Acid. Reborn (finished)

[hbn]

Looks like any one of your mock ups is a winner, based on the voting! Your stem is probably a 21.1, which is why your headset isn't working either. I wonder what shipping is to Sweden from Minnesota? I might have one that would work really well on your build. And a headset, the old Schwinn ones are smaller in diameter.

View attachment 236018

This ^^^ !!! With maybe a smaller tank or metal piece that is suspended by the tabs, but with space around it so you 'see through' it, like your fork and the rest of the frame. Has a cool 'skeletal' look to it!

Great ideas, as usual
That’s really kind of you. Curious to see the stem you’re thinking of. Did Schwinn use 25x1.0 metric threading?

 

[hbn]

Today the angle grinder has been put to work. I got a hold of an old 21mm stem that fit. Problem was that it wasn’t a quill. So I took a 22mm quill lower, grounded it down to 21, and slant cut the stem lower.

…
Next, I’ve been testing ideas for rear wheel mounting and possibly rear suspension. The brackets used until now we’re good to get the wheel in the right location, but quite ugly.

This was one mock up. Lousy mechanics though, unless you go reverse (what was I thinking?) And honestly very ugly, not at all suitable to the look of the rest of the bike.
…
So I started playing with the idea of splitting the original 26” fork into two parts to widen it, making room for the wide rear tire. This idea stuck:

…
Angle grinder time. Fork split, holes drilled and tapped M8 to secure the halves to each other.

Too wide right now but figment is good though.
…
Mocked up again. More to my liking now

 

[OddJob]

I like the placement and use of the fork in the rear. Should help stabilize it and be plenty strong. How will you attach it to the frame? I assume the zip tie is just for mock up photos.

 

[The Renaissance Man]

Wow, I love the lines that you created with the fork! It extends the backbone of the frame all of the way from the headtube to the rear axel. Nice job!

 

[hbn]

I like the placement and use of the fork in the rear. Should help stabilize it and be plenty strong. How will you attach it to the frame? I assume the zip tie is just for mock up photos.

Plans are evolving, not sure yet but I’m getting closer

 

[hbn]

 

[hbn]

I've been considering different rear suspension designs that meet these criteria:

Appearance: Maintaining a smooth line from the top tube to the rear swing.

Functionality: Creating a strong, secure, and movable joint between two round tubes (fork steerer and seat tube) within the limited space.

Here are some ideas I've thought of:

Option 1: Using a high pivot by drilling through the steerer tube and attaching it to a square tube connected to the seat tube, with the bolt serving as the pivot axle.

-This option may not be very secure or durable.

Option 2: Adding a square section over the steerer to improve stability, as two square tubes would provide larger joining surfaces.

-However, it's difficult to find perfectly fitting square tubing in two different sizes.

Option 3: Incorporating the upper half of a cylindrical strut over the steerer and utilizing its bushing as the joint.

-Unfortunately, there isn't enough space, and this option would add significant weight.

Option 4: Attaching a stem to the steerer to lower the pivot and create more space, reducing the pedal kick when the rear suspension compresses.

-However, lowering the pivot would cause the swing to move forward when activating the suspension, which is not feasible due to space constraints.

Now, let me share my solution. My father-in-law had a compact and sturdy scissor jack. Yes, had. I cut it into pieces and modified the steerer and the jack to fit together.

Stable and compact joints

Let’s mix and match

 

[OddJob]

Now the real question is, after you cut up his scissor jack, do you still have a father-in-law?

The fit is really good! I'd like to see a video showing the 'arc' or movement it provides as suspension. Curious how much and smoothly it moves.

Very ingenious design!

 

[hbn]

Now the real question is, after you cut up his scissor jack, do you still have a father-in-law?

The fit is really good! I'd like to see a video showing the 'arc' or movement it provides as suspension. Curious how much and smoothly it moves.

Very ingenious design!

Hahaha! He just shakes his head (he’s used to my ideas). I promised to get him a new one. Good idea with the video. Hopefully I can finalize the swing and make a video during the week.

 

[hbn]

Friends, the swing is in place!

The fork legs are still way too long, I didn't want to cut them until the swing was in its final position.

I ground flat surfaces on the steerer to 1.) get it to fit into its square collar, and 2.) to help counteract unwanted longitudinal axis rotation.
To get the steerer as far towards the swing axle as possible, I ground notches in its top that causes it to lock into position when weight is applied to the swing.

An inner leg part from the jack is used as the underside of the collar, as it provides a good fit with minimal work.

All parts fit so snug that they stay together without any screws. The only motion I need to block with a screw is in the opposite direction to what weight on the wheels exerts. Hence the screw through the existing hole in the fork doesn’t bear any weight, and all the parts are locked together.

To secure the swing assembly to the seat tube, I use exhaust clamps.

Here is a video of the swing in action

 

[OddJob]

Very cool! I see the sketch up but not a video?

 

[hbn]

Very cool! I see the sketch up but not a video?

I didn’t expect you to be that fast!
Wrote the text on the laptop and added photos from the phone afterwards

 

[hbn]

As the rust is getting more intense by the day, I’m rethinking my choice for color/patina and would like your opinions.

Light rust, almost a golden brown

Intense rust

Blue (and rust)

Green (and rust)

Raw

What do you think?

 

[GeePig]

Rust is good...

 

[BobbyStillz]

As the rust is getting more intense by the day, I’m rethinking my choice for color/patina and would like your opinions.

Light rust, almost a golden brown
View attachment 237982

Intense rust
View attachment 237983

Blue (and rust)
View attachment 237984

Green (and rust)
View attachment 237985

Raw
View attachment 237986


What do you think?

If you can match that blue, then I vote blue and rust.

 

[Captain Awesome]

As the rust is getting more intense by the day, I’m rethinking my choice for color/patina and would like your opinions.

Light rust, almost a golden brown
View attachment 237982

Intense rust
View attachment 237983

Blue (and rust)
View attachment 237984

Green (and rust)
View attachment 237985

Raw
View attachment 237986


What do you think?

https://ratrodbikes.com/threads/color-rust-choice-for-my-build.118583/#post-1255463
Vote here!

 

[OddJob]

I like this one....

 

[hbn]

Some progress.
To further secure the swing, I’ve added an inner rod (red one).

The red rod has a perpendicular slot for the axle. When it’s in place, the yellow fork is slid forward, to engage the axle with its longitudinal slot.

All parts are locked by an M8 screw. The hole through the inner red rod is tapped with an M8 thread, to lock it all together with one screw.

 

[hbn]

Further. Swing is finally secured. Upper part of fork legs are somewhat oval in transversal direction and lower legs are oval in longitudinal direction.

-Why is this interesting or relevant?

-Because that means it is only possible to slide lowers into uppers when lowers are rotated 90-degrees. And when they are at their final position they are rotated to lock in place.

Fork legs measured, cut, drilled, tapped M5 and screwed to secure them.

 

[OddJob]

Wow! You have really gone down the engineering rabbit hole on this one!

That's some pretty tight clearance, Clarence....

You've got a 29 x 3.0 tire on a wide rim, I'm surprised it even fits at all without a special fork. Once you get it dialed in , I'm dying to see the rear susp in motion!