hpr-knowledge-base/hpr_transcripts/hpr3112.txt

Episode: 3112
Title: HPR3112: finishing the frame on the long wheelbase recumbent
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr3112/hpr3112.mp3
Transcribed: 2025-10-24 17:02:30

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This is Hacker Public Radio Episode 3, 112 for Tuesday 7 July 2020. Today's show is entitled,
Finishing the Frame on the Long Wheel Base Recombant
and is part of the series' bicycles. It is hosted by Brian in Ohio
and is about nine minutes long
and carries a clean flag. The summary is
an erated slide show of the next steps in building a bespoke recumbent bicycle.
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Hello Hacker Public Radio Brian in Ohio here. I'm out from under my rock
and I'm continuing the narration of building the recumbent bike using a D.A. Carson's plans
that are available at his website, recycledrecombants.org.
Specifically, I'm building the Mach 1 recumbent bike that he offers plans for
and I'm on page 3 and 4 of the plans.
Where I left off last time, episode 2962, I had the top half of the frame done
and now to finish off the frame, two assemblies had to be completed.
One is putting in a rear triangle and the rear triangle is the part on the bicycle
that is where the rear wheel fits and then connecting that rear triangle all the way up across the frame
to the front part of the assembly that was done a couple episodes ago.
So I didn't get any sound scape recordings from the garage this time.
I'll just describe, I've got some pictures in the show notes.
If you don't use the show notes, you're going to miss out.
Probably don't even want to listen to this one.
But if you like the show notes and you don't mind looking at some pictures, I'll describe what I did.
Let's get started.
So picture 1 shows the rear triangle assembly.
When you get done cutting up the frames, you end up with two rear triangles.
And luckily you do because even in the plans, Mr. Carson says that you'll probably mess up one
as you're trying to figure out how to bend this thing.
And he was right. I needed both of them to get it done.
So I followed his advice. I used the one that I thought was not going to work the first.
And then I, that gave me enough information and a good try at doing it.
And then I was able to get the second one done pretty well.
The picture here shows the rear triangle as jigged up in my trusty workmate, a tool that I highly recommend.
The picture 2 is just a close-up showing not only the way it's clamped in, but I went underneath the workmate table to actually get this to work.
It also shows the an old axle inside the frame there, which is good to show you where the wheel is going to go.
And he, Mr. Carson, recommends that you do that.
Put that axle in there when you're bending it up. But in the end, I didn't use it.
I found it to be kind of just in the way.
The last picture 3 shows the, just showed the front view of it being jigged up there in the workmate.
Picture 4. Okay, so then to actually do the bending, I had a piece of pipe and a brick.
And you've got to use something to get, to get a place, a fulcrum to bend those tubes down.
And what you're going to, what ends up, what you end up doing is heating up those pipes right where the pipe touch, where the tubes of the bicycle touch the pipe.
And then you bend that piece down when it's cherry hot.
And picture 5 there, you see the completed process.
And you'll notice no rear wheel in it and different colored frame because that's the red bike frame that I ended up using it.
But that's what it looks like when it's done being bent.
The discoloration, of course, is where all the paint got burned off.
And that's the completed process there.
And then take that piece and you have to braise it into the frame.
And so what I did was I used some long pieces of metal that I had laying around, one long piece down the long axis of the bicycle.
And then I put another piece of metal into the, where the axle of the wheel is going to fit.
And I used those to sight by going down to the far end of the bike and to the left and to the right.
I could sight to make sure that the frame, the rear triangle was square in the frame, perpendicular, basically really eyeballing it.
And honestly, it took a couple hours of fiddling to get this done right.
It's important. It's worth the time.
And it's pretty, I always find it amazing how you're, if you really take your time, you can really see square and parallel and perpendicular with your eyes.
It's pretty amazing.
So after it's all jigged up and clamped down, you braise the part in and that's picture seven.
It shows the rear triangle braised into the bike.
And so it's just braised in at the, at the, what is going to be the top of the bike, which is upside down right now.
And now those two tubes have to be connected with the, if you look at the very front of the bike where the front wheel would be,
there's two tubes from the original bike and you have to connect those two parts there.
And to do that, you use something called EMT. It's a mild steel tubing used for running conduit for electrical stuff.
And it's pretty, pretty, pretty easy to bend.
And so you use some of that material to connect those parts up and to tie the whole frame together.
And what you see in picture eight is the starting of that process, what you do is you cut a,
take a hacksaw and you cut a slot into the long axis of the EMT.
And then picture nine, you see it, you open it up, I used a piece of bar to open up the fish, it's not a fish mouth, to open up that EMT.
And you end up with, in picture 10, you see it open.
And then what you do is, in picture 11, oh, picture 11 shows the tool that you use to bend this pipe.
Now this first bend is pretty easy, it's just one kind of, it took about 10 degrees of bend or so to get it to match up with the tube.
You're just eyeballing it here and this is the first part of the bike that you're building.
Not using any bike components, it's completely custom to your parts that you have.
So again, you just take your time and get it to fit right.
And it's not super critical, but the better fits the easier it is to brace up.
Then in picture 12, you see all of those two components on the bike ready to be brazed up.
So you braze it at both ends of the pieces of frame and also the original down tube where the seat would go, which is now sticking straight up that blue pipe.
You braze it in there too. So you need to have good connections on all those.
Doing that completes the frame and basically you then just cut the top of that blue pipe to size so it's not hanging out there.
And just for orientation purposes, if you don't quite understand picture 12, the bikes upside down in the frame, in this workmate.
So it's upside down. You flip it over and the bike will be right side up.
That completes that part of the process. Not too difficult. Just take your time.
The hardest part was taking that getting the triangle square and perpendicular inside the frame there.
And it's worth taking a lot of time to do that.
The next parts that I have to build are the parts that connect the rider, the bike, the seat and the handlebars.
And so for the next show that we'll keep that for the next show.
Thanks for listening. It's Brian and Ohio signing off. Reminding everybody to go fast, take chances.
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