A few weeks back I had Sky and Anthony come visit the shop after a mini-tour around the southwest and a side trip to our local bike swap.  Have a look see on the velocult website and check out what these guys do.  It is very cool.   Anthony proclaimed Chelsea to be the coolest dog ever!  I agree.

Check out velocult at:

Velocult blog visit of Bohemian Shop

Velocult website

Finally got up a website for my newest endeavour,  Framebuilding classes.   To kick it off right I made my first piece of schwag for the occasion.

go to framebuilding school!

How I got the URL?  I will never know

Except a lot of those choppers suck  and Eriks bikes don’t. Erik recently posted a video explaining who he is and what he is about.   I sometimes wish I could be this candid.   Here it is in all it’s funny assed glory!  This is not appropriate for the office!

So, here is why I think Erik is cool.   First he has heart and does what he wants.   Erik has some real creativity and originality.   Something that is sorely lacking in our business.   In fact many builders hunt through the data book and copy something straight out of 1940.   Well that is all well and good if you are…..actually from 1940 but if you are 23 years old I have no idea in hell why you would do such a thing.

Erik explores themes that others don’t.   Bikes are meant to be fun.   We,  that includes myself take ourselves entirely too seriously.   The car guys have fun:

O.k.  I admit that is ugly as hell but at least they were thinking outside the box.   Motorcycles same thing….

Except I really like this one.   Getting back to Erik for a moment.  It is refreshing  in a sea of frames made with 4 lugsets and painted the latest earthtone (which right now is a daring brown) to see something really custom and out there.

Love it or hate it but you can’t deny he is an original.

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.

Well she is done.    It was shown at Interbike.  I took some pictures and hopefully soon she will be ridden by her new owner.   This frame needs some explanation but I will reserve that for the end as not to bore you.

Now for a bit of explanation.

The frame is predominately made of KVA stainless steel tubing.  Akin to Reynolds 953, but made domestically and of a special draw for this bicycle.   Total bicycle weight is 14lbs complete.

The lugs are custom made from stainless steel as is the bottom bracket and most all the fittings.   The inlays are mother of pearl and Paua abalone.  The welded area which are actually silver brazed are covered in Palladium leaf along with some accents in 24kt gold.   The headbadge is pure silver with inlays of abalone and mother of pearl.    The paint is a natural pigment of lapis azule that was ground specifically for this project.  All the raw sections you see are bead blasted or polished stainless.  Overall it represents about 300 hours of work.

Hope you like it.

Dave

Yes, the offending decal.   That awful piece of plastic adornment that bicycle manufacturers heap on us.   Not once, not twice but 20 or 30 times on a single bicycle.

Are there many other consumer goods that assault us in this manner?  I always have this vision that the world will end when I see this rolling down the road.

Nobody in their right mind would be seen rolling in a supercar with the name plastered across it in all directions but men and women of generally good taste turn into the worst offenders of design when they zip up their gaudy walking billboards of advertising and mount a bicycle that would look right at home at the latest Nascar event.

Kind of like this:

Most of us don’t race right?   If we do, do we race for the actual company that makes our bicycle? then why the heck should we be advertising for them?  Why should we be throw away good, clean design for massive volumes of crappy block lettering.

Exhibit A:

I don’t even know who this Avanti company is.  Found it on the net but what do they think will happen one day?  That Alzheimer’s will set in overnight and I will have possibly forgotten I ride an Avanti and have to be reminded 13 times?  Will my clubmates forget that I ride an Avanti Quantum?  Will they say.   Jeez, I couldn’t tell this is an Avanti Quantum, if he just had it written on his seatstays I would buy that bike.   Who the heck in this day in age doesn’t know you can type Avanti bikes in a search engine and find it.   Nope they got to tell you it’s www.avantibikes.com

Please lets stop the indecency of the ugly bicycle.   Rules of thumb.   If you would not be caught driving in it.  If you would not wear it.  If you would not buy or hang it on the walls of your home and you would not even wish it on your worst enemy then DON’T RIDE IT!

I got a call recently.  A very nice fellow who wanted a bike frame.   All was going fabulously.  I always bring up the “how long it will take” question.

Silence on the other end…..You still there?

Yes, this is the biggest deal breaker of them all.  The dreaded backlog.   For a framebuilder a backlog is a good thing.  That means every morning I wake up, I know that I have work ahead of me and a eventual check to pay dem bills.

So oddly,   I find that the standard time that a client thinks they will have to wait is about 6 weeks, maybe three months tops.  Where this comes from, I don’t know.  Maybe it just seems like a good amount of time to get something like a bicycle completed but lets look a little further.

The fact is,  I had stuff to do before that call and thank God for that.   The backlog is fluid.  It grows to a point that most people are unwilling to wait anymore, it dips then climbs again.   Some builders can command a much longer backlog than others, some as much as 7 years.  Other builders manufacture quick to build product.  If you build a frame-a-day you can deliver quickly but then again this is usually lower priced product with less profit margin (not always) and one is riding the raged edge if business falls off for some reason.

The ol’ six weeks is a standard joke in the frame world.  We know customers want to hear six weeks and so some builders will tell them what they want to hear.  Once you have the money, what can they do?  6 weeks often becomes 6 months.

I can only speak for myself though and I don’t build quickly.  Between frames, paint work, teaching and side jobs I only produce about 10-12 very nice bike frames a year.  12 people means a years backlog.  Add a few complicated bikes, maybe a tandem and some fancy paint jobs and some design work on the side and that turns into 18 months.

If I ever get to the point that I can deliver from call to door in six weeks or less.  I think I might hang this gig up.

Sorry about not posting more. It has been a grind to the finish. Most of the time when I get near the end I just put my head down and try and finish. No time for pictures and the like. Uber is basically done. Just some finishing left to do and then painting which will be quite intensive.

It is not like those videos you might have seen on You tube where Colnago bangs out 100 frames a day with all the precut stencils and 8 spray guns with every color available. It is tedious work. Enjoyable but many, many hours are spent masking, sanding, spraying and sanding some more.

The frame weighs what it weighs. Steel is not ever going to win the weight war anymore. But it is nice and light and for the entire package of frame, fork, stem, and seat post it weighs 2130 grams or 4.7 lbs. I just got the wheels from Jason at fairwheel today (thank you Jason) and they weigh with tires about 1600 grams or 3.5 lbs so I have about 5ish pounds or so for the rest of it to reach my target weight of 13.5 lbs.

Also apologize about the cruddy photos. My little point and shoot is always the greatest.

I will see you all after I crawl out of my paint booth cave in about a week and a half:)

Dave

Still working on Uber bike…..Had to get some “real” work out of the way. You know the kind that pays you. Show bikes are awesome but represent a huge undertaking that doesn’t pay you right now and das bills have to be paid.

So where am I. I am finally brazing this frame together. The front of the front end is brazed and I am going to do the finishing down to the last bit with it partially finished. Then I will joint this in one operation to the seat tube-BB- and chainstays. Why? mostly because it is just easier to work with a smaller piece. A full frame is always banging into everything and is cumbersome, especially because I have some real detail work to do.

So the first thing is that I have to braze all the sleeves to the tube and then braze/weld the tube together. We generally call this a Bi-lamminate. This idea dates way back to the early bicycles in England and France. That is you have a sleeve to add structural reinforcement and then you fillet braze that to either the head tube or visa versa. First I did the seat tube and then the other eight sleeves.

This is the same piece cleaned up

Seat stays:

Then I made up the head badge.

made up some inlay for it:

Brazed head badge and head tube rings…..

Polished the seatpost. Most of this is good ol scrubbin’ mostly done in front of the TV at night.

Then I brazed the top tube to the head tube. A little info about this. This is stainless steel and it is quite sensitive to filler metals and heat. Stainless absorbs heat a lot faster than some other materials and if too much is used serious distortion of various things can occur. Silver not only bonds well but reduces distortion to nearly zero because of the low heat needed to melt it. You don’t often see this technique used. This is high content silver rod specifically made for this purpose (Fillet pro silver rod) and it can be a lot more expensive than brass or “nickel silver” which is a mix of brass and nickel and has no silver.

Silver requires a completely different technique. It’s melting range is super narrow compared to bronze and therefore does not build the same. Torch control is paramount. The upside. A super strong joint. Upwards of twice the strength of bronze and 50% more than nickel silver without distortion and a very low heat input which retains more of the original properties of the material.

Just brazed:

flux cleaned off:

finished

whole head tube finished

Now I am going to completely finish this, then join it all together. More to come….

O.k.  got a little sidetracked.   Finished mocking up rear triangle.   Each piece started as thick stainless tubing and was bored to size, thinned substantially, mitered and fit up.

First the raw stainless tubing

Then machine to fit on my 1943 southbend lathe which came off a WW2 submarine.  Still wonderfully accurate after 66 years.

Then miter the chainstay ports to fit BB.  Just to give an idea.  A standard frame would have 10 miters.  This frame has 20 mitered tubes.  Essentially making a frame twice is what we call it.

Then same thing on seat stays.

final look

Throw in a little carbon fiber to the stew…..

Points from side.  I wanted these to line up.  I retain these points during the brazing.

So then I get it all mocked up and I discover something I did not quite think through.  Yes, we framebuilders are not perfect.   It may be one thing when you build the same thing over and over again.  You learn it perfectly.  You now how one change will affect something else.   In the case of mass produced frames.  They model every last scenario, then test.  That standard does not change.   Custom frames throw you a curve once in a while.

I wanted to build an extended seat mast bicycle frame.  I lowered the top tube, so far so good.   The rear triangle though is very small and this increases the angle of the seat stays as they attach to the rear of the seat tube.   In turn it decreases the clearance for a tire.  I did not fully consider this fact when I drew up the plans initially.   The tire would fit but only leave 1.5mm clearance on either side.   Not enough if one was to have an untrue wheel or a lumpy tire.   So what to do?  First, go have lunch…..solution…grind away interiors of seat stay.  Cap with leftover KVA headtube and voila 5mm of tire clearance.   Good custom framebuilding is often just finding good solutions to problems.

The carbon fiber previously will be cut down and a section added internally to the seat tube to help support the seat mast.   I designed the seat lug for this but it is paper thin steel tubing (.4mm) and I want this frame to last a LONG time so a little extra insurance here is great.   The same thing will be done to the downtube where it joins with the headtube to reinforce this high stress area.  Much the same idea as the exogrid stuff from Titus (well, without the grid)

Well, more to come! 

Dave Bohm
Bohemian Bicycles