Quite fancy doing one of the frame building courses at some point in the near-ish future, either that or getting XCAD or similar to build something custom.

I’ve got my MEng so the theory and maths is there, but has anyone written a more practical/specific book on frame design?

http://www.bikecad.ca/
http://www.spanner.org.uk/

These may help.

I’m toying with the idea of a XCAD 140mm forked hard tail with yeti ARC style rear end.

how about getting a load of tube from ceeway and firing up the oxy-acetylene and just having a go?

how about getting a load of tube from ceeway and firing up the oxy-acetylene and just having a go?

The geeky side of my brain would tell me it’s going to fall appart because there was no maths involved in the design.

The practical side of my brain would tell me it’s going to fall appart because I haven’t a clue what I’m doing with the brazeing.

Just wondered if there was a book that covered everything from head angle, rake and trail to how long the butted bit of the tube should be.

I’m toying with the idea of a XCAD 140mm forked hard tail with yeti ARC style rear end.

29er, ritchey dropouts, EBB, no suspension correction (for a low top tube) and an integrated seat post, sized somewhere between a medium and a large singular swift.

That’s sewn the seed again!

draw a horizontal line – to represent the ground.

draw a 40mm circle – this is the BB – position it at a height of your choice above the ground.

represent each (26″) wheel with a 690mm circle.

position each ‘wheel’ so that it contacts the ground.

the rear wheel will be about 430mm horizontally from the BB.

the front wheel should be about 700mm horizontally from the BB.

(these numbers are of course subject to change).

look up ‘reach and stack’ – pay particular attention to the ‘reach’ measuremment – measure up a few bikes that you like for pointers, but somewhere around 430mm will get you going.

look up the dimensions for your forks.

there, that should keep you going for a while.

easy.

have fun reading this.. your geeky MEng side will love it:

Click click

Even mentions Fortran 😉

be bold, start from scratch and you might re-write the rule book.

maybe a 96er or something different try it and see

🙂

Im looking at bike design and thinking of new suspension designs and in particular new pivot systems.
I’d like to see a new bottom bracket design too

I’d like to see a new bottom bracket design

that’s the great thing about ‘standards’;

Don’t like the existing 27?

Invent another 😉

headtubes seem to be going through this phase at the moment.

The ‘classic’ book is “Designing and Building your own Frameset” by Richard Talbot. It’s out of print and quite hard to get hold of.

I did just that, very satisfying. You can get a bit obsessed.

The ‘classic’ book is “Designing and Building your own Frameset” by Richard Talbot. It’s out of print and quite hard to get hold of.

Not with a smart google its not:
http://bhovey.com/Masi/Scans/Talbot/index.htm

bikecad

ahwiles – Member
draw a horizontal line – to represent the ground…………..

easy

bikecad

Yes, but that’s neither designing, nor engineering is it, it’s just a pretty picture of something that looks like a bike. It doesn’t tell you whether the downtubes going to fold the first time you ride into a rock, whether you need a bridge to re-inforce the disk brake, what forces to condidder when calculating the stress/strain on a join and whether that justifies a gusset, and if so how big should it be, etc or whether your chosen combination of wheel size, head angle, fork rake and stem length will result in the the front wheel being stable, or flopping about from side to side.

I’ve neither a practical side or a geeky engineering side but I’ve just designed my own Ti ht which Enigma are building.

Basically I considered everything I felt was wrong with my previous frames, too short/long/tall/steep etc and went for my “ideal”. Checked the ideal against real frames of a similar intended useage to make sure I wasn’t way out and then added a load of things I wanted in terms of dropouts/stays and so on.

It’s essentially ended up being a Brodie Holeshot but with a tapered headtube and wishbone stays.

Obviously I’ve had to take Enigmas advice on things like butting profiles and their availability, stress risers and such but tbh I wasn’t far off with what I’d come up with on my own.

I’d do what IvanDobski says – design the lengths/angles/fittings/etc yourself based on ‘known quantity’ frames you have ridden and like and then get the framebuilder to recommend tubes that aren’t going to fold in half or weigh 3 times as much as they need to.

There’s also “The Paterek Manual for Bicycle Framebuilding”

It doesn’t tell you whether the downtubes going to fold the first time you ride into a rock, whether you need a bridge to re-inforce the disk brake, what forces to condidder when calculating the stress/strain on a join and whether that justifies a gusset, and if so how big should it be, etc or whether your chosen combination of wheel size, head angle, fork rake and stem length will result in the the front wheel being stable, or flopping about from side to side.

Please don’t read this the wrong way..

What did you learn when doing your MEng? Was it in Mech Eng?

Anything that you could apply to the design of a bicycle frame? FEA, joining techniques, materials properties, dynamics etc etc?

If you managed to get an MEng in Mech Eng (or any other discipline) should you not have quite a bit of the knowledge required to make a start on this? even just from a theoretical perspective?

Si

Don’t you just spec the basics then get the builder to make it all fit/work together?

I did that…my advice would be don’t do anything controversial/fashionable, I did….and it’s my only regret (slack seat angle on a hardtail) but it’s live-able with.

I guess my point is you ought to come up with something that’s not outwith what’s been done before (i.e. so it will work, in terms of angles etc) and the builder can spec the tubing so it doesn’t break – like Ivandobski up there.

I doubt there is much that works that not been manufactured before.

So the numbers actually make a difference to the fit and the ride, much of what one specs is about personal preference – for me that mostly was to look as much like a Fat Chance as possible 😉 round tubes, as few bends as possible, short head tube – the antithesis of that 29er above.

Why did you for a slack seat angle? (how slack?)

have a browse on pinkbike. there are a few threads on the forum there dedicated to people building their own frames.

Yes, but that’s neither designing, nor engineering is it, it’s just a pretty picture of something that looks like a bike. It doesn’t tell you whether the downtubes going to fold the first time you ride into a rock, whether you need a bridge to re-inforce the disk brake, what forces to condidder when calculating the stress/strain on a join and whether that justifies a gusset, and if so how big should it be, etc or whether your chosen combination of wheel size, head angle, fork rake and stem length will result in the the front wheel being stable, or flopping about from side to side.

and you can’t build your FEA models/start your calculations until you know how long tubes will be, or what diameter they are, or what angle they intersect at.

without spending loads of time/money on strain gauges and accelerometers you won’t have a clue about the forces involved. and without realistic forces your models/calculations may as well be guesses.

(you could squeeze a few phd’s out of the physics and forces acting on a mountain bike frame)

an easy way to calculate the ‘trail’ of your front wheel is to measure it from your CAD model, and then, if you’ve been clever and created it parametric-ally, you can change the head angle in a matter of seconds, and your measurement will change with it.

with a well set up drawing/CAD model, you can mess around with many things very easily and quickly.

etc.

you’ve got to start somewhere, and i still suggest that a good place to start is with a drawing.

if only so you can extract a .dxf file to send off to the laser-cutters for your custom batman logo dropouts…

Ivan – it was a trend at the time, or at least mba told me it was (that’s the only magazine I’d have ever trusted on this, and most topics) but it was only a trend on FS’s (if at all) and I was designing a 26″ hardtail…as I run it ss, a steeper seat angle would have helped I think, though it is comfortable to sit and spin on.

Things about it I like that aren’t conventional (but not so controversial they won’t work):

1. slack head angle – like 68 degrees or so – my other 26er is a Heckler (anyone that thinks a twitchy front end actually is faster, rather than just make you think it is, needs to think about that a bit more)

2. 130mm forks – it’s a light 20″ frame, 130mm head tube or so, meant for all day rides. I just down’t see how 80/100 forks make it any faster (they certainly aren’t going to be as much fun/skill compensatory.

3. long chainstays mean I can actually climb stuff* (anyone that thinks short ones are actually faster, rather than just make you think they are, needs to think about that a bit more)

* I run a Thudbuster with an extra bit of elastomer to push the seat forward to compensate for the slack seat angle.

4. As much clearance as I could get.

I guess in summary, and following you (Ivan) (tho I did it in 2005) take the bits you like from frames you’ve ridden that work, reject the rest!

I start with the main measurements head angle, seat angle , effective top tube length ,chainstay length , bb height seat tube length, head tube length wheel base, and wheel size ,
Look at what other companies have done and what works for you, then add your spin to it,
Draw it up the scariest bit is not sending a load of money off it,s the waiting for your new design , thinking off all the things you should have could have changed added etc,

FS bikes forget it, the first prototype is never right and can often take a few prototypes to get it sorted which can turn out to be very expensive it’s ok if someone else is paying the bills

MEng in chemical engineering, but my research dissertation was in trying to break CFRP hockey sticks of all things! So yes some of the theoretical knowlage is there, but knowing how to figure out the stress in a component, is different to knowing what force that component experiences, of which I havent a clue i.e. if I knew what the force applied to the end of a fork on a completely ballsed up landing at 20mph was I could make an attempt at designing the headtube/top tube/downtube/gusset, but I’ve no idea what that force is.

And I suspect a lot of it is probably rules of thumb and reynolds only make tubes that work in the real world. However stuff like this tends to be learnt from experience, which tends to get written down in books which are then bought by people wanting to do the same thing that took someone a lifetime of trial and error to figure out, but they want to do it in their 20’s, with less error.

In the same way you could learn to ride faster by:

Crashing a lot (build a frame and see if it works)
Reading the Brian Lopes book (what I’m looking to do)
Go see Jedi (go see Dave Yates for a course)
Get Steve Peat to dress up as me (get a framebuilder to build it)

3. long chainstays mean I can actually climb stuff* (anyone that thinks short ones are actually faster, rather than just make you think they are, needs to think about that a bit more)

Not sure I agree about this, but we all have our opinions of what makes a bike good, which is good if not we would be all riding the same clone bike, with the same kit on it , beside i seem to be one of two of us who think estay 29 ers are a good thing

And I suspect a lot of it is probably rules of thumb and reynolds only make tubes that work in the real world. However stuff like this tends to be learnt from experience, which tends to get written down in books which are then bought by people wanting to do the same thing that took someone a lifetime of trial and error to figure out, but they want to do it in their 20’s, with less error.

But experimenting and finding out for yourself is lots of fun!

ade ward – Member
3. long chainstays mean I can actually climb stuff* (anyone that thinks short ones are actually faster, rather than just make you think they are, needs to think about that a bit more)

Not sure I agree about this, but we all have our opinions of what makes a bike good, which is good if not we would be all riding the same clone bike, with the same kit on it , beside i seem to be one of two of us who think estay 29 ers are a good thing

You may prefer shorter chainstays, but really, are you telling me they are measurably faster?

I would say that if we are talking about a hardtail frame then don’t get too hung up on ‘the book’ as such. What ‘works’ is pretty well defined within quite a limited range. As Ade says, do your research, read lots, ride lots, discover what you like and what you don’t. Do lots of designs in BikeCAD (or AutoCAD if you want to get serious – but BikeCAD is very easy to use), above all think!

Bicycle Design by Mike Burrows is an interesting read. I read it before I started in the bike trade and it helped to work out my ideas on basic road geometry and fit for a couple of custom frames.

Cynic-al
Don’t like changing the subject on here especially as this thread is actualy interesting with some well thought out replies but as it is related to the subject ,I’ll explain how I see this,
You started by talking about climbing, then changed to which is faster, and often walking is the fastest way up the hills,

I think there are three reasons for failing to climb a hill
1 loping the bike front coming up uncontrolled
2 lack of traction , wheel spinning
3 lack of fitness and or will power ,

In my riding I’m afraid it is normally 2 or 3 which stops me on a climb , can’t remember the last time I was stopped by a number 1
Now if it was a number 1 which stopped me a longer wheelbase bike would help either by a longer chainstay of longer front centre

But number 2’s lack of traction , all things being equal the wheel with more weight on it has more traction so ultimate traction is when you have 100% of the weight on the rear wheel which means 0% on the front , so it’s a balancing act

But no matter how long the chainstay or wheelbase is you can’t get more than 100% rearward weight distribution so ultimate traction is the same so if you can control a short bike , it helps get over those nasty roots etc by keeping the front end light , and I like my 29 er short and nimble

As for number three lack of fitness and or will power sorry can’t help there, but sometimes it is faster to walk

Al – Cheers for the explanation, I had visions of some sort of semi-recumbent thing at first.

I’m waiting on the final drawings and then I’m at the point of no return.

As I said it’s basically a Holeshot so built around 140mm forks, long but loads of standover, dropper post routing etc and built to let me chuck it skill-lessly around the lakes without worrying.

I’m overly pleased by the idea of having a frame with no bottle bosses as well – simple things etc.

There used to be an excellent book on touring bike design by Tony Oliver.
Explained the basics very well.

I’ll see if I’ve still got it, you’re more than welcome to borrow it if so.

Don’t limit yourself to bicycle books there are some relevant stuff in some of the motorcycle design books , I can recommend the Tony foale book

I’m also keen to get into designing frames just from a personal interest angle (and having a mech eng background) but I think I’d like to get into the practicalities more trouble is every building course I’ve found is at least £1k+ and I’ve not really got a chance of getting that past the missus. Some Interesting thoughts on this thread though…

Seen these on Dirt?

http://dirt.mpora.com/?s=homemade&x=0&y=0

Just start by copying someone else’s design, both materials and dimensions. Learn about materials from making stuff that fails (hopefully gently). Don’t be put off by experts. Someone will have done it before, just google.
If you can’t weld or braze, do it in carbon, it’s not that hard.

I use rattlecad to design and build frames. The free version of bikecad is great for designing but leaves you a little short on information when it comes time to cut metal.

ade you mis quote me.

I’ve no idea what loping a front wheel means.

Long before you have 100% weight on the back wheel you will be wheelying up any climb…and then walking. If you don’t get that then you probably won’t get my reasoning.

Why do you think your short chainstays are better?

the ones I’ve read:
bicycle science-wilson.
paterek framebuilding manual.

still looking for archibald sharp’s bicycle tricycle book.

reading framebuilder’s blogs can be informative.