11
Dec
13

The Fork-a-lizer

Oh the brain cells are constantly engaged over here in the Bike Bunker, always thinking up better and more entertaining ways to wrestle tubing into the shape of a bicycle.

Case in point: the Fork-a-lizer, the latest, greatest, and most elegant method for copying the geometry of a bicycle fork ever conceived by a shade-tree mechanic. Personally, I ascribe this particular flash of Near Genius to the fact that I got a tetanus shot this week. Strengthens the corpuscles in the brain while rendering one impervious to the maladies of the metalworker, such as the dreaded lockjaw.

Now you may ask yourself “Copy the geometry of a bicycle fork!? Why would anyone ever want a tool to do that?” The answer to that infinitely rational line of questioning is rather prosaic: I don’t have the tools, time or the training that is necessary to come up with The Next Great Thing in bicycle fork design. Sure, down the road it may make sense to play around a bit, but for now simply copying a design that I know will work is both expedient and, when you are laying out your own cash for tubes and fork crowns, economical. Plus, with a grand total of two bikes under my belt and a third one now underway, it’s not like I am Richard Sachs or Irio Tommasini. I’m just an idiot who builds bikes in his garage. A deliriously happy idiot, but an idiot nonetheless.

Hence, the need for the Fork-a-lizer.

The concept behind the Fork-a-lizer is relatively simple; it is an adjustable jig that you can set up to produce a straight legged fork that matches the specs (height, rake) of fork that you wish to copy. You pop in the fork that you wish to copy (1 inch steerer tube for now) adjust the two set screws under the steering tube so that the tube rests upon both of them, and line up the brake hole in the crown with the adjustable pin that sticks up from the Fork-a-lizer body. Those are the settings. Now you remove the fork that you are copying, pop in the steering tube and crown of the fork that you are building, line up the brake hole in the crown with the adjustable pin, cut the fork legs to the proper length, and you are ready to rock.

Bonus feature: the finish on the Fork-a-lizer is heat resistant (i.e.. I had a can of barbecue paint laying around).

A couple of caveats. The “adjustable locating pin” is only sort of adjustable. I have it located so that it makes a fork with a axle-to-brake-hole height that works with short reach road brakes. If I was going to make a touring bike and wanted a fork that would fit fenders or clear fatter tires, I would need to move the pin to create more clearance. I made the pin removable if I wanted to make a fork with more clearance. I have some ideas on how to deal with this on the Mark II version of the Fork-a-lizer.

Does it work? Damn straight it does. It makes the pretty girl very happy.

The Fork-A-Lizer, now available in fire-resistent black.

I still haven't cleaned my workbench.

In warm weather that helmet smells like a dead animal.

I have a lot of C-Clamps laying around my shop.

Voila!

Those are some damn fine joints.

Flowers!

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11 Responses to “The Fork-a-lizer”


  1. 1 EverydayRide
    December 28, 2013 at 8:26 pm

    “Crap on my Work Bench” LOL ….Craftsman!!!!! Great write up. I like everyone of your write-ups. Your bikes come out splendid in each case [love the orange one bestest]. Seeing a one inch steering tube in a bench vise is always gut-wrenching, but I like your brake locating pin concept.

    Great work as always!!!!

    • 2 Anonymous
      December 28, 2013 at 11:41 pm

      Hey, thanks for reading! I’m glad that there is some kindred soul out there who finds this stuff interesting.

      Number 3 is turning out to be a rather interesting bike. Santa was pretty nice in terms of tools and bike parts – who knew that he had a “thing” for NOS Shimano 600 and bolt on front derailleurs? Classy guy.

      And don’t lose any sleep over my clamping the steering tube in the vice – no forks where harmed in the making of this blog post. I made some aluminium covers for the jaws, and the jaws are just tight enough to have the thing stand upright. As opposed to the author, who is usually too tight to stand upright…

      Greg

  2. 3 Anonymous
    February 4, 2014 at 6:28 pm

    Hi there – I’m a little confused by the fork-a-lizer. Isn’t your rake fairly pre-set if you’re using straight legs and an angled crown? I’m definitely considering doing a fork for #3 (#’s 1 and 2 were both aftermarket forks).

    Are the “stops for the steerer tube” just to set the steerer up off of the jig a fixed distance?

    Fork looks beautiful!

    • 4 Jonathan
      February 4, 2014 at 6:28 pm

      Sorry, didn’t mean to make that anonymous

    • February 4, 2014 at 8:19 pm

      Hey Jonathan –

      You are correct that the “rake is fairly pre-set if you’re using straight legs and an angled crown.” The crown is angled at 7 degrees, so you are only going to be able to tweak it a little bit. You only want so much slop in crown sockets. That said, I was able to tweak it to around 8 degrees if I wanted.

      You are also correct that the “stops for the steerer tube” are there to lift the up at a fixed distance. They are also there to set the angle of the steering tube as well. I made the two stops on the Fork-A-Lizer adjustable so that I could do a couple of things. I wanted to be able to check both rake and leg length (i.e, the distance between the brake hole and the axle). To match the crown height, the jig was built so that, if the legs are the correct length, the the brake hole in the crown lines up with the indicator bolt that is sticking up. This gives the leg length/crown height that I was shooting for. I then adjust the two stops so that they both touch the steerer tube. All things being equal, if you put your project fork in the jig, and if the steering tube hits both of the stops, and the indicator lines up with the brake hole in the crown, and the legs are cut to a length where the fork ends hook into the axle, then you have a fork with the same rake and same working height as the one that you copied.

      Hope that this helps – and let me know how the fork and frame turn out! I’m about 2/3 done with Frame No. 3 – the fork and front triangle are done; now it is time to futz with chainstays…

      EDIT – I forgot to mention, I used the jig to determine where to cut the fork legs. It was easy – I had already brazed the steering tube into the fork crown and drilled the brake hole. So what I did was use the aftermarket fork to set the stops, insert the steering tube and crown into the jig, take the two loose fork ends and clamp them into the axle on the jig, and then measure the distance between the fork end and where the leg seats in the socket. Voila!

  3. 8 Jonathan
    February 5, 2014 at 2:05 pm

    They’re both Columbus Zona (first one I used Nova lugs, 2nd one I used Sachs lugs). Both rattle can paint (1st one from the local auto store – which isn’t holding up well, 2nd one I bought high quality automotive paint in spray cans on the internet and it’s doing fairly well thus far).

    • February 6, 2014 at 2:44 pm

      Out of curiosity, what brand automotive paint isn’t holding up well? Is it Duplicolor? I’ve never had luck with their rattle cans. That said, they do have an interesting pre-mixed spray lacquer that might induce me to fire up the compressor and get out the paint guns. Burnt Orange Metallic with white for the head tube. Ditto the white for the panels for the decals on the downtube and seat tube. Maybe red trim in the “windows” on the fork and lugs.

      • 10 Jonathan
        February 6, 2014 at 8:51 pm

        The orange bike is duplicolor engine enamel. It chips fairly easily. Thankfully, the primer I used seems to be on there really well, so I rarely chip through that. Adding insult to injury, the high quality 2k clear coat didn’t adhere too well to the crappy spraypaint, and has peeled off in a few places. Too bad, it looked so shiny and beautiful to begin with. I got my spray cans for the 2nd bike here: http://www.coastairbrush.com/categories.asp?cat=819

        These are pretty awesome, because they’re pre-reduced, high quality paint. Spent about $130 or so on the paint from here including primer/2 colors (3 total cans of color)/Clear. It’s holding up pretty well and the quality is decent. Got some orange peel, and it’s certainly not pro caliber, but for what I spent it’s not bad. Got a nice shiny, sparkly sheen to it.

      • February 7, 2014 at 2:17 pm

        Thanks for the info. The “House of Kolor” paint is supposed to be pretty cool. Nice colors. Another source that I am looking at is “Lil’ Daddy” Roth. His dad, Rat Fink Ed Roth, was a noted car customizer in the 1960s. I’ve never used this, but it looks pretty good. They also push compatible primers, prep, etc. They are very clear that Rustoleum primer won’t work as it is oil based. Roth’s stuff is apparently urethane. (If anyone reading this has used the Roth paint, what’s your experience been?)


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