joseph h

hello,

When I was a kid I was very much into moutain biking, I eventually grew out of it for a number of reasons including being very prohibited by the cost. I've recently sorta become itrested again, and looked around at bikes and frames. I'm a fairly accomplished welder, and my firtst thoughts on seeing some of the prices on frames were "I could easily make that for half the cost".

So has anyone here built their own frame? Any suggestions? Jigs? Advice?

monkey69

forgett it ,it will cost you twice as much ,if even possible.a frame ain't a bunch of pipes welded together !!

joseph h

I don't mean to sound rude here, but well, isn't a frame just a bunch of pipes welded together?

I own or have access to pretty much all the equipment I think I could possibly need. As well as having experience in building motorcycle and ATV frames (in a production setting, I'd prefer to TIG a bike frame).

My main question is what type of steel to use, other than that I'd just copy the measurements from some existing frame, set up a jig and go.

khuon

Check out this guy's two homemade MTBs. One is made of CF and the other is bamboo with CF lugs.




The guy who built this bike also built his own seatpost (both CF and bamboo) and saddle (CF).



He also made his own CF headset.



And check out his front CF hubs.



He fabricates his CF parts from prepreg. There's of course some aluminum inserts for head tube, seat tube and BB shell. He claims the thing weighs 23.6 lbs. (frame weighs 4.1 lbs.) which is pretty good for a hardtail MTB... wood construction aside. This is his second bike that he's built. The first one was a full carbon fiber frame.



They both look pretty good for an independent homebuilt... hell, they look pretty good regardless.

He says he was inspired by Craig Calfee who also once made a bamboo road bike and mountain bike.

erhan

If I were to build my own frame, I wouldn't use steel. I would go for 6000 series aluminum, or titanium. I think steel would be too heavy unless you don't have weight concerns. IMHO a frame weight shouldn't be over 4-5 lbs for hardtails.

I have no idea, or experience about welding, but I think the challenge here will be building the head tube, BB tube, angling and spacing the seat stays precisely.

Keep us informed if you start the project

monkey69

well if you keep it very simple ,without 3d dropouts etc. yes it just some tubes .but you still need to know how to fabricate metal.i am not a welding expert in any means ,but as far as i know,aluminum welding is extrmely difficult .all in all it would be more like a month project ,rather than something easy and cheap to do .
also hardtail frames really aren't that expensive .
btw. i wonder how that guy made the carbon parts .i thought u need a high pressure high heat press for that .

kandnhome

Here's the page of that guy whose bamboo bike is posted above; it has a jig that looks like it would work (or at least give a good idea of where to start) for a metal framed bike.

https://www.bme.szm.sk/carbonframe1.htm

If you do build it, remember to come back here and post some pictures of the progress and final product!

Good luck

khuon

Yes and no. There are many ways to form and cure carbon fibre structures. Damon Rinard has one of the definitive guides on how he built his bikes in his garage.

jhota

i know guys that have "homebuilt" car and motorcycle chassis at home (in a very
well equipped home shop), why not a bike?

as for tubing, you'd need to buy a tubeset (or sets) for bicycle use, not just any old pipes lying around.

and a true jig would be crucial.

but it's not impossible, and would probably be rewarding. it'd be cool to show up for a ride and have someone ask, "what kind of bike is that?" and be able to say "mine."

as for geometry, i don't have any modern (post mid-70's) books on bike-building theory and frame geometry, but that doesn't mean they don't exist.

phantomcow2

I dont know, i wouldnt attempt it. If your a really good welder i would say go ahead. You need to make su re many things are very accurate, the headtube would probably require a lathe. You have to make sure your spacing is right, the threading for BB, too much to go wrong

khuon

There are a couple of BikeForums members who are also frame builders. Thylacine is one. Also, dexmax has built his own roadbike frame.

majorpayne

I believe that I am going to attempt this sometime in the future, the hardest part will be finding the right materials and setting up the jig so everything is setup right. I'll probably use aluminum if i can find the right size tubing around here, otherwise I'll use chromoly tubing and turn it down in a lathe so its thinner walled and will weigh lighter in the end. This is a technique that nascar teams use for their tube frames, they turn every piece of chromoly down approx .005-.008 and it can save them up to 15 lbs on the entire car. If i cant find the right sized alum, im gonna turn down the chromoly down as thin as i can get it. But ill probably do some stress testing at school to determine how thin i can go. Because the Chromoly is stronger than aluminum, i can hopefully get it about half the thickness if not more, and with some strategically placed gussets, get them even thinner, as the points where tubes meet is always the weakest spot. I'm not completely sure what style frame i want to do yet, and i have too much on me right now to start it, but ill start figuring things out and let you all know what i come up with. I have a fairly extensive welding and machining background as well as general fabrication, and have built motorcycle frames and all kinds of rollcages and whatnot...so to answer some questions 1) yes alum can be tricky to learn to weld at first (TIG), but its not impossible and once you get the hang of it its pretty simple and its like second nature to me now. 2) The best steel to make a frame out of would have to be Chromoly IMHO, first of all its the strongest readily available steel tubing out there, and second for its corrosion resistant qualities compared to a regular mid to high carbon steel. (3 Titanium isnt a bad idea, but goodluck finding someone who knows, or for that matter has the artificial atmosphere equiptment you have to have in order to weld it, plus its gonna be expensive to buy.

kritter

Why all the nay sayers?

It's easy to do if you know what you are doing.
A bike is made from tubing not pipe...big difference in a fabricators mind.

Go for it. Find a bike you really love the feel of and use that geometry. Welding aluminum isnt hard if you know how to TIG weld....heck wire feed mig welders lay a pretty good aluminum bead these days but I would tig it.

The bottom bracket, head tube, and rear drop outs are easy money to machine up....a buddy did a cruiser in college out of sheetmetal and tubing and he was able to find the bottom bracket already machined from a local shop. The bike had a 100" wheel base and was a mofo to ride but people loved it and he ended up being hard up for money and selling it to somebody at the beach for a lot of money.

Go for it...there is no reason any competent fabricator can't build a bike.

If I was building a custom bike I would use 4130 chromoly tubing or something exotic like Ti, but thats just me.

kritter

"2) The best steel to make a frame out of would have to be Chromoly IMHO, first of all its the strongest readily available steel tubing out there, and second for its corrosion resistant qualities compared to a regular mid to high carbon steel"

Anybody arguing the fact of chromo vs mild for corrosion resistance properties...turn and walk away. All forms of steel suck when it comes to corrision except for stainless.

I think it would be bad ass if you made the thing out of 4130, had it scoth brited down to remove all mill scale and then have it electorless nickel plated about .001" thick in a mid to hi phosphorus bath...you would be very impressed with the results....you would get corrosion resistance up to about 300 hours of salt spray which is about half of powder coat but powder coat isnt badass like nickel plating.

Bigwheel

That's what I was wondering...some of the advice was painful to read.

You can buy tubesets, BB shells, drop-outs, braze-ons, etc...

You don't need a lot of expensive equipment, tools and jigs.

If you already have a good handle on working with metal, you're way ahead.

Have a look...

https://frameforum.net/
https://www.thebikestand.com/framebuilding.html
https://www.littlefishbicycles.com/frame/
https://www.phred.org/~josh/build/build.html https://www.angelfire.com/ma4/racine/framebuilding.html

majorpayne

i wasnt saying it was going to be a lot better as far as the corrosion resistance, but sit a piece of each in your basement and see which one rusts first, anyways, you wouldnt want to make a frame out of ss. And thats not even a big deal, its really a moot point, considering its gonna be coated/painted/etc.

Hopper

What you will want to do is, Workout EVERY little dimension you can think of that you will use on your bike, get a large piece of flat wood, draw your design on it. This is now your jig. Make or buy things like dropouts, heat tube and bottom bracket. Secure these onto the board. Get the tubing you need, cut it PERFECTLY there is almost no room for error here, and remember you just can't cut th tube flat, it needs to wrap a little bit around the tube it is joining onto. Place all tubes in your jig and make sure everything is secure. Start to weld up.....

I have never built a frame, I reckon it would be cool but can nt see it happening in the future. However if I were to build a frame I would be following something similar to this. Basically I would make do design, make a jig and place the important things like dropouts, BB and HT on first. Also I would probably use Cromoly 4130 steel, this would mainly be because it is easier to weld Cromoly than Aluminium.