Hi All,

I work in a school in Preston, Lancashire and we have a GCSE student who wants to make a road bike frame.

You may have heard of him in fact:

World’s youngest Fusioneer

We have a CNC routing machine (1220 x 610mm or 4ft x 2ft) and he is drawing the parts on AutoCAD 2015.

I am looking for any advice/experience you lot may have. We have a lot of in-house experience in making furniture-type items and I personally have a good understanding of structures and mechanics, as well as bicycle anatomy, but with a project like this, I would welcome input from anyone who knows a bit about what they’re talking about.

As a starting point, we are looking at:

1) what current wooden bike manufacturers are using with respect to wood species for the various parts.

2) Using something like Planet X’s swapout dropouts for mounting the rear wheel and a disc brake.

3) Bonding in bought-in metal parts for headtube and bottom bracket.

Jamie has considered using birch plywood, but rejected the idea for aesthetic and aerodynamic reasons. We may still make a seatpost mount using the plywood.

Help that I know we need:

1) Advice on dropouts – any objections to swapout dropouts? Anyone got dimensions for them so we can introduce them to the model before purchasing them? I know Brant has moved on, but perhaps he can pull some strings for us? (emailing separately)

2) Where would you buy the metal parts we want to use?

3) Main question: What resins would people use for bonding wooden parts together? What resin for wood to metal? Same resin for wood to steel as for wood to aluminium?

Help we need that I don’t know about:

everything else….

Thank you in advance, because I know some of you will come through with some gems.

Sounds excellent – I wish my son’s school would support him in such projects. Ah well!

I would be clear about what you are trying to achieve.
What is the goal? Why wood? Why adding metal? What is acceptable and what is not in order to consider the project a success.

I would investigate carbon as a method of achieving some of the trickier parts.

There are quite a few makers of hand-built wooden bikes. A good place to start would be the ones who attended the NAHBS (North American Handbuilt Bicycle Show). There was also a UK equivalent (called Bespoked), but not sure if wooden bikes were present.

As you have already done – use the “World’s youngest Fusioneer” as a door opener to talk to these people directly. I’m sure the nature of handbuilt bike builders would be open and sharing.

Good luck!

Sorry, can’t help but please post the finished bike on here. Sounds like a fantastic project.

I wouldn’t dismiss birch ply as it works brilliantly on a flatbed and is very strong even at relatively thin thicknesses. At work we get ours through Arnold Lavers.

For wood to wood you could look at Titebond or Cascamite glues. I’d download their datasheets and look through them. Other than that you could try gorilla or even polyurethane glues. Polyurethanes can be used well to glue dissimilar (or similar) materials e.g. plastics to metal or wood to metal – just make sure you degrease the metal well. I wouldn’t just bond the metal parts into the frame, I’d perhaps use some grub screws or keyway(?) type things to prevent rotation.

You may get some of the parts you need from Ceeway. But I would just get some old frames and cut them to bits to start with.

Thanks for the responses so far. To answer a few questions:

AlexSimon:
I’m struggling to state the goal because the kids get a range of briefs to choose from and I am not sure which one he has chosen. Common to all projects though is simply to follow the design process from brief through market research, design, fabrication and evaluation.
We are using wood because we have the facilities here for woodworking. Metalworking kit went away some years ago. I think we need metal parts incorporated to support bearings and threaded parts (ie bottom bracket) and I was a bit wary of trying to make the dropouts out of wood as they would have to be quite thin to fit between the hub and the locknut.

I’m sure Jamie would love to use carbon fibre but I think the time it would take to run trial builds/build jigs and moulds/learn to lay up properly is probably too much. He is only supposed to spend 40 hrs making this thing and I think he will already have his hands full. Nice idea though.

I will defo check out the NAHBS information and look into Bespoked – thanks for those leads.

willyboy:

I personally would be in favour of birch ply. It would be much easier and I think give good, consistent strength. We use it extensively in school for many projects. It doesn’t lend itself to an aero frame though, and aesthetically a solid wood would be preferable. The final decision is Jamie’s and I think he has settled on solid wood.

I agree totally about not relying solely on the adhesive/resin/whatever bonding agent. We will be looking at some form of mechanical fixing method too. I will check out Ceeway – thanks for the tip.

As for the glue/whatever, I will have a look at data sheets – perhaps we will do some load testing of joints too. I was jumping straight on the resin track, but you’re right about not discounting normal woodglues – they will be included in any testing we do.

Again – thanks for the responses and Jamie and I will be keeping an eye on this forum. I may repost some of the specific questions under separate topics too, to try and broaden the audience.

Where is Oliver? He’s built his own carbon frames with similar metal parts for structural areas

there is a guy in ireland who makes and sells wooden frames linky
i dont know the guy, so have no idea if he could help in any way, or if you can glean any info from his website.

What about the bamboo bike brigade? They might have some useful points.

Bamboo bikes

http://renovobikes.com/pages/technology on bonding metal components

There are quite a few bamboo bikes around these days. If you are going to use wood, I’d guess that the tubular structure of bamboo will make beat solid wood on strength and weight.

Billy Minto made a bike out of bamboo and a cannibalised metal frame, using nylon tights and superglue for the joints:
http://skidmarksonthesemmits.blogspot.com.au/2011/12/bambi-update.html?m=1

Ash has traditionaly been used for building frames of old Morgan cars / Moggie traveller back ends. It has excellent shock absortion properties and is easily bent using steam. Very strong and reasonably light.

I don’t think simple wood will work – it isn’t stable enough, it moves a lot with changes in temperature and humidity, which is why guitars have truss rods. You need the grain going in multiple directions to stabilise it.

I think his best bet is a laminated monocoque made of layers of plywood, machining parts out in areas of low stress. If he does stepped cuts and then sands afterwards he’ll be able to get complex smooth shapes without having to do true 3D machining. Something like the Lotus bike should be possible. Where metal parts are joined I’d be looking to maximise joint area (sleeves or similar) and bonding with epoxy but also making the joint a tight mechanical fit.

This is an awesome project! I was tempted to make a balance bike for my daughter on our CNC machine at work but I didn’t have the time.

which is why guitars have truss rods.

that is not why guitars have truss rods.

i’d be looking at laminating with over lapping joints then machining out the bottom bracket and headtube

interesting project!

Here you go, have a read http://www.cycleexif.com/lyrebird-cycles-tonewood-project

http://www.woodelo.ie/bikes/leaf_speed

Wow, you guys are really into this – that’s fantastic!

Lots to go through. Let me address the issue of bamboo first:

I understand bamboo is a fantastic structural material for many reasons, not least it’s natural tubular structure. The project, however has to incorporate some form of Computer Aided Design/Computer Aided Manufacture to satisfy the GCSE requirements. So bamboo is out for that reason alone. I can/will suggest Jamie considers using bamboo for some elements of the design, but the bulk of it needs to be machined.

martymac, brassneck and murray – I will check out the linkys tomorrow; many thanks.

Chiefgrooveguru:

Many points. Firstly, thanks – epoxy resin was my first thought, too. I recently watched a youtube video on knife-making where the guy tried various brands/types of epoxy and they were certainly not all equal. I wonder if you have a preferred epoxy resin brand or type?

As for the stability of wood: we will have three layers probably (mimicking current designs of others), either side plus an inner “core layer. This will also allow machining on the insie to reduce weight. The plan is to assemble a rough-cut front triangle with the grain running longtitudinally with respect to the ‘frame tubes’, prior to machining. This should minimise expansion and contraction along the ‘tube’. The lateral expansion with moisture/humidity changes should be minimised by the fact that the width and depth of the tubes is going to be less than 2” (probably, maybe….currently). That’s the theory we are working on – what do you think?

Also we will be selecting woods for their stability as well as strength and stiffness. TBH, we will probably play it safe and copy what others are using – that is good enough material selection justification for GCSE level. Providing we show that other materials have been considered, of course.

The machine we are using is a Boxford CNC router and has the ability to take a 3D model and create a cutter path that ‘steps’ in the way you mention; it will repeat the job using different stepping methods (ie with cutter travelling parallel to x-axis, then parallel to y-axis, then stepping by following contours defined by the 3D shape and then others still) to get us very close to the final shape for minimal sanding.

And I’m afraid I don’t kow what a guitar truss rod is but I promise to do my homework on it tomorrow!

Thanks again to all – your input is very much appreciated on this. I’m sure you understand that this is a very exciting and challenging (and slightly worrying) project for us!

Thank you davidtaylforth and bullandbladder – I will read with gusto on the morrow.

Suggest you also research wooden boats – in particular mast making which will incorporate may of the things you are looking for. Masts have to be light and strong and get enormous shock loads.

The book by Gudgeon Brothers used to be the bible for boat building with epoxy, and it contains loads of useful info on bonding metal to wood.

(I’m afraid my knowledge isn’t current, it’s been quite a few years since I last built a boat, and I’m not familiar with UK woods)

Hi Mickolas

I work quite nearby (and went to school at All Hallows many years ago). I make steel frames as a hobby, and did a steel and birch ply folding bike for my degree project. Also made a wooden unicycle….. Feel free to drop me an email (address in profile).

Steel and aluminium frame parts (bb shells etc) are easily bought from Ceeway, or salvaged from scrap frames. If you just want a length of head or seat tube then I can probably find something.

If he designs dropouts in Autocad then very easy to get water cut from a dxf file in aluminium etc – lots of local companies.

Plenty of wooden frame methods at the Bespoked show – look back on their previous year’s web pages for exhibitor details.

Also google:-

Sandwich Bike
Jano by Roland Kaufman
Carbon Wood Bike by Gary Galego
Axalco
Supernova Design
Sman Cruisers
Sanomagic
Art & Industry

Adhesives – I just used Cascamite for wood and epoxy for wood-metal.

“The New Science of Strong Materials” by JE Gordon had a good section on caesin wood glue and plywood.

If he is a capable and engaged kid then happy to help.

Might be worth contacting the owner of Woodelo for guidance?

that is not why guitars have truss rods.

So why do guitars have truss rods?

To counter act the bowing effect from the tension of the strings.

A neck thin enough to be easily played is too flexible* to remain straight and it needs to be straight to allow fretting of the string the trussrod** forces a backwards bow to counteract the pull of the off centre load.

*steel strings. Nylons have no truss rod.

** other options can be used. Such as cutting slightly narrow fret slots to create the bow when the frets are forced in. And the use of some materials like carbon wraping and inserts can make the neck rigid enough but these options are pretty tricky to get right and if you want to fit heavier strings you may be out of luck.

And while wood can be unstable its not generally in the direction of the grain and a good coating of varnish will generally reduce the effect anyway.

Mast building is a good idea particularly birdmouth construction.