I've touched the C'dale Super V4000

I've touched the C'dale Super V4000

Post by Mark VandeKa » Sat, 11 Dec 1993 07:46:34



Quote:
>right now, since the show bike weighted 70+ pounds, as it was a solid chunk
>of aluminum and not CNC-hollowed like it's planned to be.
>I'd be willing to bet that Outside hasn't ridden
>the bike at all, and are only telling what the designers boasted to them.
>I heard from a friend who went to the Interbike show that the bike is really
>quite a long ways from actual production.  Now, maybe since Alex Pong is
>not a typical bike-industry guy his time-to-production is much less, but
>I'm betting that Outside is just trying to show a crack at the future, and
>not actually reviewing the bike.

You are right, Bill.

I have both read the Outside article and seen the bike in question (I went
up to Magic Motorcycle's shop and took Skooks Pong out to lunch).  The
bike was (at interbike and when I visited the shop a few weeks later) a
mix of production ready pieces and solid aluminum chunks.  The Outside
article is NOT a review of the bike (which also lacks essential parts like
disc brake calipers and suspension mechanisms), but is a fairly balanced
description of the Pong/Cannondale cooperation.  The article matches my
impressions in describing the bike as a very original and jewel-like piece
of equipment.  But also subtly raises some questions about such things as
why it uses 12 aircraft-quality bearings that cost $90 apiece.  I guess if
you're going to build a flagship model you go all out, but there are other
places on the bike where a lot of cost and effort go into seemingly small
improvements.  The thing I noticed was that the wheel retention mechanism
was really slick -- one torx***acts on a lever and clip system that
grabs and holds the hub.  However, the mechanism appeared to be made up of
at least 10 very small pieces, each of which is CNC machined.  How much
is too much?
        I'm not sure the bike will be shipped in the spring, but I think
it will reach production much faster than a typical show-bike prototype.
The unique thing about the Pongs is that their prototypes are not
hand-made -- They are CNC machined.  That means that the piece is ready to
manufacture by simply running the programs again after putting a fresh
block of aluminum in the machine.  The manufacturing is facilitated
because they design within the capabilities of their CNC machine and try
to avoid non-standard tooling (i.e., special size or shaped cutting bits).
It's not like a system where the design crew comes up with something and
tells the manufacturing guys, "Here.  Figure out how to make this." The
Pongs, until they teamed with Cannondale, were both the design and
manufacturing guys and they are retaining the resulting philosopy of
design.  Skooks told me that this integration was one of the key things
that made Cannondale interested in the partnership.
        The other possible failing of the project is that the Pongs work
almost exclusively in aluminum.  I think they do incredible things with
the stuff, but I wonder if other materials might better fit certain
applications.  Perhaps the best example is the body of the bike.  It seems
to me that the most advanced work in monocoque construction right now is
probably in F1 racing, and composite materials seem to be the choice
there.  Would a carbon fiber X-shaped frame like the Trimble mountain bike
I saw in a magazine some months ago (sorry, but I forgot which and when)
work better than the bonded aluminum shells the Pongs are fabricating?
        I can't say that I think the future of bicycles rests in the hands
of Cannondale and the Pongs, but I think it's good for the field to have
people out there pushing the envelope.  I also think that whether or not
one thinks the endeavor will be successful, anyone who closely examines
the bike will be impressed with the originality, precision, and quality
of the pieces.  I wish I had had more time to ogle the thing myself.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Mark Vande Kamp              |  Probably the earliest flyswatters were nothing

                             |  attached to the end of a long stick.
                             |  -- Jack Handey
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 
 
 

I've touched the C'dale Super V4000

Post by Naruhisa Takashi » Sat, 11 Dec 1993 23:19:38

Although the frame is eye catching, I personally think it's really no big
deal.  Other people and companies have built it before, and the motorcycle
industry has been using it for years.  I agree w/ the previous poster
that carbon graphite might be a great alternative for the frame material.

What I think the bike's greatest contribution is the way the suspension
system is linked.  By aligning the chain w/ the swing arm, the pedaling
motion should not induce motion in the swing arm.  One thing I am curious
is how it damps. An article I read said that it has coil spring
mechanism.  That's fine for absorbing the shock, but how do you damp the
rebound?

I also think that the use of same bearing throughout the bike is simply
an overkill.  There is no need to have the same bearing in the BB and the
headset.  Unless you take the bearings apart every week or so, it just
doesn't make sense to have same bearings throughout the bike.  
Especially since sealeds cartridge
bearings are readily available and they require far fewer maintenace than the
traditional bearings.

Lastly,  I'm curious as how the wheels are made.  From appearance it
looks like it'll weigh a ton!  I wonder if the wheels are hollow and
made out of magnesium or something.

I personallu think Pong can reduce the weight in the frame easily, but
in order to get the weight of the bicycle to 20 lbs he would have to
change the wheel and the bearings.

What do you think?

Naru Takashima

 
 
 

I've touched the C'dale Super V4000

Post by bui tho xu » Sat, 11 Dec 1993 14:42:39


Quote:
>You may be right, the $90 dollar figure I quoted was from the Outside
>article, not from Skooks Pong.  At $20 per, the ability to use one size
>of bearing for everything in the bike makes more sense.

I find this interesting.  This bearing is design for both rolling
(hubs, cranks) and thrust (headset) loads?

Quote:

>>Well, technically the V4000 isn't monocoque or bonded.  Actually, it's totally
>>screwed up (literally!)  The frame is made up of "clams" that***together
>>with Torx screws.
>The last time the net debated what was/was not a monocoque the consensus
>seemed to be it was a structure that distributed stresses through its
>skin.  The V4000 certainly fits this description.  The question might be,
>what bicycle frame does not?

The last time we discussed the term, I believe Harry Phinney gave the
definition of monocoque--the original definition, which applies to
aircrafts.  Before the days of monocoque construction, airplanes were
built-up with struss-works from tubings and then covered with cloth\
and other materials.  Later on, the covering take over the load carrying
responsibility, and the term monocoque was born (actually, most
aircrafts are built with a mixed mode, semi-monocoque construction).

Since the upright safety bicycles have no covering, the term monocoque
has no real technical value.  Kestrel is probably the first to use
it for marketing purpose, since their design is different from the
the standard tubed bike.  But it really isn't a monocoque, because
the struts are still there, just no longer in constant diameter tube
form.  Until the bicycle completely encloses the rider with a shell that
carries the loading, the term monocoque will remain improperly used.

But hey, if it sells bike, who cares?

tho

 
 
 

I've touched the C'dale Super V4000

Post by Felix K » Sat, 11 Dec 1993 12:53:18

|> But also subtly raises some questions about such things as
|> why it uses 12 aircraft-quality bearings that cost $90 apiece.  I guess if
|> you're going to build a flagship model you go all out, but there are other
|> places on the bike where a lot of cost and effort go into seemingly small
|> improvements.

Yup, the bearings are expensive all right, but each 2.5-inch bearing costs
only $20 according to the Winning December issue (that is, if my memory
serves me right!  My copy of Winning is in a picture frame in my room
right now because Lance Armstrong signed it!  :-] )  Also, the bearings in
the headset, hubs, and bottom bracket are all the same and interchangeable.
Alex Pong claims that there are too many different bearings in today's bikes
that are too small and hard to service.

I suppose if I were to pay $5-7000 on a bike, I would want such attention
to detail.  (Of course I wouldn't pay that much for a bike, however -- I
would buy 1 or 2 MG's! :-]  I'm digressing)

|> The thing I noticed was that the wheel retention mechanism
|> was really slick -- one torx***acts on a lever and clip system that
|> grabs and holds the hub.

This brings up another point -- one-size torx screws are used exclusively
on the Cannondale V4000.  I think this is a great idea!  A V4000 owner would
only need one torx wrench (a modified version of an allen wrench) to
disassemble the bike.

|>   The other possible failing of the project is that the Pongs work
|> almost exclusively in aluminum.  I think they do incredible things with
|> the stuff, but I wonder if other materials might better fit certain
|> applications.  Perhaps the best example is the body of the bike.  It seems
|> to me that the most advanced work in monocoque construction right now is
|> probably in F1 racing, and composite materials seem to be the choice
|> there.  Would a carbon fiber X-shaped frame like the Trimble mountain bike
|> I saw in a magazine some months ago (sorry, but I forgot which and when)
|> work better than the bonded aluminum shells the Pongs are fabricating?

Well, technically the V4000 isn't monocoque or bonded.  Actually, it's totally
screwed up (literally!)  The frame is made up of "clams" that***together
with Torx screws.  The frame is designed such that it can be disassembled
(unscrewed apart) to fit in a suitcase.  Another great idea!  

Personally I love aluminum (and my Cannondale 3.0 Road) but let's not start
another which-material-is-best war!  Oh, BTW, did anyone see the C'dale
Silk Road with Headshok suspension?  Silk Roads are equipped with Mavic Zap
and Campagnolo Ergopower!  (Ergo is used to adjust the front suspension
on-the-fly).  Any additional comments/info/observations/flames?

-Felix

 
 
 

I've touched the C'dale Super V4000

Post by David Kepp » Thu, 16 Dec 1993 09:42:53

Quote:
>>[Pong-designed Cannondale full-suspension bike.]

>[I am impressed by the aligned chain and swing arm, where pedaling
> (chain tension) does not induce swing arm motion.]

Drivetrain efficiency, however, may be a problem.

The Pong design, for those who haven't seen the photographs, uses an
arm along one side of the wheel.  The arm has a pivot "about" half way
between the crank axle and the wheel axle, and the spring and shock
are mounted at that pivot.  The "slack" side of the chain runs
normally from derailleur cage to the underside of the chainwheel.  The
taut side runs from the chainwheel, over a strategically-placed idler
wheel (idler == changes the chain direction but the shaft does not
transmit power) and down to the rear cluster.

The idler eliminates suspension bobbing induced by varying chain
tension, because the idler ensures the chain always passes through the
center of the pivot point.  If the chain were below the pivot, a taut
chain would pull the arm down (elevated chainstay designs like the
Pro-Flex and Cannondale).  If the chain were above, it would pull the
arm up (Miyata, Marin).  With the chain running through the middle of
the pivot there is no torque.

Although the coincident idler is a well-known fix in other domains, it
hasn't generally been used in suspension bicycles.  I hazard that it
is because of drivetrain efficiency.

A chain loses power every time it is flexed under tension.  In a
normal bicycle drivetrain this happens when the chain "unwraps" from
the rear cogs and when it "wraps" again over the front chainring.  The
normal figure I hear is 1/2% per wrap/unwrap for a clean
well-lubricated chain running in a straight line.  (Silent chains used
for timing belts and old Cadillac transmissions have rolling rather
than sliding surfaces and thus have better efficiency; these designs
don't tolerate misalignment and thus do not work in derailleur
applications.)  With the idler design (such as that used by Pong), the
taut side of the chain goes through an extra wrap/unwrap, so, ignoring
other losses, the efficiency of the transmission is halved.

I do not know of any controlled studies with "good hard numbers" for
derailleur drivetrain efficiency with changing angle (but see the
recent Cyclopedia catalogue; it looks that efficiency drops
drastically with misalignment) and as the chain loses lubrication and
picks up dirt (I hazard the efficiency is far worse than for a clean
chain) and the efficiency is not a fixed number like 1/2% per
bend/unbend but actually depends on the size of the gear that the
chain is wrapping.  These factors make it hard to predict the
efficiency of a drivetrain with an idler, but at best it will always
be about 1% worse than a traditional drivetrain and for a dirty chain
without proper lubrication (such as you might encounter on rides for
which the bike is designed) it could easily be far worse.

There are some other considerations as well.  For example, the extra
chain wrapping and unwrapping at the idler increases both friction and
wear.  On the other hand, the idler can be made to "float"
side-to-side so that the chain line is no worse than on other bikes,
and the derailleur can keep the same orientation relative to the
swingarm, so the number of teeth of engagement is the same.

What this all means for an average rider is unclear, but even in a
good scenario, the drivetrain is 1% less efficient than a conventional
system.  If rider+bike is 100kg, cutting 1% from the efficiency is
like adding 1kg to the bike on every hill climb.  In a bad scenario,
the drivetrain is 5% less efficient, corresponding to 5kg on every
hill climb!  Furthermore, the idler design is not the only way to cut
bounce (Fisher) , and even with the idler design the pedaling motion
of the rider causes some bouncing, so the idler design is not a
`magic' cure.

Will the benefits outweight the costs?  Derailleur gears add weight
and cut efficiency but are still worthwhile.  But nobody has ridden
idler designs recently, so only time (and testing) will tell if an
idler helps more than it hurts, or whether the loss in efficiency
and increase in wear leaves the idea as just another good idea.

        ;-D on  ( Where efficiency is a concern )  Pardo

 
 
 

I've touched the C'dale Super V4000

Post by Mark VandeKa » Sat, 11 Dec 1993 14:03:52

Newsgroups: rec.bicycles.tech
Subject: Re: C'dale Super V4000
Keywords: Super V4000, Magic Motorcycle, Cannondale

Quote:

>Yup, the bearings are expensive all right, but each 2.5-inch bearing costs
>only $20 according to the Winning December issue (that is, if my memory
>serves me right!

You may be right, the $90 dollar figure I quoted was from the Outside
article, not from Skooks Pong.  At $20 per, the ability to use one size
of bearing for everything in the bike makes more sense.

Quote:

>|>       The other possible failing of the project is that the Pongs work
>|> almost exclusively in aluminum.  I think they do incredible things with
>|> the stuff, but I wonder if other materials might better fit certain
>|> applications.  Perhaps the best example is the body of the bike.  It seems
>|> to me that the most advanced work in monocoque construction right now is
>|> probably in F1 racing, and composite materials seem to be the choice
>|> there.  Would a carbon fiber X-shaped frame like the Trimble mountain bike
>|> I saw in a magazine some months ago (sorry, but I forgot which and when)
>|> work better than the bonded aluminum shells the Pongs are fabricating?

>Well, technically the V4000 isn't monocoque or bonded.  Actually, it's totally
>screwed up (literally!)  The frame is made up of "clams" that***together
>with Torx screws.  The frame is designed such that it can be disassembled
>(unscrewed apart) to fit in a suitcase.  Another great idea!

The last time the net debated what was/was not a monocoque the consensus
seemed to be it was a structure that distributed stresses through its
skin.  The V4000 certainly fits this description.  The question might be,
what bicycle frame does not?  I don't think either of us is in a postion
to determine if the main frame sections will be bonded or screwed
together.  When it was exhibited, and when I saw it, these were the parts
that were solid aluminum.  Certainly each hollow section will be screwed
to the others (you can see that from the pictures) and these sections
could be easily disassembled for transport as you point out.  I do know
that the front fork/swingarm, wheel spokes, and rims are made of hollow
shells bonded (i.e., techese for glued) together.  

Quote:
>Personally I love aluminum (and my Cannondale 3.0 Road) but let's not start
>another which-material-is-best war!

Actually, I love aluminum (and MY Cannondale 3.0 Road) as well.  I was
just trying to raise a question about the possible drawbacks of
working in only one material.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Mark Vande Kamp       | When they hatch, certain marine invertabrates must

                      | their days.  For this purpose they have a
                      | rudimentary brain.  Once they attach, the brain is
                      | no longer necessary so they eat it.  
                      | It's sort of like tenure.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 
 
 

I've touched the C'dale Super V4000

Post by armin karch » Fri, 17 Dec 1993 03:33:58

 Pardo writes :

  Drivetrain efficiency, however, may be a problem.

  The Pong design, for those who haven't seen the photographs, uses an
  arm along one side of the wheel.  The arm has a pivot "about" half way
  between the crank axle and the wheel axle, and the spring and shock
  are mounted at that pivot.  The "slack" side of the chain runs
  normally from derailleur cage to the underside of the chainwheel.  The
  taut side runs from the chainwheel, over a strategically-placed idler
  wheel (idler == changes the chain direction but the shaft does not
  transmit power) and down to the rear cluster.
[Deleted lots of good stuff]

Well in HPV racing pivots are used quite often (with clean chains).
The Vector (Germany) racing team claimed their two idler design cut
1% of efficiency. (remember, fully faired bike, no dirt on chain)
They had an older idler design that cut 5% (two idlers, similar angle)
the basic change was that in the new design they used a teflon sprocket,
with the chain running in a grove rather than on teeth.
In HPV designs the chain is so long that sidewise missalignment is no
problem.
On a MTB this will be THE biggest problem. As the original poster said
you could give the idler float, so the worst flex is eliminated, the
chain will still cross the idler at an angle causing considerable loss.

I do not know of a solution that eliminates bounce (could the original
poster enlighten me?), but I do think that a idler design is very far
from ideal.
If the chain runs less than an inch from the pivot, bounce is not comon.
The pivot should be closer to the chainline in small climbing gears.

For all who wonder why the Vector team uses two idlers: The frontal area
was reduced by 10%, so speed increased by 9%.

Armin

 
 
 

I've touched the C'dale Super V4000

Post by Mark VandeKa » Fri, 17 Dec 1993 04:39:13

Quote:

>Although the coincident idler is a well-known fix in other domains, it
>hasn't generally been used in suspension bicycles.  I hazard that it
>is because of drivetrain efficiency.

Nice discussion of power losses due to chain flexing under tension (snipped).

Quote:
>There are some other considerations as well.  For example, the extra
>chain wrapping and unwrapping at the idler increases both friction and
>wear.  On the other hand, the idler can be made to "float"
>side-to-side so that the chain line is no worse than on other bikes,

Indeed, the idler on the V4000 "floats" and does not restrict the chain to a
single path.

(Snipped) More informed discussion of power losses and their real-world
significance.

Quote:
>Will the benefits outweight the costs?  Derailleur gears add weight
>and cut efficiency but are still worthwhile.  But nobody has ridden
>idler designs recently, so only time (and testing) will tell if an
>idler helps more than it hurts, or whether the loss in efficiency
>and increase in wear leaves the idea as just another good idea.

The benefit of the idler gear arrangement may be evident only in relation
to suspension arrangements that exhibit some significant amount of
bounce.  Suspension systems are, after all, designed to absorb and
dissipate energy.  It seems obvious that the power from one's legs that
moves the suspension up and down would not be moving the bike forward.  
The question is, "Is the energy lost to bounce greater than the energy
lost in flexing a (dirty) chain over an idler wheel?"  

As Don mentioned, there are other methods of reducing bounce.  The
simplest (I think it's the Fisher method mentioned in Don's post) is to
make the swingarm pivot around the bottom bracket.  If other problems
with this design (such as the difficulty of putting the bottom bracket
and pivot in such a confined area) are overcome,  it would seem to be a
more elegant and *efficient* solution than adding an idler.

As Mr. Shimano said in some interview I read a while ago (and I apologize
for memory based inaccuracy), "The difficulty in designing a bicycle is
that the engine is so weak."

Mark (No physics since 8th grade, but doesn't let that stop him) Vande Kamp

 
 
 

I've touched the C'dale Super V4000

Post by David Kepp » Sat, 18 Dec 1993 06:33:58

Quote:
>>>[Pong/Magic/Cannondale prototype bike.]
>>[Possible efficiency problems with idler in drivetrain.]
>[May still be an improvement over suspensions that bounce
> under pedaling load, but compared to those that don't...]

There are at least two ways to eliminate bouncing: first is to
"lock out" the suspension when pedaling, which also eliminates
the benefits of the suspension when pedaling, or, second, by
using a design where the chain length does not change as the
wheel moves up and down.  If the chain length changes with
vertical wheel motion, then chain tension, which tends to make
the chain "shorter", will cause suspension movement.

Pong/Magic/Cannondale uses an idler to force a fixed-length
chainline.  Fisher uses a four-bar linkage.  Harley-Davidson
motorcycles once used a vertically-mounted spring and slider.
The linkage and slider designs do suffer some tension-induced
bounce as the diameter of the front and rear cogs is changed,
but the forces are small compared both to conventional swingarm
designs that use a single pivot well above or well below the
chainline.  I believe also that the linkage and slider forces
are small compared to the bounce caused by your legs bouncing
up and down; and even the idler design won't get rid of that.

There is some weight penalty for using linkages and sliders,
and there can also be problems with bearing slop and slider
friction.  However, the efficiency penalty of using an idler
might put it at a disadvantage compared to a heavier but more
efficient design.  It will be interesting to see how well the
idler works in practice.

        ;-D on  ( With enough practice... )  Pardo

 
 
 

I've touched the C'dale Super V4000

Post by Naruhisa Takashi » Fri, 24 Dec 1993 23:36:19

Quote:

>You may be right, the $90 dollar figure I quoted was from the Outside
>article, not from Skooks Pong.  At $20 per, the ability to use one size
>of bearing for everything in the bike makes more sense.

I disagree. As I stated in my previous post, is doesn't make sense, to put
the some bearings you would put in the BB in the headset.  Not only is it not
economical (WHich I guess the buyer of this bike wouldn't care ...), but
it as unnecessary weight.  Why go through all the trouble of making light
weight cranks when you end up putting heavier than necessary bearings?

Naru Takashima

 
 
 

I've touched the C'dale Super V4000

Post by James W Gourgout » Sat, 25 Dec 1993 02:32:58

Quote:

>the some bearings you would put in the BB in the headset.  Not only is it not

        Speaking of the headset, I really question the Pong's design here,
unless they know a whole hell of a lot more about bearings than I do.
Just take a look at what would be the frame's "effective head tube
length".  It's about zero.  Therefore, whatever bearing/bearings are there
in the headset will take  A LOT of torque on them, due to braking forces.

        Now, given the size of the "universal" bearing that Pong intends
to use, it looks to me like only one of them can fit, maybe two, one right
on top of the other.

        I just can't see how this can be that strong, given the fact that
normal bikes have at LEAST 4 inches of headtube!

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Graduate School of Mechanical Engineering   --  -\<,    I couldn't decide
University of Pittsburgh / Pittsburgh, PA  -- ( )/( )   which bike to ride!"
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