[CR]need detailed drawing of demultiplicator

(Example: Framebuilding:Brazing Technique)

From: "Howard Darr" <hdarr@localnet.com>
To: <classicrendezvous@bikelist.org>
References: <99C49155-BC57-4B0A-92BC-8D2B0FB0F099@earthlink.net>
Date: Sat, 4 Aug 2007 15:17:41 -0400
reply-type=response
Subject: [CR]need detailed drawing of demultiplicator

Greetings,

I would like to fabricate one. Does anyone have a link or picture of one?

Howard Darr
Clymer PA USA


----- Original Message -----
From: Richard Risemberg
To: classicrendezvous@bikelist.org
Sent: Saturday, August 04, 2007 11:44 AM
Subject: [CR]More on ceramic bearings (long quote)



> This from ZIPP, who makes (very expensive) ceramic bearing
> wheelsets. Very interesting, and little of the blatant sales pitch
> in it.
>
>> The use of ceramic bearing systems in cycling is starting to
>> accelerate since the introduction of own ZIPP Z3 wheel set two
>> years ago and now with the adoption ceramic bearings by Campagnolo
>> I believe we will see an inevitable increase in the use of this
>> technology. Judging from the notes and phone calls I receive, there
>> is quite a lot of both excitement and confusion out there so this
>> is a great opportunity. I will try to answer all your questions,
>> but please excuse me if I tend to go on too long: I love this stuff
>> and I tend to get carried away.
>
>> I believe it was the writer Robert Heinlein who said something
>> along the lines of: "Any technology sufficiently advanced is
>> indistinguishable from magic." Ceramic bearing systems aren't quite
>> magic, but the technology behind them seems to be getting closer
>> all the time.
>
>> I am going to talk about ceramic bearings, bearings in general and
>> ZIPP bearings in particular as these are the bearings I am most
>> familiar with. Other manufacturers such as Campagnolo will have
>> faced similar challenges in adopting ceramic technology and will
>> have addressed them in ways best suited their own needs.
>
>> When speaking of ceramic bearings, we are really speaking of
>> ceramic balls replacing the more common steel balls in the bearing
>> assembly or system. Ceramic bearings do offer dramatic potential
>> for significant performance advantages, but the key word is
>> potential. Optimal performance is a result of an entire bearing
>> system rather than as a result of the ceramic balls themselves.
>> What the ceramic balls do by their physical properties is raise the
>> bar of what is possible to achieve in the entire system.
>
>> When you start talking about any material, you have to remember
>> that there are steel battleships, bridges, "tin" cans and my
>> favorite toy, the slinky, all made of steel. In other words, each
>> material has a range of properties and it's not the magic material,
>> it's what you do with it and how you apply the material properties
>> to a particular design solution.
>
>> Modern bearings, any bearing ceramic or otherwise, are really
>> pretty amazing technological objects. Steel ball bearings used in
>> cycling have tolerances now measured in millionths of an inch. In
>> top quality hubs, steel bearings typically will have a tolerance of
>> between 50 and 60 millionths of an inch between the balls of a 12
>> or 15 ball set. This is not easy to do, but by pushing the
>> manufacturing envelope further (and spending a lot time and
>> effort), steel ball bearings can achieve a precision of 10
>> millionths of an inch total variance per matched set of 15 balls.
>> Of course to take advantage of this precision in the ball
>> manufacturing, the other parts of the complete assembly must also
>> receive similar attention. This attention to detail results in
>> improved performance across a broad range of parameters, but the
>> basic material properties become the limiting factor. Being the
>> performance fanatics (and that's a nice way of saying technology
>> geeks) we are here at ZIPP, all our hubs using steel balls are
>> using ZIPP designed and custom manufactured bearings sets that
>> achieve less than 10 millionths of an inch total variance in
>> roundness and size in a matched set. A similar attention of detail
>> is applied to the remaining parts of the bearing assembly.
>
>> Now in talking about the above it's time to mention a key part of
>> manufacturing: The more time, effort, and precision you insist on,
>> the greater the cost. It's pretty much a rule you cannot get
>> around. The cost, by the way, increases at an ever accelerating
>> rate with each level of precision achieved. By adopting new
>> technology and materials (Ceramics!) new options become available.
>> Dramatically greater precision and performance can be achieved and,
>> of course, the cost also accelerates along its ever increasing
>> path. That's the answer to why the price differential exists
>> between ceramic and steel bearings.
>
>> Ceramics have been around for several years, but it is the new and
>> rapidly developing new manufacturing technology that allows the
>> dramatic increases in precision that were unthinkable until
>> recently. They are used in numerous industrial, military and
>> aerospace applications where long life, high speed, heat, pressure
>> and low rolling resistance are required. As with anything, a range
>> of quality is possible...but it is the manufacturing technology at
>> the highest level that breaking new ground and offering
>> unprecedented performance potential.
>
>> How much benefit is possible from adopting this new technology?
>> According to reports from real world testing done by ZIPP sponsored
>> Team CSC an average reduction in wattage of three to four percent
>> under our standard bearing systems, already the tightest standard
>> within the industry can be expected. For an average trained cyclist
>> developing 250 watts, that's a savings of approximately 10 watts.
>> At any level of competition, that is significant. The key is every
>> part of the bearing system has seen marked improvements in
>> precision resulting an a total benefit greater than the sum of its
>> parts. Similar to current math theory, at some point numbers reach
>> a point where the rules just don't hold true any more.
>
>> Anecdotally, one our ZIPP representatives recently became a world
>> record holder on the track. After numerous attempts and misses at
>> the record by a few hundredths of a second, he broke the record
>> after switching to the ceramic bearings. He has since lowered that
>> record again using the same set up, but in several tries without
>> the ceramic bearings has been unable to ever match his original
>> record breaking attempt. Of course this was not a scientific test,
>> but try to tell him the bearings don't make a difference! Matched
>> sets of ceramic balls used in ZIPP bearings exhibit tolerances of
>> LESS then one-millionth of an inch total variance in both size and
>> roundness with a corresponding increase in surface smoothness. This
>> is near the technological limit of measurement and worlds better
>> than any steel bearing of any rating or type. These bearings are
>> currently exclusive to ZIPP and NASA.
>
>> Ceramic balls of the highest quality are made of pure silicon
>> nitride. (Earlier ceramic bearings of any type, possibly familiar
>> to skaters or skateboarders, were often merely coated steel balls
>> inserted into standard non-specific races and offer no comparison
>> to the current state of technology.) The critical issues of
>> manufacture are purity of materials, chemistry and particle size
>> control, ability of the pre-manufactured material to flow easily,
>> packing density, uniform compaction, micro-structural development,
>> geometry, surface quality and finish.
>
>> As mentioned earlier, ceramic silicon nitride balls exhibit much
>> greater hardness than steel balls resulting in at least 10 times
>> greater ball life due to the ability to hold the surface finish
>> longer. (Later I will mention cryogenic treatment of the steel
>> races. This is required to take advantage of this durability and
>> prevent the hardness of the ceramic ball from destroying the race.)
>> The ball has dramatically smoother surface properties than the best
>> steel ball resulting in less friction between the balls and bearing
>> race surfaces. Thermal properties are also dramatically improved
>> over steel balls resulting in less heat build up at high speeds. To
>> achieve the final surface finish, the balls are floated on a
>> magnetic field and polished with plasma stream. They are rated to a
>> spin rate of 300,000 rpm versus a spin rate of 33,000 for our steel
>> balls.
>
>> All the other parts of the bearing system and of hub design are
>> directed at optimizing the potential of our bearing technology,
>> both ceramic and steel.
>
>> The custom steel bearing races are designed and manufactured
>> specifically for the loads and requirements of a cycling
>> application. The races are cryogenically treated at minus 300
>> degrees Fahrenheit to harden and align the crystalline structure of
>> the material. The races are then polished to a surface smoothness
>> 30-percent greater than an Abec 9 rating, the highest international
>> standard rating level. Each bearing assembly also includes a thermo-
>> plastic based waffle shaped seal that encloses and locates each
>> ball to its optimal location in the race. Friction is further
>> reduced by this system as individual balls are kept at their
>> optimal location at all times. Lubrication is provided via a
>> depleted barium hydro-flex lubricant ($650 per kilogram and used in
>> all
>> ZIPP bearings!) that is also a product of the space program. The
>> lubricant is actively hydro-phobic, meaning it repels water at a
>> molecular level. The lubricant is also thermally stable and
>> exhibits the same properties at -200 degrees as it does at over
>> 2000. Most importantly, it exhibits the lowest friction coefficient
>> of any lubricant available. Designed to match the bearing
>> performance with modifications adapted to current use, the
>> lubricant is rated to spin rates of 300,000 rpm and an expected
>> life equal to that of the bearing.
>>
>> As a final word, properly designed ceramic bearing systems do in
>> our opinion increase performance and will become more common,
>> perhaps the future standard. Certainly at the top levels of the
>> sport the difference is significant enough to change the out come
>> of races all things being equal among similarly gifted athletes.
>> For the time being, however, the cost of such technology, even the
>> availability of the materials themselves remains a barrier to wide
>> application of such systems. Manufacturers like ZIPP and now
>> Campagnolo (others to follow) will continue to push this direction,
>> but ultimately, it is the individual rider who has to decide if the
>> current state of the art is of value to them. In the auto racing
>> industry there is an old saying: "Speed costs money; how fast do
>> you want to go?"
>> Bill Vance
>> National Sales Manager and Factory Guy
>> ZIPP Speed Weaponry
>
> http://www.velonews.com/tech/report/articles/5327.0.html (Near middle
> of page)
> --
> Richard Risemberg
> http://www.bicyclefixation.com
> http://www.newcolonist.com
> http://www.rickrise.com