Query for you educated bunch of people

Discussion in 'UK and Europe' started by Gadget, May 30, 2003.

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  1. Gadget

    Gadget Guest

    A mate of mine who is studying engineering/mechanics has been set a task by his tutor. He has to
    find something that is in use every day and change it to make it better, than he has to get the
    opinion of a group of people that use that product daily. He decided on trying to make lightweight
    and durable new drive chain out of high impact ABS plastic. This included the cogs and chain and
    everything else used to drive the bike forward. He made and tested this new system and found that by
    removing the metal the bike lost almost a pound in weight. After two weeks of heavy riding he says
    the system is still in good condition. I haven't personally seen the design or the bike. Now he has
    two weeks to get toghter the opinions (which I am doing here) and complete the task.

    So here is his questions.

    1) What can you see being the long term problem?
    2) What can you see being the short term problem?
    3) Would you use it, knowing the weight loss?
    4) Would you use it , not knowing the weight loss?
    5) Your general comments here >>>>>>>>>>>

    I said you were an educated bunch who knew what they were talking about.

    Thanks for helping him in advance.

    Gadget
     
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  2. "Gadget" <[email protected]> wrote in message
    news:%[email protected]...
    >
    > So here is his questions.
    >
    > 1) What can you see being the long term problem?
    How durable would it be, how efficient would it be - eg would any elasticity in the system cause
    power losses (I am reminded of plastic brake levers on cheap bikes which bend rather than transmit
    braking force)...

    > 2) What can you see being the short term problem?
    Same as above

    > 3) Would you use it, knowing the weight loss?
    Not if the supposed problems above exist and not if it made the bike look like an oversized child's
    bike (some of which do have plastic cogs)

    > 4) Would you use it , not knowing the weight loss?
    Same as above

    > 5) Your general comments here >>>>>>>>>>>
    If he's going to ask about supposed problems based on uninformed opinion rather than engineering
    testing, why doesn't he ask about supposed advantages too - eg, one might assume, no rusting, no
    dirty chains, no servicing or lubrication - eg as they say about the Stridabike.

    Rich
     
  3. Nick Kew

    Nick Kew Guest

    In article <%[email protected]>, one of infinite monkeys at the
    keyboard of "Gadget" <[email protected]> wrote:

    > 1) What can you see being the long term problem?
    > 2) What can you see being the short term problem?
    > 3) Would you use it, knowing the weight loss?
    > 4) Would you use it , not knowing the weight loss?
    > 5) Your general comments here >>>>>>>>>>>

    If my (excellent) LBS stocked it, I'd consider it. Marketing and distribution is far more important
    than good ideas.

    But I'd be more concerned by durability and maintenance than weight.

    --
    Axis of Evil: Whose economy needs ever more wars? Arms Exports $bn: USA 14.2, UK 5.1, vs France 1.5,
    Germany 0.8 (The Economist, July 2002)
     
  4. John J

    John J Guest

    > 1) What can you see being the long term problem?
    longevity ( both of the product and the concept), recycle-ability
    > 2) What can you see being the short term problem?
    Compatibility - will it fit?, can I get spares? Confidence, both in it's strength as a component,
    and the market's confidence in a new product - the cycling market is known to be partcularly wary
    of change.
    > 3) Would you use it, knowing the weight loss?
    Probably not immediately. Depends on the trade-offs - cost and above
    > 4) Would you use it , not knowing the weight loss?
    As 3
    > 5) Your general comments here >>>>>>>>>>>
    Weight loss would be even greater on a recumbent presumably :)
    >
    > I said you were an educated bunch who knew what they were talking about.
    >
    I just hope the group doesn't get bogged down in the "It'll never make the High street" attitude -
    Design is about opening peoples eyes to new possibilities by exploring untried alternatives, just
    like 'concept cars'......Sorry, I'll get me coat.
    >
    > Thanks for helping him in advance.
    >
    'Sorite
    >
    John J
     
  5. Anonymous

    Anonymous Guest

    Gadget wrote:

    > 1) What can you see being the long term problem?

    Durability, strength, replacement parts availability, elastic deformation not transmitting power,
    could it be fixed, if it breaks, halfway down a mountain like a chain can, can it run correctly
    under harsh conditions, cold, wet, hot, dry, sandy etc etc probably others if I think hard enough ..

    > 2) What can you see being the short term problem?

    Same as above .. also compatibility, will it work on *my* bike ..

    > 3) Would you use it, knowing the weight loss?

    Depends upon the above problems, but generally yes. For that kind of weight loss it would be worth
    at least trying it. A lot would also depend on the cost. As the whole system would need to be
    changed I wouldn't replace aa already decent system until it was rendered unservicable somehow.

    > 4) Would you use it , not knowing the weight loss?

    See answer to 3 .. Provdiging nothing was 'lost' by changing from metal gearsets then I'd probably
    give it a go ..

    > 5) Your general comments here >>>>>>>>>>>

    Does he have any gearsets to give away as 'trial' systems, and does he want anyone to try it (free
    of charge) 'remotely' .. ;)

    --

    Completed 1725 Seti work units in 13074 hours http://setiathome.ssl.berkeley.edu/
     
  6. On Fri, 30 May 2003 22:16:44 +0100, "Gadget" <[email protected]> in
    <%[email protected]> wrote:

    >1) What can you see being the long term problem?

    Unknown life expectancy

    Ability to change individual sprockets in a cassette? Or would they be cast in a single block?

    Environmental issues? How would a plastic setup be disposed of? Would it be recycleable (excuse
    the pun). Not that i currently worry about how I dispose of metal ones, I'm just being devil's
    advocate here.

    >2) What can you see being the short term problem?

    Compatibility with my existing mechs/shifters etc eg would it use conventional measurements
    (sprocket spacing, length of single chain links)

    >3) Would you use it, knowing the weight loss?

    To me, weight loss would be less important than durability. That's just my style of riding
    (commuting/touring)

    >4) Would you use it , not knowing the weight loss?

    Yes, if it was low maintenance. See (5)

    >5) Your general comments here >>>>>>>>>>>

    I think I would look into using such a design if it required less maintenance than a metal setup.
    I am very lazy: If the plastic system required less frequent cleaning/oiling then I would be
    tempted to use
    it. If metal was more hassle free then I would probably stick with what I already use.

    If somebody can make a bike entirely out of bamboo then I suppose a plastic drivetrain is
    certainly possible!

    Hope this helps

    Love and plastic from Rich x

    --
    Two fish suddenly swim into a brick wall. Damn! To reply put only the word "richard" before
    the @ sign
     
  7. Tim Cain

    Tim Cain Guest

    "Gadget" <[email protected]> wrote in message
    news:%[email protected]...
    > A mate of mine who is studying engineering/mechanics has been set a task
    by
    > his tutor. He has to find something that is in use every day and change it to make it better, than
    > he has to get the opinion of a group of people
    that
    > use that product daily. He decided on trying to make lightweight and
    durable
    > new drive chain out of high impact ABS plastic. This included the cogs and chain and everything
    > else used to drive the bike forward. He made and
    tested
    > this new system and found that by removing the metal the bike lost almost
    a
    > pound in weight. After two weeks of heavy riding he says the system is
    still
    > in good condition. I haven't personally seen the design or the bike. Now
    he
    > has two weeks to get toghter the opinions (which I am doing here) and complete the task.

    I'd love to know how he's managed to integrate this with a cots bike.

    ABS has a tensile strength of ~= 47 N/mm2, while even a rolled mild steel has a strength of ~=
    400 N/mm2.

    To achieve a similar strength using ABS, he's got to scale the chain by about 3.2, to get the
    tenfold increase in x-sectional area.

    This is before you start worrying about the lower elastic modulus of ABS (2GPa vs. 210GPa). This
    will make for a pretty "stretchy" chain.

    How's he done it? Piccies would be nice...

    >
    > So here is his questions.
    >
    > 1) What can you see being the long term problem?

    - Wear, due to the low hardness of the plastic, and it's miserable thermal conductivity.

    - I'd hazard a guess that the plastic drivetrain will not achieve the fabled 95-98% efficiency of
    the standard bicycle drivetrain.

    - Legal action by lots of people who lisp and whistle when they talk due to smacking all their front
    teeth out on the headset.

    > 2) What can you see being the short term problem?

    - Smacking all your front teeth out on the headset.

    - Efficiency, as above.

    - A very elastic drivetrain (ie. ABS) may give a disconcertingly disconnected feeling at the pedals.

    > 3) Would you use it, knowing the weight loss?

    No.

    There is more to a drivetrain than weight, and by focussing soley on this parameter you're hiding a
    multitude of sins.

    > 4) Would you use it , not knowing the weight loss?

    Even more than before, no.

    If I don't know that the ABS drivetrain incurs a weight reduction, I've no reason at all to be
    interested in it, have I?

    > 5) Your general comments here >>>>>>>>>>>

    This has been tried before using Nylon ISTR (on an all-plastic bike). It was not successful. But of
    course your chum will have noted this in his literature review, won't he?

    Cheers,

    Tim

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  8. John J

    John J Guest

    > - Legal action by lots of people who lisp and whistle when they talk due to smacking all their
    > front teeth out on the headset.
    >
    Legal action by lots of people who lisp and whistle when they try to ask for an ABS chainset :}

    John J
     
  9. Anonymous

    Anonymous Guest

    Tim Cain wrote:
    > "Gadget" <[email protected]> wrote in message
    > news:%[email protected]...
    >> A mate of mine who is studying engineering/mechanics has been set a task by his tutor. He has to
    >> find something that is in use every day and change it to make it better, than he has to get the
    >> opinion of a group of people that use that product daily. He decided on trying to make
    >> lightweight and durable new drive chain out of high impact ABS plastic. This included the cogs
    >> and chain and everything else used to drive the bike forward. He made and tested this new system
    >> and found that by removing the metal the bike lost almost a pound in weight. After two weeks of
    >> heavy riding he says the system is still in good condition. I haven't personally seen the design
    >> or the bike. Now he has two weeks to get toghter the opinions (which I am doing here) and
    >> complete the task.
    >
    > I'd love to know how he's managed to integrate this with a cots bike.

    I wonder if he's made a belt drive or shaft drive system instead .. somewhat akin to those utilised
    successfully by BMW for their motorbikes perhaps .. ;)

    --

    Completed 1725 Seti work units in 13074 hours http://setiathome.ssl.berkeley.edu/
     
  10. Tim Cain

    Tim Cain Guest

    "Ian Smith" <[email protected]> wrote in message news:[email protected]...
    > On Sat, 31 May 2003, Tim Cain <[email protected]_know_what_to_cut_timcain.co.uk> wrote:
    > >
    > > ABS has a tensile strength of ~= 47 N/mm2, while even a rolled mild steel has a strength of ~=
    > > 400 N/mm2.
    >
    > Yield stress is more relevant (you woin't be wanting a yielding chain). Construction steel is
    > generally 275 or 355, but there are grades at 185.
    >

    The tensile yield strength of a high rigidity ABS is quoted as 54 N/mm2, so you're scaling by a
    factor of 2 - 2.6 on that score.

    What *are* "standard" chain link side plates made of, anyway? I can't find any links or info.

    > <gadget had previously asked>
    > > > So here is his questions.
    > > >
    > > > 1) What can you see being the long term problem?
    > >
    > > - Wear, due to the low hardness of the plastic, and it's miserable thermal conductivity.
    >
    > Wear is the big problem. Most of my ABS experience is derived from lego, but you get visible wear
    > on axles in a loaded drivetrain relatively quickly - I had a gizmo that rocked my daughter's baby
    > chair, and there was visible wear on components when it got dismantled after a couple of months
    > of occasional use. Add in contamination from road grit and muck, and I don't think it will last
    > that long.
    >

    Yup. And it's floppy.

    Tim.

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  11. Ian Smith

    Ian Smith Guest

    Tim Cain <[email protected]_know_what_to_cut_timcain.co.uk> wrote:
    >
    > "Ian Smith" <[email protected]> wrote in message
    > news:[email protected]...
    > >
    > > Yield stress is more relevant (you woin't be wanting a yielding chain). Construction steel is
    > > generally 275 or 355, but there are grades at 185.
    >
    > The tensile yield strength of a high rigidity ABS is quoted as 54 N/mm2, so you're scaling by a
    > factor of 2 - 2.6 on that score.
    >
    > What *are* "standard" chain link side plates made of, anyway? I can't find any links or info.

    Dunno, I had a quick look for something myself but also found no technical info about the material.

    > > Wear is the big problem. Most of my ABS experience is derived from lego, but you get visible
    > > wear on axles in a loaded drivetrain relatively quickly
    >
    > Yup. And it's floppy.

    I was trying to decide if that'd be a problem. It's more likley to feel odd than to actually lead to
    inefficiency, I think. Of course, it depends how floppy is floppy.

    regards, Ian SMith
    --
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  12. Mark Irvine

    Mark Irvine Guest

    "Gadget" <[email protected]> wrote in message
    news:%[email protected]...
    > A mate of mine who is studying engineering/mechanics has been set a task
    by
    > his tutor. He has to find something that is in use every day and change it to make it better, than
    > he has to get the opinion of a group of people
    that
    > use that product daily. He decided on trying to make lightweight and
    durable
    > new drive chain out of high impact ABS plastic. This included the cogs and chain and everything
    > else used to drive the bike forward. He made and
    tested
    > this new system and found that by removing the metal the bike lost almost
    a
    > pound in weight. After two weeks of heavy riding he says the system is
    still
    > in good condition. I haven't personally seen the design or the bike. Now
    he
    > has two weeks to get toghter the opinions (which I am doing here) and complete the task.
    >
    > So here is his questions.
    >
    Answers
    > 1) What can you see being the long term problem?
    As already mentioned: wear and elasticity. The strength and yeild properties can be increased by
    adding a ballast material, such as glass, but this will also make the material more brittle. Trade
    off as always.
    > 2) What can you see being the short term problem?
    Wear, elasticity, marketting. I cannot see the top end of the market accepting it. It does tend to
    steer away from plastic parts....
    > 3) Would you use it, knowing the weight loss?
    I would want to test ride it first and understand what the wear characteristics were,
    > 4) Would you use it , not knowing the weight loss?
    As above. Also if there were no benefits over the metal system that I use now I would not change. No
    benefits to offset the risk of new technology parts means that I stay with what I know.
    > 5) Your general comments here >>>>>>>>>>>
    There is an excelent book by Mike Burrows on bike design. I seem to recall that he did talk about
    the use of plastic in bike frame manufacture, but was not too hopeful in the near future, possibly
    in the more distant future? It would be worth looking for and would help your friend. Just found a
    reference: Mike Burrows: Bicycle Design, published by alpen books. ISBN: 0966979524 It is out of
    print at the moment, but most of his thoughts are well put forward and very relevent.

    Hope that helps...

    Mark
    <snip
     
  13. Just Zis Guy

    Just Zis Guy Guest

    On Fri, 30 May 2003 22:16:44 +0100, "Gadget" <[email protected]> wrote:

    I guess this is going to be a very "mee-too" kind of response, however as an engineer I would hate
    to discourage another in their studies, so...

    >1) What can you see being the long term problem?

    Wear. ABS will tend to get grit embedded in it and turn into a very efficient abrasive medium - I
    confidently expect the useful life to be not more than a few hundreds of miles (so prove me wrong).

    Yield stress. ABS is less strong than steel, and powerful cyclists have been known to snap
    steel chains.

    >2) What can you see being the short term problem?

    Short term? Shouldn't be many, most things will work for a while. What's he using for lubricant?

    >3) Would you use it, knowing the weight loss?

    Only if wear and strength were not an issue.

    >4) Would you use it , not knowing the weight loss?

    Only if wear and strength were not an issue.

    >5) Your general comments here >>>>>>>>>>>

    I quite like the idea of plastics for drivetrain components, but experience indicates that things
    like plastic cranks and derailleur cages have a very short service life and can fail
    catastrophically, which can spoil your entire day.

    I am looking forward to being proved wrong and knocking the weight of three steel chains apiece off
    two of my bikes :)

    Guy
    ===
    ** WARNING ** This posting may contain traces of irony. http://www.chapmancentral.com (BT ADSL and
    dynamic DNS permitting)
    NOTE: BT Openworld have now blocked port 25 (without notice), so old mail addresses may no longer
    work. Apologies.
     
  14. Hywel & Ros

    Hywel & Ros Guest

    "Gadget" <[email protected]> wrote in message
    news:%[email protected]...
    > A mate of mine who is studying engineering/mechanics has been set a task
    by
    > his tutor. He has to find something that is in use every day and change it to make it better, than
    > he has to get the opinion of a group of people
    that
    > use that product daily. He decided on trying to make lightweight and
    durable
    > new drive chain out of high impact ABS plastic. This included the cogs and chain and everything
    > else used to drive the bike forward. He made and
    tested
    > this new system and found that by removing the metal the bike lost almost
    a
    > pound in weight. After two weeks of heavy riding he says the system is
    still
    > in good condition. I haven't personally seen the design or the bike. Now
    he
    > has two weeks to get toghter the opinions (which I am doing here) and complete the task.
    >
    > So here is his questions.
    >
    > 1) What can you see being the long term problem?
    > 2) What can you see being the short term problem?
    > 3) Would you use it, knowing the weight loss?
    > 4) Would you use it , not knowing the weight loss?
    > 5) Your general comments here >>>>>>>>>>>
    >
    The obvious concerns are
    1) durability - lifetime, resistance to oil, sunlight, water, damage
    2) how it (sooner or later) fails - ie does it suddenly break leaving you stuck far from home
    and / or castrated by the cross-bar, or wear out so you have to replace it - merely a
    matter of cost / hassle.
    3) power losses compared to chain - dry and wet.
    4) What happens if it is out of alignement (ie with a derailler gear)

    My instinct (I'm not an engineer) would suggest that sunlight and oil might be a real problem for
    any plastic, and that the material simply wouldn't be stong enough at all to work as a chain. And
    sudden failure would also be a worry.

    A toothed-belt might work - but then I'd be worried about power-loss. I think sudden failure would
    not be a problem for a toothed belt as end of life "should" be visible. A car cambelt is hidden away
    so you don't see till too late. For comparison certain motorcycles have toothed belt final drive so
    it's tried and tested to some extent. I believe that being out of alignement is a problem though so
    might not work with a derailler system.
     
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