Uber bike technical details

24 10 2009

I  have had quite a few people ask what is  beneath all that spit n’ polish so I thought I would write a blog entry.

First the material.   The main tubes are produced by a company named KVA

It is a martensitic stainless steel with very high strength and ductility.   It is corrosion resistant and strong.   Because of this strength we can draw it into thinner walled tubing and thus save weight.    For this project this tubing was .4mm straight gauge (that is twenty thousands of a inch).   That is no butting was applied.

But you say “that is crazy thin, how do you weld it”.   Well you don’t.  It would be immensely difficult to TIG weld it.   This is where old techniques become high tech again.  Introducing the lug.

A lug is a slip fitting not unlike a plumbing joint that reinforces a joint and allows for brazing material have lots of surface area for joining.   This method is so good in fact that a majority of high end carbon bikes are made in exactly the same way.   A carbon lug and a carbon tube are bonded together using an epoxy.   Carbon/glue or stainless/silver.    Same thing.

Because the tubing was so thin these lugs were designed not only to look decorative but to act as the actual butting, or thickening of the tube to compensate for welding and stresses.   You can see that there are no sharp points to create a stress riser and the lug is longer on the sides and underneath where most of the stress is concentrated.   These are probably the thinnest lugs ever created.  A total weight for the TT/DT/ST/BB lugs was 74 grams.

These tubes were then joined using an old school technique that once again was the best technique for working with such light and thin materials.   Framebuilders call it a Bi-lam.  That is where one tube is reinforced and then fillet brazed to another tube.   This allows for custom geometry and a nice smooth, strong joint with few stress risers   Remember that working with such thin material that TIG welding is out, can’t be done.

So first the sleeve is brazed to the tube like this:

Then that is silver fillet brazed to the head tube like this:

And finally after cleaning it up:

I tried to incorporate all the newer stuff into this frame.  It is very compact and includes an semi integrated seat post with an seat binder of my own invention.  It works so well and is so easy I wonder why I did not think of it sooner.   It also weighs 4.6grm so take that lightweight crappy seat collars.

The rear end of the bike is S3 from True Temper.   Total frame weight is about 3.15 lbs in a 57cm.

Now, on to the Bling.   Parts of the frame are raw and consist of bead blasting and polishing.    The paint was hand made by me in a mortar and pestle and is the same copper silicate that the Egyptians used.  It is also made a bit darker on either end with the addition of Lapis Azule from Afghanistan.

The lugs are inlaid with Paua Ablalone.   The head badge is pure silver, hand made with inlays of gold mother of pearl and Paua as is the seat post which is also 953 stainless steel.

The final touch is rare metal leafing.   The fillets are made of silver and would tarnish.   To prevent this I leafed the fillets in pure Palladium leaf.  The faux fork crown and bottom bracket are all palladium.  The sides of the lugs also have 24kt gold accents.

Then of course my signature in 24kt gold leaf

Mix together thoroughly, bake at 350 for 300 man hours add your toppings of choice….

My thanks on this project to Fairwheel bicycles for helping with some go fast goodies.    The wheels, shifters, brakes and cranks.   Selle Logica for the custom molded carbon saddle.  I also would like to thank EE cycle works for the brakes and crankset.

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