Nautilus (Beached Bobber) - WBO 2018 Scratch Built

[tjwilson]

Steer Tube

Needed to lengthen the steer tube. In the process of lengthening I added a smaller dia tube that extends past the bottom of the steer tube for a headlight bracket mount.

I may make up a bracket that will bring the headlight closer to the head tube so that it will visually flow better into the top tube. Still trying to decide.

 

[tjwilson]

Top/Mid Tube and Bottom Tube Connection

Kind of hard to tell from these images. This is the non-drive side connection between the 2" top / middle tube and the 1" bottom tube. Could use a little more weld fill and smooth.

Wheelbase Adjustment

I put the frame in a fixture using the dimensions from the design drawing. As I started on the rear dropouts the wheelbase began to look a little long to me. I cut a disc out of cardboard the same size as the tire for a visual check. Ended up shortening the wheelbase by about two inches.

A little hard to see the difference in the images. If you look at the left edge of the cardboard "tire" you can see how originally it was off the edge of the fixture base and how far it moved forward.

Original Wheelbase

Shortened Wheelbase

Cantilever Tubes

This is the first build where I've used a triple tree fork. Didn't originally take into consideration the clearance required between the cantilever tubes and the fork tops when turning! I capped the cantilever fronts and then tweaked them a little to fit tight into the head tube. This helped gain some needed room for the forks.

Capping the Ends

Cupping the Cantilever Sides

Head Tube Cantilever Tube Connection

 

[tjwilson]

Rear Drop Outs

These are pretty heavy, not that the rest of the bike isn't

With this build I wanted to try to use stylistic traits from motorcycle design. Specifically bobber designs. The rear drop outs and the top tie rods came from this, attempting to give the rear a mechanical look. I also wanted to use this as an opportunity to try something that might look like a lugged frame connection. The drop outs are cut from 3/16" mild steel plate. 3/4" ID tubing was capped and then welded to the cut plates. 3/4" OD frame sections were then inserted into the drop out tubes and plug welded. My guess is the connection isn't as strong as a welded connection but, with the angles of the tubing and the tie rods the final strength of the rear section should be nearly the same. A guess anyway. A benefit from this approach was that it made these rear connections, that I always struggle with, much easier.

Top Tie Rods

Mock up to check final tie rod length and connections.

 

[tjwilson]

Frame Final Weld Up

 

[Dr. Tankenstein]

Oh yeah!


Sent from my iPhone using Tapatalk

 

[kingfish254]

You'll have a roller soon!

 

[tjwilson]

Frame Straightening

While working the 2" top/mid tube I lost track of the frame center line! This became real obvious when I got the frame sitting on wheels. With the image below I tried to show a good before and after. The seat tube was angled off to the non-drive side pretty bad. The rear axle was shifted to the drive side. Kind of amusing considering the earlier concern over noticing a 3/16" offset of the bottom bracket. The centerline offset of the seat tube and rear axle ended up being close to 3/4".

I took an eight foot piece of black tubing and inserted that into the seat tube. Using leverage and a strategically placed addition of 135 pounds (by jumping up and down on the frame), I managed to get the seat tube pretty straight relative to the main tube. The rear end was straightened using a 2x4 and applying leverage. Sheldon Brown has a good description of how to do that here:
https://www.sheldonbrown.com/frame-spacing.html

Overall I'm happy with how it now sits.

 

[tjwilson]

In-process Overview

Got a few in-process partially assembled shots in before the latest snow fall.

 

[tjwilson]

Fork Brace

Before I could get a good test ride in I needed to add a brace to the fork. I used mtb forks that I'd cut the brake bridge off of. I originally was thinking that bolting the front wheel in place would keep the fork ends from rotating. The front wheel itself wasn't enough so a brace was needed.

After the frame straightening and brace addition the ride feels comfortable. Didn't notice the bottom bracket offset but I did check and unconsciously I'd shift my foot out a little more on the left verses the right pedal. Nothing I'd be aware of unless I was looking for it though.

 

[léocwc]

 

[DeFresh]

Fantastic!!! Really enjoyable to watch come alive!!

 

[tjwilson]

Brakes

Was wondering if splitting center pull calipers and mounting them like cantilever brakes would work. Because the center pull calipers better reach around a wide tire mounted to a narrow rim and, mostly, they're what I have on hand. Didn't get a chance to try them on a test ride yet. Just pushing and applying the brakes tells me some adjustment to the way they're set-up will probably be needed. Maybe run the brake cable around a post or two on each side to better position the pulling force relative to the calipers?

 

[tjwilson]

Lights

I was pretty excited when the generator and lights from a $15 resale shop Breeze that I picked up still worked. I've wanted to do this ever since I saw a generator mount like it on this site years ago:
http://www.ratrodbikes.com/forum/index.php?threads/flying-pegasus.10458/page-2

 

[tjwilson]

Chain Guard

Had a cool chain guard but I felt it needed to be thinned up a bit from front to back. It has a really nice bead along the bottom edge that I wanted to keep. Rather than just trimming it off I sectioned the guard and welded it back together. After grinding the welds I used lead-less solder to smooth them out. The leading looks better than just the welds but not the greatest. Still learning.

The way that I had originally cut the mid / top tube looked awkward when the chain guard was mounted. I added a section to the tube to fill in that gap and make it look more intentional.

 

[tjwilson]

Fender

There were a couple mounting holes on the fender I used that needed to be filled. Took the opportunity to practice leading again. Still need more practice! Can't quite seem to get ride of all the pin holes. Far more difficult than plastic filler but I really like the look in raw metal.

Bending the fender brace from 1/4 solid rod.

Mounted Fender

 

[deven_science]

A very inspirational shape on your frame. Gives me ideas.

 

[tjwilson]

A very inspirational shape on your frame. Gives me ideas.

That's quite a compliment. Thank you.

 

[tjwilson]

Brake Modification

Added a couple of posts and re-routed the cable. The brakes actually work now!

Original Set-up

Post Pieces

New Set-up

 

[tjwilson]

Kickstand

The kickstand I wanted to use wouldn't stay tight and in place the first way it was mounted. I welded closed the slotted hole and bent the attachment end to better fit the chain stay tubing. A couple minor tweaks but it stays in place now.

Original Mount

Modified Mount

 

[tjwilson]

Handle Bars

I've been playing around a little with different bar options. Not really sure about the downward curved ones. Maybe if I was planning a mid-seventies type heavy flake paint? Guess I can wait till I have the frame finished to decide.