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Thread: Race chassis

  1. #1291
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    21st June 2012 - 14:20
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    I guess that would be termed "Non functional ART"...

  2. #1292
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    10th February 2005 - 20:25
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    1944 RE 1
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    Quote Originally Posted by 190mech View Post
    I guess that would be termed "Non functional ART"...
    Just keep studying it for a couple of months and it'll probably grow on you as your mind adjusts maybe? - (Yes I reckon just taking the piss and seeing where it might end up).
    Picasso I'm told acknowledged that his own art didn't follow the rules imposed by society and to the average person it was crap, but he still made a very good living from it!
    Harley Davidsons sell too! - in fact, the big boys copied them (ie their image) more or less.
    Freedom of speech is important but if what we say is incorrect, our peers will quickly put us right.
    P.C. will eventually destroy our right to tell the truth.

  3. #1293
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    18th March 2013 - 04:44
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    Bike from the beginning of this thread is for sale here https://www.racebikemart.com/adverts...1265102316.php

  4. #1294
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    28th November 2013 - 21:58
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    1965/68 Tribsa 500
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    No idea if this is any good, the only apples I have access to are Bramleys and Lord Lambournes. It's an app for fork seals, found it while looking for something quite different.
    http://www.skf.com/uk/knowledge-cent...T.z_oss_rank=1
    Just noticed it says uk in the link, too. Maybe just go to skf.com and search for "bike seals".

  5. #1295
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    19th October 2014 - 17:49
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    whatever I can get running - dirt/track/
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    Triumph with plywood monocoque and a balancing system somewhat like that of a Buell (or MZ). From BIKE magazine. About 1.5 mb on the PDF
    Attached Files Attached Files

  6. #1296
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    13th June 2010 - 17:47
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    Finally got a read of that wooden monocoque article. He's right about having done it the hard way. There's a long history of boatbuilding in my family - incl cold moulded laminates - and if you want them, double curvature panels are quite easy. Even single thickness ply sheets can be bent to double curvature - I well remember the effort required with our last keeler build where 3/8in sheets had to be curved two ways...
    A small - bucket size - monocoque on similar lines to the "Bultaco" 50 would be comparaitively easy. Straight sides and a bag tank. Fabricated load points glued and screwed in.

    Could be a problem at Greymouth though - you'd need to anchor it in the pits if it was the usual wet meeting....
    Reason is a tool - remember where you left it..... The late, great, John Clarke

  7. #1297
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    28th November 2013 - 21:58
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    Apart from aesthetics, I’m not convinced you’d want the complication of curved panels. Some scantling rules allow you a reduction in skin thickness for curved panels but that’s more about deflection of a boats skin. Would it make any difference to the overall stiffness of a bike frame? I doubt it, personally, but anyone who wants to have a go try googling “constant camber” or “cylinder moulding ”. If they turn out to be too vague try adding “boat”, “catamaran” or “trimaran”. Also, the book “The Goudgeon Brothers on Boatbuilding ” was available as a free (legit!) download which is kind of the bible of modern wood epoxy boatbuilding. I’m on my phone in the middle of nowhere so can’t provide links at the moment.
    For an idea of just how far ply construction can be pushed try looking up sailing dinghies – the Inernational Moth or Cherub.
    More relevant to bikes would be researching Frank Costin and Marcos or, possibly, Africar.
    If, like me, you’re still in the stone age and don’t do FEA etc. You could try working from known examples. To convert from one sheet material to another of equal stiffness I use the formula of dividing the Youngs modulus of the old material by that of the new, then the cube root of the answer gives you the conversion factor. Apologies for the next bit, but I started out doing this stuff in imperial units and they are the ones I can recall.
    All steels, from plain to fancy, are the same stiffness with an E (youngs modulus) of about 30000
    I think there’s more variation in Ali but for the boatbuilding ones it’s about 10000.
    Plywood is quoted variously as 1600 - 1800. I use 1500 and round up to the next actually available thickness as other factors like puncture resistance come into play for boats.
    If that makes ply look like a non-starter, do the sums for Frits 2mm steel battleship of a monocoque and you would be looking at 6mm ply which would be a LOT lighter. Which is why Frank Costin started building wooden chassis cars...
    You could go further and copy the De Havilland Mosquito. Birch ply is available in very small thickesses so the possibilities of a sandwich construction would be almost infinite.
    That would seem only fitting as I believe there was a massive amount NZ involvement in the Mosquito and some of the world’s most cutting edge wooden boats come from there.
    The other obvious way to use ply would be in a Tony Dawson style plate frame (very first picture in this thread?). I’ve actually built something like this, with 2 wheels and an engine... but it also had a propellor :-)
    There are wooden bicycles of various sorts, too.
    Sorry to ramble on so much, but I was supposed to be at the Bemsee open day at Brands Hatch, today, sorting out racing for next year and I’ve ended up on “stake out” outside a village hall craft fair so quite bored!
    One final (hurray!) thought. Greg posted the excerpt from Mike Sinclair’s book about why carbon fibre frames weren’t that great so I probably just wasted your time, too!
    Last edited by guyhockley; 11th December 2017 at 03:32. Reason: changed equal stitches to equal stiffness

  8. #1298
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    28th November 2013 - 21:58
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    Sorry if I've insulted/patronised, upset anyone or got my facts wrong, but, out in the sticks and bored. (Did I mention that?)

  9. #1299
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    19th October 2014 - 17:49
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    Here's the boat book

    https://www.westsystem.com/the-gouge...-construction/

    https://www.westsystem.com/wp-conten...k-061205-1.pdf

    I was coming up with 1/16" sheet steel having similar stiffness (but more weight) than 3/16-1/4" baltic birch plywood, so that seems to track Guy's numbers. I wasn't able to find much detail on the Marcos chassis on the web. I think I saw a mention of them using Araldite 300

    https://us.aralditeadhesives.com/ind...id=146&lang=us

  10. #1300
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    28th November 2013 - 21:58
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    Quote Originally Posted by Michael Moore View Post
    Here's the boat book

    https://www.westsystem.com/the-gouge...-construction/

    https://www.westsystem.com/wp-conten...k-061205-1.pdf

    I was coming up with 1/16" sheet steel having similar stiffness (but more weight) than 3/16-1/4" baltic birch plywood, so that seems to track Guy's numbers. I wasn't able to find much detail on the Marcos chassis on the web. I think I saw a mention of them using Araldite 300

    https://us.aralditeadhesives.com/ind...id=146&lang=us
    The book is still available, then. There were chancers on Amazon still trying to sell hardback versions for way above the new price even after it was made available free. Sadly, the book about Frank Costin also seems to be in the collectible category.
    https://www.amazon.co.uk/Flying-Four...s=frank+costin
    Good read, at one point IIRC they built a single seater for an american customer but had to disguise the wooden monocoque by "cladding it in very thin aluminium - almost tinfoil" I think was the quote. Unfortunately he crashed it...

  11. #1301
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    13th June 2010 - 17:47
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    Some years back, I walked into a friend's workplace - and there was a Marcos up on the hoist. Very interesting to study the linked boxes making up the chassis. I've also seen a Protos single seater. It turned up here for one of the big classic car race meetings. Interesting. McLaren's first F1 car was built from a part-wood sandwich composite too - Mallite ?
    It's certainly a viable material for the home constructor. Cheaper than alloy sheet, probably a tad more robust re dents etc....And you could jig one up on a Black and Decker workmate table...

    I always understood that the Mosquito ply construction was pioneered by DH Canada. I do know there's one being rebuilt hopefully to flying condition here in NZ so I'd guess that most of the current references on the net refer to that one.
    Reason is a tool - remember where you left it..... The late, great, John Clarke

  12. #1302
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    20th April 2011 - 08:45
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    Quote Originally Posted by guyhockley View Post
    To convert from one sheet material to another of equal stiffness I use the formula of dividing the Youngs modulus of the old material by that of the new, then the cube root of the answer gives you the conversion factor. All steels, from plain to fancy, are the same stiffness with an E (youngs modulus) of about 30000. Plywood is quoted variously as 1600 - 1800. If that makes ply look like a non-starter, do the sums for Frits 2mm steel battleship of a monocoque and you would be looking at 6mm ply which would be a LOT lighter.
    I didn't know this (along with a lot of other things) when I designed my steel monocoque in 1972. But even if I had known, there was one good reason to stick to steel:
    I didn't know how to weld plywood. I still don't.

    I don't doubt your stiffness comparison either, but I had no use for more stiffness in view of the skinny fork tubes, the spoked wheels and the threaded tires, all acquired second- or third-hand.
    As it was, I think I already had the stiffest 500 cc frame at the time, and it was also the smallest, lowest, narrowest, lightest and most unreliable bike in its class.
    And it was sooo easy to build: cut some 2 mm mild steel sheet, fold it, weld the bottoms in, that was it.
    FOS monocoque.png 1973 FOS 01.jpg fos-Bultaco 1972.jpg

  13. #1303
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    20th January 2010 - 14:41
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    Quote Originally Posted by Grumph View Post
    Some years back, I walked into a friend's workplace - and there was a Marcos up on the hoist. Very interesting to study the linked boxes making up the chassis. I've also seen a Protos single seater. It turned up here for one of the big classic car race meetings. Interesting. McLaren's first F1 car was built from a part-wood sandwich composite too - Mallite ?
    It's certainly a viable material for the home constructor. Cheaper than alloy sheet, probably a tad more robust re dents etc....And you could jig one up on a Black and Decker workmate table...

    I always understood that the Mosquito ply construction was pioneered by DH Canada. I do know there's one being rebuilt hopefully to flying condition here in NZ so I'd guess that most of the current references on the net refer to that one.

    Whats wrong with Bamboo
    Natures tube.
    there are guys making MTB frames with it instead of CF it has a better ride according to them.
    http://www.instructables.com/id/How-...ome-and-a-bam/
    http://www.shopcalfee.com/calfee-bam...-small-sb0422/
    It was good enough for Dick.
    https://en.wikipedia.org/wiki/Richard_Pearse

    The Mosquito also had a very small radar signiture it was stealth before it was even thought of......
    Most don't realise it could also carry a bigger bomb load further and a dam sight faster than a B-17 could.
    More research required...

    Kinky is using a feather. Perverted is using the whole chicken

  14. #1304
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    28th November 2013 - 21:58
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    Quote Originally Posted by Frits Overmars View Post
    I didn't know this (along with a lot of other things) when I designed my steel monocoque in 1972. But even if I had known, there was one good reason to stick to steel:
    I didn't know how to weld plywood. I still don't.

    I don't doubt your stiffness comparison either, but I had no use for more stiffness in view of the skinny fork tubes, the spoked wheels and the threaded tires, all acquired second- or third-hand.
    As it was, I think I already had the stiffest 500 cc frame at the time, and it was also the smallest, lowest, narrowest, lightest and most unreliable bike in its class.
    And it was sooo easy to build: cut some 2 mm mild steel sheet, fold it, weld the bottoms in, that was it.
    FOS monocoque.png 1973 FOS 01.jpg fos-Bultaco 1972.jpg
    Oh, dear. I wasn't being rude about your frame, I used it as it had been posted on the thread, you told us the material and its beautiful simplicity made it an easy example. I ignored the question of joining the panels and if the epoxy saturation techniques in the book were followed it would also add significant extra weight.
    I actually think your frame would make a perfect engineering textbook study.
    Improves on the previous model/competitors, simple, fast and cheap to make requiring no new techniques or tooling and probably could be as good today as when it was built unlike the rivetted ali monocoques which I believe go a bit floppy!
    As I feel I've upset you (and Husa) at least a couple of times, I'm going to take a metaphorical back seat and let people with more knowledge and experience than me continue my (free!) education.

  15. #1305
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    20th April 2011 - 08:45
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    Quote Originally Posted by guyhockley View Post
    Oh, dear. I wasn't being rude about your frame.... I feel I've upset you (and Husa) at least a couple of times....
    I haven't seen anything rude at all. I'm not upset that easily and I've never even sensed any intent from your part. So no worries Guy .

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