Rigid Girder (boardtracker style) fork build for a bike build later

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Hi guys,

In between the busy / racket life right now, I still need my relaxation in building things.

A while ago I cut a 1" city bicycle fork in pieces. I used the headtube shaft for another build. Them beautiful legs tough... :whew:

I stored the fork legs in my shed, still with a part of the crown attached. It is nice to see that these mass produced forks are brazed.

Now I have some ideas for my Electra Ratrod bike (stay with me here):
(pictures below)
  • Use the steel oldschool rims and powdercoat or paint them. I love these rims, they have this rugged look!
  • Swap the frame for a Ruff Porucho boardtracker frame.
  • 3.0" tires with early 1900's looks.
  • Build a 1" threaded fork with the rigid boardtracker bike fork looks. I am aware that the Ruff Porucho frame is 1 1/8".
  • Goal is to build a nice sturdy fork that is not too heavy and still fits the frame tubing sizes.
  • No engine!
Some things I am considering, so opinions/suggestions are welcome here:

Already measured a heck of a lot of stuff and made some 3D models. Now working on the assembly so that I can lasercut the plating.
Tubing will be CroMo tubing.
Explanation on the top plate fork gap: The hole is bigger than the fork shaft, because there will be a solution designed there: I need to 'tighten and adjust' the headtube bearing without putting tension on the plate. So the plate gets a clamping bracket and there will be a bush between the top bearing cover and the locknut.
So when there is a little play in the headtube bearing: Loosen the top clamp a bit, loosen the top nut, tighten the bearing cup and re-tighten previous parts. If there is more explanation or a drawing needed, let me know! :cool:

Pictures: (first the Electra bike, then parts and models and inspiration final).

Enjoy and let me know what you think!

4mWjBU9.jpeg

4AfHqVn.jpeg

khjEiho.jpeg

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hHOTCzl.jpeg

Kh8g3EW.jpeg

lsm8nO7.jpeg

LNkCGWi.jpeg


6qd4uJM.jpeg

TgyN6lL.jpeg


Final pictures: inspiration!
 
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Good plan!
I'd go for red color. 346 tires since i believe those straight grooves look way more oldschool in real life then Cruzo ones. And you can totally put one of those old huge racks without spoiling the looks of the bike and not compromising on functionality! I was sure i'd be able to find one quickly, but to my surprise i hadn't. Even though i saw many bikes like that back in the days in NL. I am talking about your classic opafiets, with the black license plate and the pump tube on the rack.
Talking about the light, nothing beats the carbide lamp for the looks you are going for!
Снимок экрана 2021-10-05 в 22.52.00.png
 
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I like the drawings, and I need a similar gap for the fork mod I am working on. :)
Thanks GeePig!
This is my current idea, maybe you can use it too.
Use a 'car' exhaust clamp: (I got a 28mm and a 36mm one).
Why?
Well, milling, casting and bending round objects is a bit more expensive. And I do not want to 3D print for this project (3D printing is not there yet, strength/toughness wise).
The plated part can be drilled and bolted on there aswel. There is space for a smaller countersunk screw.

It cost me 1,55 euros + it is steel, so I can weld it on the top plate + simple + light.

When painted this clamp will fit the rugged, purpose built looks I guess.
Important note: There will be a bush inside the clamp, I do not want to damage the fork threads.

gZwM5xZ.jpeg


Good plan!
I'd go for red color. 346 tires since i believe those straight grooves look way more oldschool in real life then Cruzo ones. And you can totally put one of those old huge racks without spoiling the looks of the bike and not compromising on functionality! I was sure i'd be able to find one quickly, but to my surprise i hadn't. Even though i saw many bikes like that back in the days in NL. I am talking about your classic opafiets, with the black license plate and the pump tube on the rack.
Talking about the light, nothing beats the carbide lamp for the looks you are going for!
View attachment 174888

:inlove: I love your thoughts @Starnger, I already ordered a 1910's brass carbide lamp a couple of days ago!

Thanks for your advice on the tires, I love the straight groove tires! Never seen them for real though...

And I feel you regarding the rear rack! Kronan racks are really nice.
I can give you a great website then: (also rare American bike parts for sale sometimes). And checkout their Klunker in the US bike section. I am drooling for years on this website. Due to time issues, I never visited them unfortunately. Have fun! (link below).
Bikes To Remember

Alright, some more pictures and sketches from this build process:

4DRbXSc.jpeg

DGsl5Ff.jpeg

Early clamp idea. Mold of die for a press needed. Milling/lasercutting is an option......
x41LYeG.jpeg

WarSQOv.jpeg

heSigzf.jpeg

Offset measurements.
 
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Thanks GeePig!
This is my current idea, maybe you can use it too.
Use a 'car' exhaust clamp: (I got a 28mm and a 36mm one).
Why?
Well, milling, casting and bending round objects is a bit more expensive. And I do not want to 3D print for this project.

It cost me 1,55 euros + it is steel, so I can weld it on the top plate + simple + light.

When painted this clamp will fit the rugged, purpose built looks I guess.
Important note: There will be a bush inside the clamp, I do not want to damage the fork threads.

gZwM5xZ.jpeg
That is an excellent idea, and cheap is always a good thing in my book :)

As it happens, I need to remove a steel fence post made of U section steel, which I plan to cut to size then chain drill and file out to get the right size holes. My sticking point at the moment is finding something suitable to use as a bush - rugged enough to take the loads but easy enough for me to prepare.
 
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That is an excellent idea, and cheap is always a good thing in my book :)

As it happens, I need to remove a steel fence post made of U section steel, which I plan to cut to size then chain drill and file out to get the right size holes. My sticking point at the moment is finding something suitable to use as a bush - rugged enough to take the loads but easy enough for me to prepare.
Checkout for adapters: 1 inch to 1 1/8 inch for fork and/or headset frame tube. What diameters and length do you need?
If you find a tube, you can cut it and file it by hand on a vice, so it is nice and straight/angular.
Also rollcage tubing shops (CroMo) are a good one. Very tough material, not always easy to mill.
 
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Checkout for adapters: 1 inch to 1 1/8 inch for fork and/or headset frame tube. What diameters and length do you need?
If you find a tube, you can cut it and file it by hand on a vice, so it is nice and straight/angular.
Also rollcage tubing shops (CroMo) are a good one. Very tough material, not always easy to mill.
I am not sure about the size yet, I still need to figure out which fork is going to be the best choice to use in the headstock.
My constraints on material are first to check out what is lying around in our barns, and then if that fails to try the local DIY and tool shops, of which there are few around as this is rural Eastern Poland. If that does not turn up anything then I look for an alternative solution.
 
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Quick model update:

xdPQS1u.jpeg

The bush, just under the top nut is not modelled here. Not necessary.

QYNv3Kq.jpeg


KWw431c.jpeg


Should anything change? Did I miss anything? :bandit:

An eyelet to attach a bracket for a lamp could be a good idea.
You can see how the exhaust clamp is used too.

I thought about a handlebar clamp just above the fork tubes (like the Harley boardtracker picture), but I am going to use a standard "oldschool" stem for 1" threaded forks. The handlebar clamp is still possible/optional in this design. I like a little bit of flexibility ;)

Friday or Monday I will order the lasercut parts.

Then I'll make a drawing for welding etcetera.

Fun fact: In this 3D assembly, the weight of the fork (with headtube, bearings, everything) is 2.5 kilograms or 5,51 pound.
 
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Just an idea, now that I can see the whole thing, how about losing the exhaust bracket and having a steel tube-like spacer. So you have the top headset nut, the steel tabbed washer on top of that, the spacer tube to run through your top bracket, and then the top nut tightening down on that? The tube spacer would be long enough and just snug enough on the top bracket to allow bearing adjustment without chaffing/rattling? Or sleeve the outside of the steel spacer tube with a nylon bush?

My design will certainly need some compliance up at the top because I will be tying together two forks, one with suspension:

AM-JKLXvnKfTXt7aAxH1X0Hoy7zF0XQvfHgj-0dQtEH5nExMID6Z5QMLvqj-U5bzRrZEbSe0AU5P1oc8z_JDX7Kw7v6iwQH5cYfegGCZVB7J_1SjVETdg9br5Iw9IuDY4PthXoyIsHJ_Z4qExhVdj0fR2Y4f0Q=w1249-h955-no
 

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A month ago I went to the start of the border to border rally for motorcycles 100+ years old. All the guys had white beards, the gals were young. There was one young man, probably under 40, that was riding a Board tracker. Man, 2000 miles. He had bicycle lights and the rig was in class 1, no clutch, transmission or gears, gas and go they called it. I didn’t get a picture because he always appeared from nowhere screaming around, even in town. He seemed like he was bored with the preliminaries and wanted the rally to start. His riding position was modified a little as he could rest his elbows on his knees, but still. The bike was pretty small, all engine. He was having a blast, you could see the ear to ear grin. Here is a photo. I would recommend his position for comfort and for the better forward view. It still had the classic look. 90 antique motorcycles took part.
35982BC6-E2BD-4233-96E9-6FF2DCEB6160.jpeg
 
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Just an idea, now that I can see the whole thing, how about losing the exhaust bracket and having a steel tube-like spacer. So you have the top headset nut, the steel tabbed washer on top of that, the spacer tube to run through your top bracket, and then the top nut tightening down on that? The tube spacer would be long enough and just snug enough on the top bracket to allow bearing adjustment without chaffing/rattling? Or sleeve the outside of the steel spacer tube with a nylon bush?

My design will certainly need some compliance up at the top because I will be tying together two forks, one with suspension:

AM-JKLXvnKfTXt7aAxH1X0Hoy7zF0XQvfHgj-0dQtEH5nExMID6Z5QMLvqj-U5bzRrZEbSe0AU5P1oc8z_JDX7Kw7v6iwQH5cYfegGCZVB7J_1SjVETdg9br5Iw9IuDY4PthXoyIsHJ_Z4qExhVdj0fR2Y4f0Q=w1249-h955-no

I appreciate your thougts! But do not understand the whole idea. Maybe you can sketch your idea?

You could use a 1" seatpost clamp as a top hinge (where your headtubes come together).


Thanks @kingfish254 and @GuitarlCarl !


A month ago I went to the start of the border to border rally for motorcycles 100+ years old. All the guys had white beards, the gals were young. There was one young man, probably under 40, that was riding a Board tracker. Man, 2000 miles. He had bicycle lights and the rig was in class 1, no clutch, transmission or gears, gas and go they called it. I didn’t get a picture because he always appeared from nowhere screaming around, even in town. He seemed like he was bored with the preliminaries and wanted the rally to start. His riding position was modified a little as he could rest his elbows on his knees, but still. The bike was pretty small, all engine. He was having a blast, you could see the ear to ear grin. Here is a photo. I would recommend his position for comfort and for the better forward view. It still had the classic look. 90 antique motorcycles took part.View attachment 175062

Awesome story. I enjoyed that, thank you!
I already mentioned it many times before, but I have a certain weak spot for people who do things their way and/or differently. I can't really describe what it is, but taking this story as an example: This guy having fun on a old machine makes me grin aswel. A bit of hardship, a bit of a wildcard in doing things makes you appreciate it I guess. And I really enjoy this forum for the people doing things their way.

UPDATE

I ordered a "RUFF CYCLES PORUCHO" frame. Could not help myself.

I ordered the lasercut parts for this fork.

This weekend, I ripped the lug's of the old fork with heat and some pliers.

Specific comments under the pictures.

U5rOOAv.jpeg

Double checking the fork length! This is a 26" wheel, 50mm wide steel rim and 26x2.35 tires. 3 inch tires must fit!

YmEBPHm.jpeg

I do love filing, but not if there's hours and millimeters to remove... So I grabbed some pliers and a heater to tear of the lugs (old fork crown).

gi6t4Fi.jpeg

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Filed it a bit more.

Filing to fit the lasercut triple trees will be done when the plates are here.

Next: Make a drawing with measurements. Think about a welding JIG. And handcut the tubes to the right size.
 
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Update:

I made some sketches for a fork-welding-JIG. Looked for parts in my parts bin, but could not find everything I needed.
Most frame and fork building JIG's are made of extruded aluminum profiles. So eventually found a shop where I ordered some bit and pieces.

XagEw6C.jpeg

1 inch fork tube, some wedges and my steel beam. Not using this unfortunately.

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Picture above: Fork JIG inspiration picture. My JIG will be a little bit different.

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Colouring page (for the fans! :grin: )

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Fork length and tube sizing in milimeters.

Some thoughts I would like to share:
I have a Shimano CB-E110 hub left. I can use this hub as a drum/coasterbrake front hub. The wide nut on the coasterbrake-arm side could be shortened a bit to fit the 110mm hub there.
Does this make the (already reliable) bicycle even more reliable? Being able to swap the front/rear wheels? :bigsmile:

I do not know anything about the thickness/diameter of the "Ruff Cycles Porucho" tubing, so I hope this fork fits the design a bit. The fork is not as fat as some "large diameter" triple tree forks that are used for this frame.
If it does not fit the looks, I can always build a fatter fork with my fork building JIG.


Thanks for reading, liking and tips as always!
 
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Where should I submit them for judging when finished?
You can submit here.
This gives me an idea for a Ratrodbikes competition: Best bicycle concept sketch :cool:

Ok, back to the build:

I decided to purchase parts for a "fork welding jig". Considering I am always building something, a jig is handy.

These are standardized aluminum extruded bits. Aluminum is very stiff.
The idea is that the most important bits (the headtube shaft and the front axle) are a perfect 90 degree angle and the right offset when welding. And after welding :chicken:


bfMTZer.jpeg

AL7hYWU.jpeg

t9ZaTJX.jpeg

I used the extra angular bits in the middle because they allow less play in the upward facing profile.

SyeWwI6.jpeg

The fork shaft is lying on some wedges the fit perfectly in between the angular profiles. The wedges keep the shaft perfectly aligned.
With help of the (now unused) long bolts I will press/clamp the shaft down to keep it in the desired position.
Maybe I will tap some M10x1 threads in the 'angular profiles' unused holes, to clamp the wedges even more... don't know if that is necessary... :39:

uNxj3U2.jpeg

The complete setup.
Note: The top screws (left in the jig/picture) are countersunk screws. This allows more space for the fork axle and the clamping nuts.


So this is my working plan: (I am open to other ideas/suggestions)
  1. Press the fork crown base on the fork shaft.
  2. Press the fork crown plates on the crown base.
  3. Align + clamp down the fork shaft.
  4. Press/tap the fork legs in the crown plates (oval holes).
  5. Align + clamp the fork axle with the legs.
  6. Weld the shaft + crown + fork legs.
  7. Remove? Or keep? The welded pieces in the jig.
  8. Then add and weld the rest (truss pieces) to the fork base.

More (luxury) choices regarding the fork:
  • Solder the fork (oldschool and I love the looks)
  • TIG weld (the Porucho frame is also TIG welded I am guessing)
  • MIG/MAG weld the fork.
 
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Almost forgot:

Lets talk paint and colours!

I am just going to type my thought process here:

As predicted, not looking for the perfect finish here. I have a big soft spot for "functional art" and old crafts.

I saw and read this build:
Rusty boardtracker inspired build!

The rusty antique looks are just gorgeous :inlove:
But I ride my bikes a lot and am not always looking for rusty smudges on my clothing.

How to get that antique looks without staining my clothes?
I am thinking painting with a brush, not a spray can.

But which colour with old looks?

I have a soft spot for "RAL 4007". It has the antique vibes... :39:
016ral4007-036.jpg


Other ideas:
RAL 8012 (redbrown)

RAL 8017 (chocolate brown)


More inspiration:
WorkCycles-Fr8-Commute-Daredevil_3-1400x1287.jpeg

I like the red rims with the dark red frame.

Henderson-Board-Track-Racer-11.jpeg

I never thought of blue. I like it with the black frame.


I do like the dark red Indian boardtracker colours.

Mustard brown/green/yellow:
csm_b3afdc3b061a266f4c9e81aa38617011_ecc04b2f22.jpg



I don't know yet, preferences from your side or nice ideas?
 
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@OddJob is the patina master. He has a technique with spray paint to simulate rust.

"Spray a few spots of Cinnamon and Dark Taupe where you want rust to be. Cover those spots with mustard so that will wash off with the top coat after it's applied and reveal the 'surreal rust'."

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Photo examples are on plastic
 
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