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nice shop bike
Boulder Bicycle Lugged

Wednesday, August 5, 2009

Prototype Decaleur on Boulder Bicycle

A big issue is a lack of decaleur options for use with threadless stems. Here is one idea we've been tossing around. This one is a rather crude mock-up, but we've been testing it so far with good results. Essentially, we've taken a classic Rene Herse decaleur design, and modified it a tad.

The typical Herse decaleur attaches by the stem bolts to the underside of an Herse stem, with the bolts going vertically (perpendicular to the ground).

What we've done, is taken a "rejected" Herse decaleur, and brazed 1/4" tubes on top of the decaleur, filled in with an ugly fillet (this is a prototype, not something made by Mark Nobilette), and away we go. It attaches to the stem quite nicely. If we went with this design, we'd tweak it a bit for cosmetics and get some longer stainless bolts for mounting. And chrome it too (or powder coat if under the Boulder Bicycle name).

One downside, though, is that this results in a bag that is mounted pretty high. We could modify the bag attachment, or perhaps increase the drop of the decaleur, to use a smaller bag. So with the current arrangement, for a frame that is essentially like a 59cm, with an inch and a half of drop between saddle and bar tops, the necessary bag is a Berthoud 28.

So if this design has some appeal, let us know and maybe we'll run a batch. We probably would use a maker somewhere in Colorado for this, but probably not Mark Nobilette as he is so busy.


  1. why not just sandwich a piece of flat stock between the stem and the bar clamp, and braze the "U"-shaped parts of the decaleur onto that, slotting the ends of the U-shaped tubing to fit over the flat stock, like chainstays over dropouts.

    See also my homebrewed bag mount.

  2. It would be an option to more people if you dropped it down so that it is compatible with a wider range of bags.


  3. I agree with Jim Miller. With his comments made metal so as to give a secure fit, I'd almost certainly add a decaleur should my simmering interest in a Boulder 650B come to the boil, as in time it very possibly will.

    As powder coating on bag holding gear (in my limited experience) doesn't hold up well, I'd be more interested in a well done chrome plated version at a price to reflect the extra production cost.

  4. That's pretty much what I originally had in mind for my bike, but it looks like it's too high up and too far forward (I realize it's just a prototype).
    It seems like the cross pieces that connect the two sides of the "U" would interfere with the bag closing all the way. Maybe you could post a photo of one set up with a bag, to get a better idea how it works?
    Could you make them custom fit for a particular bike and bag?
    Here's what I made for my bike and a Berthoud 25:

  5. Hi folks,

    Mike here at Rene Herse Bicycles. Great comments. I think most of us are thinking along the same lines. I'll toss around ideas some more, maybe get another prototype up, and maybe we can get something into production. There really is a need! One thing, even the Rene Herse decaleurs can have the bag "jump" on a large bump. Berthoud uses a safety pin on their decaleurs. One could do that with an Herse or Singer decaleur and probably eliminate that problem.
    Mike K

  6. I think this is the ticket.
    I suspect that for production
    flat stock on the connectors for the two u shape pieces would
    be sufficient and involve less labor. A good fillet on flat bar should be more than sufficient.

    As to going lower, the lever moment
    on the clamp bolts is a potential issue.

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