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-   -   PVC Pipe for frame? (https://www.bikeforums.net/showthread.php?t=1225193)

squirtdad 03-15-21 04:02 PM


Originally Posted by MrInitialMan (Post 21965060)
I was thinking about how to best answer this, thus the delay in replying.

I was looking at this for ideas, not necessarily to directly copy.

My goals are, and have always been:

1) Must be stable. Yes, recumbent trikes are stable, HOWEVER:

2) Ingress and Egress must be reasonably easy. By the time a recumbent trike is low enough to be stable, it's so low that, with the baking show's worth of lard padding my seat, it's hard to get out of. Some trikes I almost had to roll off the seat onto my hands and knees, then get up. Therefore...

1a) Must be stable with a relatively high center of gravity.

3) Must provide some protection from weather.

4) Must have a smooth ride. Honestly, fat tires looked tempting, until I found out how squishy they are. I've ridden on half-flat tires before. No fun. Thus the suspension.

5) Be COMFY. Which is why I wanted to go the recumbent route in the first place.

6) Be nice to look at... and I kind of like the look of old cars, on which my original design was VERY loosely based.

7) Must have decent carrying capacity, including room for saxophone or guitar, or groceries.

Here are my thoughts for you, many are probably repeats from before, I would truly like to see you succeed, but to do that you may need to make choices and remember KISS (Keep it Simple Silly)

Bottom line is you really want something you can use, otherwise why it is just an art project, nothing wring with art projects per se, but I understand you goal is to have something you can and will use

weight is critical, if you build something that weighs 145 kilos and then add a 100 kilos of person and 25 kilos of stuff, it will be slow, hard to get up hills and dangerous coming down hill. Every little feature adds weight, you would have to be ruthless in this area

There always constraints, weight, cost, material, time, skills, knowledge, experience. If you had a full on carbon fiber faclities and engineers and $100k budget you might be able to build what you want and it still work, otherwise building in the barn with steel tube, etc it is going to be harder and you will have to compromise

Not all recumbents are low....see some pics later

stable and high center of gravity oppose each other in physics

the economic concept of TANSTAAFL (there ain't no such thing as a free lunch) applies to everything you , I.e. you make a very weather proof enclosure out of 1/4 " ply wood....cook but adds weight and look out for the headwinds

best for weather is proper clothing

I would suggest you think more bike and trailer to get what your are looking at

A higher seat 3 wheeler like this has suspension and with 2 wheels in back you probably you can use some of what you already have gives you a lot of what your are looking for. you could set up some weather protection with fiber glass poles (think backpacking tent poles) fabric and clear sail material (think windsurfing sails as a material example) you can get plans and it does not look like a hugely complicated build https://www.atomiczombie.com/timberw...rike-diy-plan/

https://cimg9.ibsrv.net/gimg/bikefor...f8f924650d.png

and for more haulage a trailer

https://cimg7.ibsrv.net/gimg/bikefor...1569e4ec96.png
https://cimg9.ibsrv.net/gimg/bikefor...01e3800ea7.png


some things out there for inspiration

https://cimg3.ibsrv.net/gimg/bikefor...ddd947437d.png
https://cimg4.ibsrv.net/gimg/bikefor...0a4eb23935.png

MrInitialMan 03-17-21 04:38 AM

Been thinking about this. I think I will forgo the floor I originally had in mind. I'll just have to either learn to avoid puddles, or have just a partial floor that ends before the pedals (A thin sheet of plastic--like a snow carpet--should protect me from splashes from below.)

Also, going to see about getting some materials of my own--and maybe a pickup truck to transport them in. The steel I originally used was waaaaaaay too thick.

The suspension of the trike looks interesting, and while I'm still wanting front suspension, I ran across Sliding Pole suspension, which is where the poles the front spindles turn on are elongated to include coil springs. Should be reasonably light and simple.


The reason I was looking at these PVC plans is, well, I don't know how to weld, and I'm a) a bit old to teach myself anymore and b) if I tried to take a class, I'd likely be laughed out of it due to me being almost middle-aged, and thus should have learned welding long ago. :-/

guy153 03-17-21 11:32 AM


Originally Posted by MrInitialMan (Post 21971302)

The reason I was looking at these PVC plans is, well, I don't know how to weld, and I'm a) a bit old to teach myself anymore and b) if I tried to take a class, I'd likely be laughed out of it due to me being almost middle-aged, and thus should have learned welding long ago. :-/

Seriously it's not hard. "Too old to learn", and "almost middle-aged" does not compute. You don't need to go on a class. I learnt everything from YouTube and have made several bikes which haven't fallen apart. If I can do it anyone can as I am a huge klutz. For your project you don't need to learn TIG (which is harder and the equipment more expensive). Buy a cheap flux-core welder (a couple of hundred $) and a self-darkening hood (so you can weld with both hands-- much easier) and give it a go. If you post pictures here we can help out.

This is really going to be a whole lot easier than trying to make it out of PVC or wood or something!

MrInitialMan 03-20-21 06:58 PM

Sorry about my last post, everyone. I'd been up all night and was feeling more down than usual.

Doug Fattic 03-21-21 10:38 AM


Originally Posted by MrInitialMan (Post 21971302)
The reason I was looking at these PVC plans is, well, I don't know how to weld, and I'm a) a bit old to teach myself anymore and b) if I tried to take a class, I'd likely be laughed out of it due to me being almost middle-aged, and thus should have learned welding long ago. :-/

Lots of my framebuilding class students are retirees wanting to do something interesting with their lives before they die. All of them learn to braze just fine (although some of them wouldn't have been able to become masters even if they had started when they were young). Brazing is a bit easier to learn than TIG welding. One guy was given my class to him by his children as a retirement gift. He really didn't want to do it but his wife told him he had no choice because they had done a lot of thinking and studying of options for him. He ended up having a great time anyway despite his initial reluctance.

preyj 03-28-21 08:59 AM


Originally Posted by guy153 (Post 21958730)
It's much easier to learn to weld than it is to make a chassis or bike frame out of PVC pipe! Especially if you aren't too bothered about weight-- you can use thicker steel (like 1.6mm) and buzz it together with a flux-core welder, which only costs 100 notes or so. People are a bit snobbish about flux-core but with a little practice and a decent quality wire you can make an acceptable joint on material between about 1.6mm and 2mm thickness.

You can be up and running with a small welder in a day but it will take practice to to make a decent weld and understand what amps, etc. mean to the metal you working with. Another consideration is cutting pipe / tubing. A decent pipe cutter or the Milwaukee metal cutting circular saw are my choices.

Andrew R Stewart 03-28-21 10:05 AM


Originally Posted by preyj (Post 21988547)
You can be up and running with a small welder in a day but it will take practice to to make a decent weld and understand what amps, etc. mean to the metal you working with. Another consideration is cutting pipe / tubing. A decent pipe cutter or the Milwaukee metal cutting circular saw are my choices.


This welding learning thing reminds me of what a Chinese restaurant owner told me years ago. It only takes a few minute to learn how to eat with chop sticks. But a lifetime to become good at it. 35 years later I still agree.

As to cutting/mitering the tubes I would not suggest a pipe cutter (assuming the rolling wheel type) as most tubes most people will want to use will have thin enough walls so the tube will just flex away from the roller and the cutter can easily "walk" it's way down the tube's length as you run it around the tube. Hack saws, hole saws, grinders (i use a bench mounted one for roughing out some miters) and hand files are the low cost go tos for most of us when we started out. Andy

guy153 03-28-21 11:33 AM


Originally Posted by preyj (Post 21988547)
You can be up and running with a small welder in a day but it will take practice to to make a decent weld and understand what amps, etc. mean to the metal you working with. Another consideration is cutting pipe / tubing. A decent pipe cutter or the Milwaukee metal cutting circular saw are my choices.

Those are fine choices but an angle grinder with a cutoff wheel will do the job. As for making decent welds yes a bit of practice. The best thing for anyone starting out is break tests. If your welds are poor you will be able to break them. I'm talking here about flux-core welding 16-gauge mild steel for projects like the OP's proposed velomobile chassis. If you want to weld thin-wall bike tubes you need to learn TIG, thin-wall, thick-to-thin, and passing a break test is only the beginning of a good weld. I still think anyone can learn this but it takes a lot more practice.

Speaking of flux-core welds of velomobiles this guy's project is pretty interesting:


By his own account his welding is a bit of a "horror show" but it's good enough. He's very good at the machining and design aspects though.

squirtdad 05-14-21 03:53 PM

this may be on interest......

6 wheel bicycle, huge, ~20 mph electric. 5' x 10' - $1,600 (willow glen / cambrian)

https://sfbay.craigslist.org/sby/bik/d/san-jose-wheel-bicycle-huge-20-mph/7315728264.html

https://cimg8.ibsrv.net/gimg/bikefor...43010b776a.jpg

unterhausen 05-14-21 04:10 PM

It's for sale because they tried to ride it uphill.

I'm always curious why people undergo an elaborate project like that without looking at what anyone else has done. Afraid they might learn something, I guess

squirtdad 05-15-21 11:08 AM


Originally Posted by unterhausen (Post 22059789)
It's for sale because they tried to ride it uphill.

I'm always curious why people undergo an elaborate project like that without looking at what anyone else has done. Afraid they might learn something, I guess

it looks like it has a carbon bottle holder cage....weight counts :)


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