Bike Design No.1

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May 23, 2012, 05:47:37 PM

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[domino0]

Right all, the first one...........

Its called the "Squash"
Its a DH bike with around 8-9" of travel (image not to perspective)
(Nothing to Scale)

This is one of the ones where a little more thought needs to come into play, whether to have a pivot at the rear or not! But having thought about it i do not believe there is need for one and it would much it all up!

Full bike image:



Detailed image:



Comments, next image will appear in the nest few days as bike design no2

[fly6154]

what tyres you running

[domino0]

Those will probs be maxxis 

[steveb]

To be fair, I can't take this seriously, but...

It's a single pivot. It's got lots of pivots but most don't do anything. It's a single pivot. With an incredibly long shock of which about ten percent of the stroke is used. If it's got the travel you say the shock ratio is about 20:1, slightly higher than the standard of about 3:1. You'll need about a 2000lb spring which will need to be custom made, so will the shock as it looks like it has an I2I of about 800mm.

The pivot position (the  only pivot that actually does anything) is too high, the bike will suffer more pedal feedback that a Y frame Trek. The rear mech will need to be ultra long cage to manage the ultra long chain the bike will need to stop it snapping at max travel.

Unless the rear end is made of solid rods it'll flex like a very flexy thing.

My only question is what are you doing? Seriously, my kids (8 and 10) do stuff like this. How old are you? Do you have any understanding of how and why suspension does what it does? My advice is stop wasting time on drawing pictures  and spend it reading engineering and suspension papers. If your serious you need to study this stuff before putting pen to paper. If your the age of my kids and doing this for a school project, crack on, maybe get the crayons out and colour it in too.

;-)

[domino0]

Thanks a bunch Steve, as i said in the previous post, it wasnt meant to be a pectacular fantastic drawing, more just looking at different ways suspension could work, or work with the frame (if you know what i mean), and i also mentioned tht nothing was to scale!! Plus no more pivots than a V10 or similar

[fly6154]

lighten up steveb,give the lad a chance its his first attempt

[Vic-Tim.com]

Unfortunately playing around with pivot points is only half the story.

You need need to get yourself some squared paper and work to scale...otherwise you will always get an impossible set up.

Also consider what has actually been done. Do you know the difference between Four bar and Faux bar? Can you explain VPP or the DW link?

And rememeber this is a forum and there are some cynical b'stards on here ( including me sometimes ).

In conclusion...more homework needed me thinks.

Tim S

[domino0]

I know about all these different linkages but as far as i can remember (which isnt very much) there as not been any of these design linkages or watever you want to call it on a frame designed like tht. Plus i have no squared paper and ive done quite a few now and there is no point changing, i know nothing is to scale but thts not wat im after here. Plus i will stress:

IT LOOKS DIFFERENT ON A SH!IT PICTURE TAKEN AND POSTED ON A FORUM THAN IT DOES ON PAPER

Plus these are my special ones, i BELIEVE ( AS FAR AS I KNOW) designed linkage of my own, it compresses from both ends, only for DH/FR bikes. Dont know the advantages though!

[steveb]

OK, I'll redo my reply, in a light and fluffy way.

Look carefully at the design, the shock connects  to the swingarm about 2" from the main pivot, between these two points are no other pivots, also there are no other pivots between the BB and the rear wheel axle, therefore, it's a single pivot. The upper linkages serve no purpose. These things don't need to be to scale, just thought out more.

What you've done is not design a new platform, or started to create a new platform, you've taken two visual features of existing designs and put them together so to the passing eye it looks like it'll work, but dig a bit and it won't, it just won't, even to scale it won't.

OK, not very fluffy, but what is the point is saying what you want to hear? If you want to take things further and start producing designs that at least on paper might work, you need to be hearing things straight.

First thing you need is a goal. When Commie set out to design a new platform they spent ages working out what they wanted from the design. They decided they wanted their bikes to be the fastest. Next they worked out what would make their bikes fast. They concluded grip. They worked out the more grip a bike has the faster it can go off road. Then they set about designing the contact system.

If you want to do the same, you need to start at the beginning. First decide what you want your design to achieve. Then play with your own bike, talk to riders and work out how to achieve this. Then put pen to paper.

If you want to do this seriously, it's the only way forward. it'll be hard work, and take years, but you might just design the next contact system. Draweing pictures now might give you some sort of immediate gratification, and there is nothing wrong with that, but it'll never lead anywhere. Snd if you put them out there for public comment, your going to get some grunpy fucker ripping them to shreds ;-)

[Snakes]

there as not been any of these design linkages or watever you want to call it on a frame designed like tht.

There is probably a reason for that. In my opinion you are starting at the wrong and. Every millimeter counts, when we are talking about suspension design. There are done serious calculations, it is not that someone draws something and then they test it. Read some interviews with suspension designers, it is not hard to find them on internet. Only on Bikeradar I can remember of at least three, it is interesting reading.

[bong69uk]

Hmm any1 else think that Steve has been having a few rough days at the office?? he seems a bit emotional lately 

[steveb]

LOL, just tired lately. Work is pretty stressful nowadays, but no worst than it is for most working folk, but I've been flat out in my garden the last while, every spare moment spent putting in the last push to get it finished from 3 years on on going work.

If you need any pointers on decking, I'm your man. Done over 500sq ft of it lately, on me own!

First full weekend off in months coming, party on Saturday and riding Sunday, so should be back to normal next week. but that drawing will still be the same then though ;-)

[iain1775]

Hmm me thinks our admin are getting revenge for the negative response to the 'exclusive 2010 posts'
Constructive crititsm - which this definately is - is very good and helpful - but not always tactful  

So Dom is doodling instead of revising for exams, at least he is showing an interest in Mechanics and Engineering, and thinking about things (perhaps not correctly, but without years studying mechanical and dynamics etc at Uni who does?) if he can turn his hobby and his passion into a successful career then surely that is good and should be encouraged, if im not mistaken he as at that age where you are at school and being forced to make life altering decisions on what you want to do with the rest of your life. Don't knock him for it, it may be early days but we could be looking at the next Dave Weagle here. If not havent we all doodled innocently at some point?

Keep it up Dom, like Steve says do some reading and research, keep studying and most of all riding because the best ideas often come from your own experiences rather than a text book

I might also post my sketches soon - trust me that will take it back to the basics and really reinvent things, forget all these 29" wheels, 69ers, Sram XX 10 speed etc - anyone fancy an off road hardtail carbon fibre penny farthing with 6" of front suspension, adjustable seatpost and disc brakes?

[iain1775]

If you need any pointers on decking, I'm your man. Done over 500sq ft of it lately, on me own!

ahh but did your missus insist on ROUND decking???
Mine did - let me tell you that is a ball-ache - Needs an octagonal subframe only slightly smaller than the radius of the final deck, need to ensure your decking planks are cut right so you dont end up with unsupported bits where the subframe isnt the same shape as the deck and jigsawing the final circle shape is really good fun

Never mind though Steve will be worth it when you have a nice large area to carry out bike repairs and cleaning at home rather than using the shop 

[Steve UK]

Right all, the first one...........

Its called the "Squash"
Its a DH bike with around 8-9" of travel (image not to perspective)
(Nothing to Scale)

This is one of the ones where a little more thought needs to come into play, whether to have a pivot at the rear or not! But having thought about it i do not believe there is need for one and it would much it all up!

Full bike image:



Detailed image:



Comments, next image will appear in the nest few days as bike design no2

From looking at these drawings you do not have a clue on how suspension works, you do however have a bit of artistic flair with a curious eye to the engineering side.

When designing a new suspension platform performance and packaging would come first, then maybe making it look pretty.

On one of your drawings it was obvious one of the leading chain devices may not fit, remember these things also have to be taken into consideration.

Another point is that suspension designs are designed around a chainring size as this has an impact on suspension performance.

There are so many factors you need to consider, I suggest you pick your subjects carefully at school. eg maths, physics, chemistry, English, art?

Best of luck