Glued together CNC’d 7075 alu frame….

What would be a better shape then ?

What would be a better shape then ?

Google ‘generative design bike frame’.

Do you want me to make an innovative CNCd bike frame?  Fine, I’ll make an innovative CNCd bike frame.

Edit: for example:

I wanted to give generative design a try to I made this balance bike for my son with an @formlabs Form 3L. The frame weighs less than half of the original steel one.

(seat and fork from an off the shelf bike) pic.twitter.com/ngKBg9SxNT

— Maxim Lobovsky (@MaxLobovsky) January 12, 2022

that has 2 triangles, wonky ones, but triangles

The question is, why did they go with the double triangle.  Is it because this is simply the best possible design?

Triangles are extremely strong. Bridges, houses, etc. generally use triangles in the parts that are under stress.

that has 2 triangles, wonky ones, but triangles

You are correct.

In addition to those two triangles it has several other triangles and other shapes.

Triangles are extremely strong. Bridges, houses, etc. generally use triangles in the parts that are under stress.

Yes, that’s why when the only option for building bike frames was to braze steel tubes together over an open hearth, the double triangle design was settled on.

We no longer braze steel tubes together over open hearths.

In addition to those two triangles it has several other triangles and other shapes.

Yes, but none are what i’d call particularly attractive, but maybe that just proves your point of bikers being narrow minded 😀

Yes, but none are what i’d call particularly attractive, but maybe that just proves your point of bikers being narrow minded 😀

Yup, mountain bikers like bike-shaped bikes 🙂

Do you want me to make an innovative CNCd bike frame?  Fine, I’ll make an innovative CNCd bike frame.

The only innovation there is that it’s not as strong as it would have been if it had just been made from two triangles.

This seems to be a expensive solution to a question that nobody is asking.

The question may be asked by the people behind the brand though – how does a small company make frames in the USA without the resources for trad welded production ie a potentially smaller, leaner company? How do they make frames without heavy investment in tooling for forged parts and instead keep flexibility for geometry and part fits? How do they offer something that goes up against carbon fibre but is recyclable and less resource-needy for production?

From a rider’s pov none of that matters but if (IF / or when) cost and performance are competitive then changing the manufacturing process is one way to make a business work. Fair dues to anyone who actually makes their own stuff in-house or domestically, whatever the methods.

The only innovation there is that it’s not as strong as it would have been if it had just been made from two triangles.

Just to clarify, that’s not me.  Just an example.

And no, you’re wrong. It’s almost certainly stronger and lighter.  That’s the beauty of generative design.

Once you move away from the idea that you are making your bike frame out of tubes the possibilities are endless.  I believe that the Psalm is made in two pieces but there is no reason not to have multiple layers that can be glued together (a sort of poor man’s 3d printing) with epoxy mixed with high density filler used to create fillets to prevent stress risers.

We ended up with the double triangle design because that was the most cost effective design solution over 100 years ago.  Once you move away from tubes to CNCing solid materials the only possible explanation that you ended up with a double triangle design is because you’re going to be trying to sell your frame to mountain bikers.

Anyway, I’m going to fire up FreeCAD and see what I come up with.

Generative design suggests that design as an art form is something AI can’t replace yet. Those generated shapes may be stiffer/lighter but I don’t really want a frame that looks like something washed up smelling bad on a beach.

It’s at the stage of letting the AI do the work and showing the results unfiltered, and they’re interesting for sure. Generative design as a early round of design that’s then brought into proportion and balance by someone with an eye for it may be the real step forward in industrial design.

Edit to add,

Once you move away from tubes to CNCing solid materials the only possible explanation that you ended up with a double triangle design is because you’re going to be trying to sell your frame to mountain bikers.

Perhaps the (sensible) brief was to make a high-performance, commercially viable and marketable MTB that used CNC for business structure reasons, rather than reinvent the visuals and construction of a frame completely. tbh $5000 doesn’t look as viable as it could be to me but maybe.. Or maybe it’ll come down in price like the Hope frame did.

Those generated shapes may be stiffer/lighter but I don’t really want a frame that looks like something washed up smelling bad on a beach

Yup, mountain bikers like bike-shaped bikes 🙂

No shit eh : ) People like products that say the right things to and about them. Not just bikes.

No shit eh : ) People like products that say the right things to and about them.

Mountain bike designer:  We’ve thrown off the shackles of design limitations and created a mountain bike that outperforms everything else in the field by every measurable metric.  Not only that but it costs less.

Mountain bike reviewer:  It’s all true.  It’s better in every way.

Mountain bikers: It looks weird.  I think I’ll just buy a Trek Session.

Mountain bike designer:  Let’s just make a Trek Session.

Ministry? Psalm? It will either succeed or suck eggs

(Obscure musical reference, just  couldn’t resist)

No, it’s because they know that mountain bikers won’t buy a bike that doesn’t look like a bike.

At least roadies have the excuse that the UCI is literally trying to retard bike design and keep it strictly the way it was at the end of the steam age .  What excuse to mountain bikers have?

Approach this from the other end, what does a current twin triangle bike fail to do, or can be improved upon?

If you assume that geometry is roughly how we want it, and the basic concept of the upright bike remains

And that we are keeping with a telescopic fork and normal wheels – all made by 3rd parties

Is there a better way to do suspension rather than a rear end that moves in relation to the fixed front “triangle”

Is there a better way to acheive the results of a dropper post rather than by using a 3rd part telescoping tube pointed roughly down towards the BB.

You have a bottom bracket, a seat tube, a head tube, and rear dropouts.  How you connect these is up to you.  If you are going to use tubes then double triangle makes most sense.

If you are using a CNC machine then there are suddenly a lot more options.  When you are designing a bike for out and out performance and you aren’t using tubes the design you come up with is unlikely to be a double triangle.  Just look at the Lotus bike Boardman used.

Didn’t look like a bike-shaped bike so it was quickly banned.  Mountain bikers self-ban non-bike-shaped bikes which is even more sad.

What Olly said – rendered frame pics look ace. Full bike build pic, awful. Like a lot of new bike related stuff though thats produced like this on a small scale, I just have to ask “why?”. Customisation etc is easy using welded tubes so I don’t get that argument…

Design homogenisation in mature markets is a real thing. New cars and brand logos as prime examples.

If you are using a CNC machine then there are suddenly a lot more options.  When you are designing a bike for out and out performance and you aren’t using tubes the design you come up with is unlikely to be a double triangle.

Maybe the Slingshot, Trimble and Red Alp were right after all? : )

I’m with you on the bike industry often taking small steps and mainstream products getting dull but there’s no shortage of smart engineers trying to do things differently for concept bikes or portfolio pieces. Yet bikes generally end up connecting points with tubular or beam-sections because strength to weight and stiffness to weight need to be optimised. No doubt an AI-designed MTB FS frame would look different and improve the ratios but it’ll still have 4 familiar fixed, necessary points joined up.

CNC is not something I know a lot about but I’m not sure if it really gives as much freedom of form as you suggest because it’s still Aluminium, a different (assumed stronger) alloy as you don’t need to weld it, but still with same stiffness to weight and the concerns about denting if you go too thin wall etc. So if you don’t want a heavy FS frame and are using CNC it’s going to err towards a main triangle or large beam and a rear triangle or swingarm, triangles or beams as a starting point. I suppose you could CNC an AI type organic structure to a very limited extent but why would you, you’d print up a frame like that rather than sculpt it out.

CNC is not something I know a lot about but I’m not sure if it really gives as much freedom of form as you suggest because it’s still Aluminium, a different (assumed stronger) alloy as you don’t need to weld it, but still with same stiffness to weight and the concerns about denting if you go too thin wall etc.

Without going too specific, the downsides to CNC are the inability to do internal holes, and the implications in cost and time when your finished shape is more volume removed from the uncut billet.

Therefore if you want to any sort of “tube” ie any sort of closed section which are much better torsionally to form any of your structural members it needs to be in two halves and glued. Likewise for the headtube, there is no way to make that hole in one go.

And making a flat(ish) element – each frame half is about an inch thick i’d guess – is the way to go.

^ That’s it, that’s the sort of problem I was thinking of when saying you can’t make an AI-type shape via CNC – there’s some areas you just can’t get at in CNC and the removal of material Vs addition of it in material use, time, general efficiency.

It’s possible if you manage to get your head away from tube to tube construction.

Also, you have to get away from the idea that there is only one way to use a CNC machine and that the only way to do it is to cut two pieces and join them in the middle.  All you have to do is create flat planes.  The orientation doesn’t matter providing you’ve got face to face contact and neither does the number of pieces (within limits, you obviously don’t want to be trying to glue 300 individual pieces together).

Since the tubes are difficult to CNC, let’s start with the headtube, BB, and seat tube and figure out how to connect them together using a series of CNCd parts layered together with fillets made from epoxy and high density filler (poor man’s 3d printing).

Anyway, that’s how I’d go about it.  Not sure if my description is making sense the way I’m describing it.

You may just have to wait until I’ve done my CNCd frame 🙂

Have to say having now followed this guy/brand in the op on Instagram for a few days, I quite like the styling and design.