[Closed] Designing a bike frame

170mm full susser, 63/64 degree head angle, longish reach that is between mainstream long and "out there" long like the Nicolais, low BB, adjustable chainstays, a leverage ratio that is linear to aggressively progressive in the last 20 percent of travel and a coil shock mounted as low in the frame as possible - like the Ancillotis or an enduro version of the Commencal Supreme.

😛

Cheers.

Theres a dude on here who build his own carbon full susser. Look out the thread. Its amaazing!

Not sure designing a rigid would be that challenging..although building it would be a whole differnt story..

Should add..not an engineer!

I've seen that carbon full susser but can't find it again (joy)

Do you have a link?

Tom that's great information! Perhaps you can place an order :p

Cant find it either im afraid! Id like to see a really slack 120 travel bike. Might be hopeless, but I love slack bikes but anything with a 66 degree ha or less is far to burly for trails I ride.

That's a bugger.

I'm tempted by a slack hard tail, perhaps I need to do a poll?

I'd do a proper children's bike - something designed purely for smaller people. Weight and Geometry very important. Cable management very important and a BB/Headtube compatible with standards for headsets and BB's.

This is what I build for my lad from a Stock Halfords 24" Carrera Blast

http://singletrackmag.com/forum/topic/dads-building-the-nice-24-wheeled-mtb-for-your-kids-crank-info-and-build

I frame wise, headtube needs to be slacker and cable mounts need to be tight against toptube underside running down seat stays.

We can start a business to hammer Islabikes overpriced push irons.

johnski15

I've not considered that but I've always be intrigued by children's bikes, why are they so crap!

That bike you built your lad looks great.

My only concern would be that I dont have any experience on children bike geometry, nor do I have a child (unfortunately) to design one around.

If i do it, I will post all of the designs and FEA results online for people to use as they please.

where would i find specifications for currently available components if possible at all.

Hi James,

Thanks for the note that would be a great help. I've dropped you a PM.

Owen

A nice steel or ti hardtail with the geometry similar to modern enduro bikes i.e. Lots of fun on the rough stuff but would climb like a dream, light and strong enough for s big guy. I know there's s few around - Stanton, Coctic, evo456 etc, but they all seem to have compromises built in, I want a full on rowdy hardtail for 160 forks, big tyres and a 65 degree head angle with a decent reach and shortish chain stays!

johnski15 - Member
I'd do a proper children's bike - something designed purely for smaller people. Weight and Geometry very important. Cable management very important and a BB/Headtube compatible with standards for headsets and BB's.

This is what I build for my lad from a Stock Halfords 24" Carrera Blast

http://singletrackmag.com/forum/topic/dads-building-the-nice-24-wheeled-mtb-for-your-kids-crank-info-and-build

I frame wise, headtube needs to be slacker and cable mounts need to be tight against toptube underside running down seat stays.

We can start a business to hammer Islabikes overpriced push irons.

[url= https://www.propain-bikes.com/ ]Propain[/url] do both a HT and full sus kids bikes with modern geometry and claimed weight of 10.5kg for the full sus;

[img] [/img]

I've seen that carbon full susser but can't find it again (joy)

If you go full suss be prepared to spend alot of time checking the kinematics.
My breif for my biuld was long seat to head tube 150mm travel 29er that peadeled (very little chain growth) well with 21.5 equivalent seat tube.

Pick a few frames that work and study there travel path, geometry and form a conclusion.
There is some info on suspension design (not much though) read it.
Hours between bike checker and a solid works dynamic block sketch will follow try to get the axel path right. I focused on chain growth and travel.

You can FEA some linkages i work on 1.5 x my weight on one linkage. But thaf was only to determin thickness.

I found the rear triangle is the most difficult to get right as you are squeezing linkages, chainrings and largeish tyres into the same space.

Hmm turned into a long post, sorry.

I want a full on rowdy hardtail for 160 forks, big tyres and a 65 degree head angle with a decent reach and shortish chain stays!

This this this! I'd buy one.

Don't mind ally/steel/ti just proper geo and not a minger 🙂

For my A levels back in 97/98 I designed and built a full suspension frame. It had a whopping 1" of elastomer controlled travel, 20 wheels, single sided front and rear with centre hub steering. Mike Burrows said it was overkill but I thought it was the perfect rural shopping bike...

Because of my slightly biased past I say up your game and do something a bit more interesting especially if you're only going to FEA it and only maybe make one.

For my A levels back in 97/98 I designed and built a full suspension frame. It had a whopping 1" of elastomer controlled travel, 20 wheels, single sided front and rear with centre hub steering. Mike Burrows said it was overkill but I thought it was the perfect rural shopping bike...

Keith Scott from Banshee did his thesis on the design of their Legend DH bike:

http://www.scribd.com/doc/30562631/Design-a-New-Style-Suspension-Linkage-and-Frame-for-a-Full-Suspension-Mountain-Bike-for-Banshee-Bikes

When I did my carbon full suspension frame a few years ago I managed to find enough details on line for things like the brake mounts and rear mech mounting plates, so there should be even more available now.
As for FEA, much easier if you use a metal for the frame, unless your software can cope with carbon, and the orientation of each carbon layer.

kevj - Member Propain do both a HT and full sus kids bikes with modern geometry and claimed weight of 10.5kg for the full sus;

Mate I love those - but the cost is immense (to me anyway).

I built mine for £450-90, you might see more kids out it they were in that price range

What's the actual module OP?

Is it FEA based or a full design (and build) project they're after?

You seem pretty focused on the FEA side of things.

That could be my thread and to be fair i have to find it via google.

Also:
http://singletrackmag.com/forum/topic/carbon-full-suspension-frame-build-updates

No engineer so daft question but..

Surely the design (not build) of a steel hardtail is far too basic for an engineering project?

Sure youd need to specify materials and geo, but I reckon most of us could have a good bash at that based on our personal bike preferances.

given the nature of the project and fact he may not actually have to builld it, wouldnt a full susser and the challenge off suspension design be a far more challenging proposition?

Caveat is im no engineer, so may be talking pish. Intereted to know however!

cheers_drive - I also did a bike design as part of my A levels and went to see Mike Burrows for advice. My questions and subsequent designs were so superficial, the questions I'd ask now would be so different.
My parents found the designs in the loft a few weeks back, I'd even designed what looks like a gravel bike, ahead of my time me.

I never got to meet him, just had a letter that took about 3 months as the only way I knew to contact him (back when emails weren't really a thing) was to go through Giant UK.

I'm also curious about the module as this

If all goes well i would consider having one made but would be more likely to upload the models as "open soure" for you guys to play about with, modify or build.

Surely the design (not build) of a steel hardtail is far too basic for an engineering project?

I partly agree, but engineering is only partly to do with making something. The whole process starts with the requirement (which may come from marketing or sales). In this case the OP could write a fairly challenging requirement, very light, or very stiff or both, or to meet a cost target, and show how he/she has achieved it. The actual 'engineering' may be a small part of the project.

conduct and indepth review, effectively use finite element analysis and justify material types and manufacturing techniques.

This sounds like part of a brief, dare I say it they're not too bothered by what you choose to design or the details (geometry and application), they're looking for you to define some design selection criteria that can be substantiated through CAD and FEA...

If it has to be a bicycle frame, I would go with the HT or fixie and set some obvious, addressable criteria such as:

-Weight
-Strength
-Cost
-Flexibility/give (as in elastic range).
-Typical failure modes
-Manufacturability

Define a set of load cases that help measures some of the above (cost and Manufacturability are separate research).

Choose your preferred geometry, freeze it and then model it three times in steel, aluminium and Carbon (add Ti if you really want more work) account for available tube sizes, variations in section and model weldments.

[u]If you have the time/resources[/u] I would suggest finding a donor "control" frame or two, steel or aluminium which you are able to model reasonably accurately (including materials) and run through FEA as much as you can.. And then physically test, applying some of the load cases you modelled looking for the testing to reflect the deformations and failures from your FEA, this would demonstrate that you had tried to refine your understanding of stresses and the load cases applied to give confidence in your analysis.

Write your report as purely justified by the analysis, avoid personal bias...

Forget making a frame... Lecturers prefer marking reports to welding...

Hi All,

Firstly thank you for great feedback and discussion I'll need some time to review all of this info and make a plan.

The unit is ENG208 ENGINEERING DESIGN.

COOKEAA comments are well reasoned. This assignment (40% of module) is specifically around the design process, meeting customer requirements, and validation requirements.

Comments from the assignment:

You must consider in your design following sections;

Product specifications,
Identifying customer needs, Opportunity for design, Market Gap, etc that helping you for your concept generation
Concept generation (hand sketching) and selection,
Design for manufacturing,
Material selection,
Concept testing (FEA) for evaluation of performance and safety*,
Product development economics
Market Plan
* To prove your concept, you are to carry out, Finite Element Analysis (FEA) on your final 3D model. You are to consider what ways your chosen product could fail due to faulty manufacture or in use (Stress Analysis).

So whilst I have pretty much free reign on product, the validation and design detail needs to suitably support this. Perhaps this is where a hardtail or fixie would be most suitable. But I would like to do something which I may either make or release free for my own enjoyment.

I certainly agree that going metal Ti, Aluminum or Steel will be the most suitable.

The criteria I am working too is:

Grade Categorizations of criterion and associated grade letters
A An assured examination and use of FEA, covering all the content of the report set out above, together with a minimum of tutorial guidance sought, innovative design solution, understanding the market, procedure of manufacturing, use of material.

In terms of "understanding the market" it is possible that a well valued high performance mountain bike for children would be considered market gap. I believe one could suggest confidently that the adult cycle market for the product I specified in the original post are saturated, so I would need to clarify my reasoning and justification of design their (competitive edge) to make sure I am on the marks, so-to-speak.

If this goes well, it may also work well for me to take forward (in concept) in to my final year thesis (double unit project). Which would include, manufacture and prototyping. (FUN).

Thanks all, look forward to further discussion.

thepodge,

Just to clarify, I have to complete the design work as part of the unit, but it may be advantageous once complete (if any good) to make it available online for other people.

There are a million and one models of bikes and bike bits already out there. Just put bike into Grabcad and you get thousands of results. I'd focus on what you are supposed to be doing not on what you might do after you're finished.

I often wander round the first year projects at my old uni and the quality is phenomenal compared to what we used to put out but there are never any bikes, our lecture always used to insist that we chose a subject that we weren't familiar with so we had no preconceived ideas.

Interesting project! Cookeaa put it much more eloquently than I could so, "wot he sed".

It sounds very similar to what I had the chance to do as a final year project at uni. Although, I was working with 3 others and we did have to produce a working prototype. I've since built several other 'homemade' frames with the latest being a full suss design.

With that in mind, I'd echo the "go with a hardtail" design. It will be simpler to model and create test cases that you can then clearly demonstrate and elaborate on. Which is arguably what you'll be marked against.

Designing an extra mechanism in there is a nice to have but it's a whole heap extra work to design and analyse it well but it's only repeating the same techniques several times from a educational assessment point of view so you'll be doing extra for no reason really.

Fun though, enjoy it!

Interesting thread..look forward to following it. Have you thought about a bike for disabled users?. An off road trike or a hand bike. I'm coming at it from the market gap perspective but it might give you a bit more of a free reign design wise too. Just a thought.

The podge

Just to clarify I'm 2nd year. And im 24 and work in a professional engineering role already. I need to be able to have well designed and justified product in order to be able conduct feasible and reliable fea studies and stress analysis, so design is a critical element. Along with the rest of the project, dare I say it whilast the design elements are only a section without a feasible design I believe it would be a struggle to take full advantage of the other available marks.

Which ever is go with will be well reasoned and justified, also I have deliberately asked the questions to not just design for my own preconceived ideas.

Paul@rtw

I really am looking forward to getting started that's for sure.

I think you're on the right lines that a full suspension will be overly excessive work without necessarily any sizeable gain in mark.

I am very interested in doing a hard tail, 24" "proper" children's mountain bike at an affordable cost level. The design work has plenty of elements, I could justify a gap in the market and should be able to build a substantial project around this.

Thanks all

The podge

Just to clarify I'm 2nd year. And im 24 and work in a professional engineering role already. I need to be able to have well designed and justified product in order to be able conduct feasible and reliable fea studies and stress analysis, so design is a critical element. Along with the rest of the project, dare I say it whilast the design elements are only a section without a feasible design I believe it would be a struggle to take full advantage of the other available marks.

Which ever is go with will be well reasoned and justified, also I have deliberately asked the questions to not just design for my own preconceived ideas.

Paul@rtw

I really am looking forward to getting started that's for sure.

I think you're on the right lines that a full suspension will be overly excessive work without necessarily any sizeable gain in mark.

I am very interested in doing a hard tail, 24" "proper" children's mountain bike at an affordable cost level. The design work has plenty of elements, I could justify a gap in the market and should be able to build a substantial project around this.

Thanks all

The podge

Just to clarify I'm 2nd year. And im 24 and work in a professional engineering role already. I need to be able to have well designed and justified product in order to be able conduct feasible and reliable fea studies and stress analysis, so design is a critical element. Along with the rest of the project, dare I say it whilast the design elements are only a section without a feasible design I believe it would be a struggle to take full advantage of the other available marks.

Which ever is go with will be well reasoned and justified, also I have deliberately asked the questions to not just design for my own preconceived ideas.

Paul@rtw

I really am looking forward to getting started that's for sure.

I think you're on the right lines that a full suspension will be overly excessive work without necessarily any sizeable gain in mark.

I am very interested in doing a hard tail, 24" "proper" children's mountain bike at an affordable cost level. The design work has plenty of elements, I could justify a gap in the market and should be able to build a substantial project around this.

Thanks all

Slack hardtail. But really slack. I just slackened mine to 63.5, at BPW it is absolutely bomb proof, climbs well too elsewhere. I dont think the boundaries of slack have been found. Look at some of the BTR vids too. I think the handling relationships between HA, SA, CS and WB are not yet totally exploited! No idea how to build a bike, its just a gut feel. People assume that a long WB slack HT will not handle like a shorter WB more traditional one but, they dont know as they dont exist.

Get it done, change the world!

I'm not so sure about the kids bike thing, kids frame maybe but not kids bike and if you boil it down to frame only then what are you actually looking at as there are already quite a few cheap 24" frames around, they are just in the jump bike market not so much in the mountain bike one which at that size / age I'd argue is an easy enough crossover.

Where brands like Isla bike go into detail (and hence cost) is in the kids components, small bars, small levers and small cranks.

I think, if I am to go down the route more investigation is needed prior to taking that route.

A progressive (and agreesive) geometry hardtail with some nice features such as thru axle, internal cable routing may be the most enjoyable personally, and also the most achievable.

Since it's effectively a design exercise to demonstrate various disciplines and techniques in the engineering process, why not [i]do an HB 211[/i] and disregard the so called industry standards? Take the requirement spec, try and ignore 'standards' and see what you end up with.

It may be hard to justify the market requirement bit but that hasn't stopped Hope!

Probably goes against my last post advising you to keep things simple. I'm just throwing the idea out there!

I certainly agree that going metal Ti, Aluminum or Steel will be the most suitable.

Don't prejudge the output of your analysis! Certainly not on the basis of prototype costs either...

If you are set on making a working prototype, composite could prove beneficial, of course it's a slightly darker art getting an accurate FEA model to work...

Also keep this point from richmars in mind,

The whole process starts with the requirement

Absolutely this! Define your requirements, answer your requirements all too often requirements are poorly defined or not properly addressed...

And I note the brief ties FEA to safety... You'll want to visit the uni library (or use their IHS sub) and get hold of BS EN ISO 8098:2014 - [i]"Cycles Safety requirements for bicycles for young children"[/i] that will probably guide some of your FEA work...

I guess you could look to replicate CEN in your FEA which would give you a base point but I have to say I'm a little underwhelmed with a hardcore hardtail however I'm not grading you so that doesn't really matter.

Proper 24" kids bikes you say?
Spawn have 3 in their range. A DJ bike, a trail hardtail and a full suspension. The dj (kotori) has sliding dropouts for single speed that can be replaced with a d-hanger version for gears. My eldest has the 20" dj set up as a saint/zee 10spd 'do everything' hardtail.
Max at Spawn is a super nice guy and if you are serious about the kids bike route, you'd do well to have a conversation with him. He's the one doing all the product development.
He also has a range of kids specific cranks, forks etc under the brood brand.
[url= http://spawncycles.com/bikes ]Spawn[/url]