Triple F Dropouts.

In my 20+ years of being a framebuilder there has always been one frame part that left me cold and that has been the rear dropouts. Over the years I’ve had the chance to design a few dropouts but time and budget always compromised the design. Well being on my own has allowed me to design the dropout I’ve always wanted, cost be damned.

Enter the “Triple F’ dropout. The name “Triple F’ stands for “Form Follows Function” and as you can see there is nothing extra or blingy about these dropouts. They are designed to be as minimalist as possible while still being strong enough for the largest rider to use the rest of their lives. The Triple F is machined from 4130 steel which is stronger and more fatigue resistant than most of the stainless dropouts on the market so the chance that one will ever break is almost nonexistent.

The simple design allows for the stays to be square cut on the ends and eliminates the need to slot the stays or give them a compound angle miter. This saves a huge amount of time. In my testing and prototyping I’ve found that I’m saving about 45 minutes per bike using the Triple F compared to a Breeze style dropout and even more when compared to a traditional plate style dropout.

There are two balls machined into the dropout for the stays to attach to and they allow for stays of different diameters and wall thicknesses to be joined to the dropout and almost any angle. This makes it simple to build most any sized frame and to attach curved stays if the builder wishes. The square cut ends of the stays mean that it’s quick and easy to get the stays to the exact right length – a few seconds on the disc sander is all it takes and there is no need to file a slot deeper into the stay to get the right length. The ball and socket interface also means that the builder can rotate the stay to the desired position on the dropout to get bent or ovalized stays to be in phase with one another.

Stays can be attached to the Triple F by either fillet brazing or TIG welding. When fillet brazing the heat is applied to the concave surface nearest the axle slot to preheat the ball and then brass can be pulled into the joint. The acute angle that the inside of the stay makes with the ball allows the builder to form a large internal fillet for strength and a small aesthetic fillet on the outside to blend the stay and the dropout together seamlessly.

The Triple F is also designed to be a ‘centerline” dropout – meaning that the axle lands the centerline of the chainstay. This means that the angle that the chain stay leaves the bottom bracket is true and that the stay will not be loaded into the BB socket at an angle. For anyone that has built lugged frames with Breeze dropouts this is a big deal.

I suppose many of you are wondering why I am sharing all this detail. It’s because as of today I am offering the Triple F to other insured framebuilders to use in their own frames. Because I’ve picked what must be one of the most complex shapes known to man to machine they aren’t cheap. But there is much time and frustration to be saved in using the Triple F and and I suspect that for many builders the cost will be more than worth it. The cost for a pair of Triple F’s is $110 plus shipping and they are only available to builders who can show proof of insurance. I have a one time offer to allow builders to try a single pair of Triple F’s at a lower cost of $85.

Interested builders should contact me by phone (800 605 5475) or email ( to ask questions or place orders.

These dropouts are the first in what I hope will be an ever expanding group of framebuilding parts for the discriminating professional builder. The first product was the brass barrel adjusters, now the Triple F rear dropouts and the matching Triple F front dropouts are next on the horizon.

Thanks for looking.


This entry was posted in Bike, Process.  

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9 responses to “Triple F Dropouts.”

  1. jim says:

    I’m not a builder but those are fantastic dropouts, Dave. Great work! Photo #4 really highlights their simplicity and design.

  2. Eric says:

    Lovely, of course:
    1. Will these go on all your bikes now?
    2. Can these handle braze-ons for fenders and racks?
    3. Idea for the holiday season: the FFF earrings ( . . . I’ve certainly seen worse).

  3. parris says:

    Hey Dave congrats on the design. Looking at the ball end of them they remind me almost of a ball and socket joint. Two things from the way the photos look it appears that there’s more surface area for brass to hold onto making for what’s potentially a stronger joint. And also would these tend to minimize possible stress risers in the chainstay/seatstay joint due to not having to cut into the tubes? I also like the way they look.

  4. Mike says:

    These dropouts look great and I hope they become available in a less expensive cast form.
    The shape also looks like a natural for adding integral fender / rack eyelets on a similiar “petal” form.

    It would be especially nice if the driveside eye was dished away from the cassette to allow a thin nut to be used and not interfere with the smallest cassette cog / chain.

    That can be for “down the road”. For now, these look really nice.

  5. kirks says:


    1) they will go on most bikes but not all. In some cases other dropouts will be a better choice. For instance I’m in the middle of a fully loaded touring bike right now and it’s best to build thoe with a long horizontal slotted dropout so the bike can be set up as a single speed if the derailleur fails in the middle of nowhere.
    2) mounts for racks and fenders can be added.
    3) the Triple F’s are pretty darn light but still might be a bit clunky for earrings……….. but who knows. Set some stones in them and see how they sell.


  6. kirks says:

    Hey PG,

    You nailed the core concept – ball and socket. It allows for most any angle to be made and a large surface area both inside and outside the tube for brazing.

    Thanks for reading.


  7. kirks says:


    Assuming that they work as as planned there will be cast versions but that will certainly be awhile any way you slice it. If/when they are cast it will be pretty simple to have gated molds made to allow for versions with rack eyelets cast in.

    Thanks for the comments,

  8. […] knows how long the Triple F is now available and ready to ship. See all the details on my blog – Kirk Frameworks Custom Bicycles – Blog Thanks for looking. Dave fff3.jpgfff5.jpgfff4.jpgfff2.jpgfff1.jpg D. Kirk Kirk Frameworks […]

  9. Dwight Kellams says:

    Any thought to incorporating a polished metal(stainless) for the contact point surfaces to avoid the worn/chipped/peeled paint look once the dropouts get some wear? I believe this is what the Ellis Signature dropouts have and that my 1989 Schwinn Paramount had as well.

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