There are solutions for very high handlebars, but they usually still mount to the stem. It’s the strongest solution.

      By the way, Compass components are designed by us. We develop them and make prototypes. Then we and Nitto test them, before Nitto manufactures them exclusively for us.

  13. Keith Benefiel says:

    Nice job of bounce-proofing. I would love to see/hear your solutions for high bars for us Medicare types. Our 35 year old Blackburn wrap-around-the-crown front racks carry the full weight of the Swift bags which are secured to the racks by velcro. All the decaleurs do is position the load. I agree it would be folly to weight a welded decaleur. For testing purposes, I’ll put our Wyoming back roads up against anyplace for sheer wickedness. Thus is the price of beauty. Cheers KB

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