How to make a carbon fiber bicycle ??

24 11 2014

Welcome to my newest endeavor.    The world’s first carbon composite framebuilding school!

Here you will learn the latest technique.  Utilizing some of the best materials available you will be able to produce a carbon fiber bicycle of excellent quality!  Not only that you can learn to do this in a small space with less tooling than you would think.

This will not be a 14 step Instructables on how to make a carbon fiber bicycle frame with electrical tape  and leftover materials from the local surf board shop.   Nor will it be a two day seminar on Gilligan’s island with the Professor making a bamboo bicycle lashed together with hemp twine.

Composite frames are built in many different ways but the two most prominent methods are the molded product and the T2T (tube to tube) product.  Both have advantages and disadvantages.  The prime advantage of the T2T method and subsequently the biggest disadvantage of molded is that tube to tube allows for customization of the size and tube shape/size for stiffness.  Molded products work well in volume but cannot be easily modified.  Certainly even a small change in size would require a brand new mold which is very expensive and beyond the ability of a small outfit or single craftsperson.

If profit was my only motive I would rather teach to a molded product.  It’s easier.   Lay up the stuff correctly on an expandable mandrel, place in mold and bake.  Bingo, bicycle!  T2T is constructed much in the same way as a steel bicycle but when it would come time to weld with the steel frame, instead we follow a strict layup schedule to build material on the outside of the tube joints, In a sense creating a lugged carbon frame.   In this case the bicycle frame itself is the tool/form, not a mold so it allows for a great amount of design freedom.   T2T can be better when it comes to creating the right ride quality.   The same properties that affect metal tube stiffness (size, shape and thickness) also affect composite tubes in the same way.  Only in the last couple of years have large bicycle companies even begun to modify their layups and designs from one sized frame to another.   This is something that is very easy to do with T2T.

Each frame is built with the best possible materials.   An Enve 2.0 fork is included with every build.   Tubing itself comes from Enve, Dedaccai, Reynolds etc.   You will learn general composite theory and procedures that you could use to build items other than a bicycle frame.   The education in that alone is worth the entry fee IMHO.   You will not waste innumerable hours and dollars on failed or dangerous experiments.  I have done that for you already.   Consider that you want to make a safe, reliable product.  I have tested these designs in house with a pneumatic testing device to far beyond the European standards.  You can rest assured that if you follow the course to the letter that your frame will last a very long time and be safe to ride.

Watching 100’s hours of YouTube videos and weeding through the chaff of the internet will not teach you as much as you can learn here.  Frames of the caliber you can build with your own two hands here cost as much as the course tuition, sometimes a lot more.

It is impossible for most people to conceive of creating a fully molded product in their own garage.   T2T requires less in the way of expensive tooling.  It is entirely conceivable that after taking this course you, the student could create more bicycle frames in your spare time, in a small workspace.

To facilitate this I will be offering build kits that include all the materials you will need to construct more frames.   One of the biggest hurdles to constructing composite frames is buying some of the necessary materials in such large quantities.  It is entirely possible to have to drop 3k on a single roll of bagging film when all you need is 2 sq./m.   This reality stops many before they can even start.

I can also paint your frames as well as provide groups/kits to complete your bicycle.  Special pricing is extended to those that attend.

Check out the website at

And contact me if you have any further questions.

All the best,

Dave Bohm

Bicycle framebuilding classes

15 09 2014

Frame Building School FAQ's

I don’t want you to hunt around too much.   Here is a list with links of all the available frame courses that I know about.   Please, check your options.   I am confident that I offer one of the best frame-building experiences going.

United States:

  1. United Bicycle Institute  (2 weeks) (cost $3000) (4 to 1 student ratio)
  2. Doug Fattic (1 week to 3 weeks) (cost 2-week 1800+material-3-week 2300+material/Material 4-500 average) (3 to 1 student ratio).  Painting course and Painting services available.  Student lodging available
  3. Yamaguchi (2 weeks) (cost $2700) (3 to 1 student ratio)
  4. David Bohm (Bohemian) (2 weeks to 4 weeks) (cost $2995.00) (2 to 1 student ratio). Painting services and student lodging available. Animals welcome.
  5. Hot tubes (1 week) (cost $2750) (1 to 1 student ratio).  Painting services available
  6. Ant bikes (1 week or 6 weeks) (cost $3150 1 week or $30,000 6 weeks) (1…

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You really don’t need a fancy jig…really!

9 05 2013

What I speak of a generally called a frame fixture or jig.   An apparatus that holds all the frame tubes in the right proximity to one another to allow one to weld/braze a bicycle frame.   Believe it or not a most excellent job can be done without one or with minimal fixturing.

Yes, I have one.   Actually I have three.   What does it do for the professional?  It makes us much faster while still being accurate.   Time is money and in addition to that I am fully capable of screwing up at a moments notice.  I have literally looked at a number and convinced myself it says something else so fixtures remove the possibility of making gross errors.   It is much easier to look at the seat angle of my Anvil fixture and when the hash mark lines up with 73 degrees, its 73 degrees.   Yes it’s a beautiful thing and I highly recommend the fixturing from any of the great suppliers.

I want to say this.  If a fixture is not easily set up and accurate when set up I rather not even have it.   Yes, I would rather build with a simple surface plate than have a fixture with a headache of a setup, is slow to setup and only opens me up to mistakes.   So it’s either a well made fixture, professional solution  or table.

Most students have the fixture/jig and numero uno priority when they get home.  I press very hard that so much comes before this.   Of course the basic hand tools, work bench, vise, torches but the next thing on my list is a flat surface of some sort.   You cannot (yes I said it) you cannot do good accurate work with only a frame jig.  You must have some way of confirming your work and therefore the surface plate is central to the whole process.   Does it have to be a big heavy thing?  not one bit.   We are not looking for aerospace tolerances here.  Many solutions will do.

Wait, there is more!   Do you know you can use your table as a fixturing device as well.   With some very simple hardware, much of it bought from tooling suppliers for very little money you can build accurately and quickly.  One of my former students just did such a thing and I am very proud of what he has done.   Pictures to follow.   The concept is simple.  It was relatively inexpensive and allows for great variations in design.  Also it allows for the requisite checks necessary to ensure a well aligned bicycle frame.

post3 Jig 3 Jig 2 post1


Disk brakes on classic road frames a big no, no….

27 11 2012

Certain items just don’t work with classic diameter steel very well.

A prime example of this is disk brakes for road, road race or cyclocross use.   I look forward to the day we have great hydraulic disk brakes for road bikes but in the mean time there are maybe more disadvantages than advantages.

Steel road fork design currently dates back at least 60 years and they were not engineered with disks in mind.   If you visualize a traditional caliper or cantilever brake you can see that the braking forces are equal on each side and that they are closest to the strongest portion of the fork (the crown)  Disk work differently.    The braking forces are on one side only.   The force is as far away from the crown as possible creating a large leverage ratio.  The forces are also typically pushing straight towards the rear of the frame as well.   In the worst scenarios this can cause the fork to twist permanently and essentially it is damaged beyond repair.

In order to alleviate this one would have to use fork blades that are much thicker and therefore heavier, stronger crowns and disk brake mounts.  This is next to impossible with traditional forks that have a brazed crown.   It is possible with unicrown steel forks but there is a weight penalty as well and it does not fit the aesthetic of a traditional lugged frame.   Even carbon forks optimized for disks tend to carry a fairly hefty weight increase for the needed strength, around 150 grams.  Many of these new carbon forks are of the newer taper standard and this requires a huge head tube on a steel frame which is once again heavy as hell (at least a 100grm penalty) and no lugs are made to fit them which means by default you are welding or fillet brazing a frame.

Now onto the disk brake.  The only one that currently works well for road/cyclocross  is the Avid BB7 and although admirable it has its issues.   Disk rub and squeal for one.  Weighs a lot itself, add in the beefed up fork and downtube and it weighs more.   They interfere with rack placement and fender attachment as well.   The only thing I think one could really claim as being superior is alleviated rim wear but good ceramic coated braking surfaces will last at least 3 years under the hardest of use and honestly don’t cost a lot more than a new disk so I consider it standard wear items.   Maybe someday we will have much better options but heavy, noisy, and mounting difficulties make them not the best choice in my book for Randonneur or cyclocross bicycles.

Now, you may ask, “Hey Dave,  I have seen students who had disk brakes on their builds at your shop.”  Yes, that is the case but you may also notice that the build method was different.   I will do this but typically the frame must be fillet brazed to take advantage of the tubing that can handle this sort of thing.  The frame will weigh more.  Usually I suggest using nice Paragon drop outs for the rear which incorporate a disk mount and they cost more and are more difficult by far to work with.

You may also say, “Hey Dave, my Google-fu shows me that lots of other builders have done just such a thing.”   Well,  I am open to many different concepts with framebuilding and many ideas are great ideas.   Although in my opinion most of these builders doing this are just plain wrong.   Many do not have the technical expertise to make a reasoned decision on this.    Second, most of these bicycles are city bikes and the like which really will not experience high loading factors over the units life, like a mountain bike or a road race/touring bike.  It is very different if you really plan to use it to a high degree.  This singular choice pretty much dictates the design and construction methodology of the entire frame/fork so please keep these issues in mind when deciding to use a disk or a traditional brake.

Trust your builder!

13 10 2012

This will serve as one of my eventual list of canned responses.   I get a lot of various types of e-mails.

This one is a classic.   The “I hired another framebuilder and I am doing research into how, when, where, why for them.”

Examples of this are everything from where did you get your tubing to what are your exact design specs.   Most of the questions border on flat out asking for proprietary design elements but really what is the more annoying thing is this.

You (the client who is contacting someone other than their primary builder) has hired a professional to service you and that you should let them do it.   Either this comes from two places.

First and probably least likely is that the framebuilder really doesn’t know where to get said product or how to design/build the product and that alone should be a warning to the perspective client.

More likely though is that the client is not allowing the framebuilder to actually do their job and that is provide the contracted services to the client.   Maybe its that the client is trying to run over the framebuilder? or maybe the framebuilder is trying to put off the client and the client isn’t getting the point?  Could it be the client is trying to have made a product that is out of the scope of the builder or more likely trying to get a less experienced builder to make something that is made by the specialists for much more?   One can only guess.

Dear Client of another framebuilder.   Trust your framebuilder!  You have paid them for a service, let them provide that service.   If they cannot provide that service then seek out someone that can.   If you are just being anal, backoff.    At the very least have your framebuilder contact me directly.  I will be much more open to answering professional peer questions than I am a random persons e-mail.

Oh and by the way.  Inevitably these e-mails are practically a demand for information.  A couple of “pleases and thank-you’s” would go a long way.

Takin’ it to a whole nother level…..

2 08 2012

Got to toot my own horn here for a moment.  I recently finished a paint job on a student frame from a few months back.   This student stayed for a month and built two frames taking both the 101 and 202 courses back to back.  This is his second frame and incorporates more advanced techniques like lug cutting and producing your own lugs through a process called bi-lamination.  He did almost all of this himself.  The lug decorations were 100% him.  I only guided on the next steps following the production of the first frame.

I am throwing down the gauntlet on this one.

the gauntlet

If you are looking for a bicycle frame building school and you can find one that has empowered students to produced  results  ANYTHING like this then I wholeheartedly suggest you go there.

Around here at Bohemian….who know, we take it to a whole nother level…..

Some Lug hotness on a Tuesday

4 10 2011

Lest you think that because I am totally lame and almost never update my stuff (blog, facebook or websites) here are some goodies I have been working on.

and a sneak preview of retardedniculousness coming out the shop…


You have got to train and train some more

1 09 2011

I think most people would take it as a given that you have to physically train to be an athlete.  One cannot get physically fit once in their lives and then hope to perform for future events without consistent training.   Another aspect we all take for granted is that one has to work on building new skills or working on the stuff that does not come naturally to them.   If a basketball player has amazing skills with layups but cannot free-throw well it makes sense that you would practice a lot more on the weak part of your game and not the strong one.

The very same is true of craft.  In this case framebuilding.    It takes practice and consistent training to grow as a craftsmen.   It is not enough to be very good at part of it and ignore your weak points.   One should study then practice new skills that will make one a better crafts-person.

Sadly though I see this very problem all too often within the framebuilding community and it is also perpetuated by the consumer themselves.

Everyone starts as a beginner, that is to be expected.   Then there is the period of learning.   You soak up everything you can read and practice.   Your muscle memory begins to develop and your work gets better by leaps and bounds.   A lot like bike racing where an athlete with talent moves up the ranks quickly and then seems to  peter  out when the going gets really tough the same thing happens to crafts-people.    I am not sure why.  Either they are not capable of more, or they feel that is good enough.    These are the types who would often say ” I have been doing it this way for X years and it is good enough for me”.   They don’t practice anymore, they don’t look for new and better solutions, they don’t seek out new skills to add to their existing repertoire.

Customers are also guilty of this.   I know it may come as a shock to some but I do not know how to do everything, I am constantly learning.   Painting  is good example of this for me.   I started the process of learning how to paint around 2006.   Many of my customers expected that two weeks of private instruction would make me a master of bicycle frame painting.   Five years later I am just to the point where I feel confident that I can tackle most anything you throw at me and even though I would be confident I could do it, I still know I have a long way to go.   I train with my painting.   By that I mean I paint more than bicycle frames that come in for service or my own work.   In order to be a good painter you have to…wait for it….PAINT!   I paint everything I can get my hands on.   My motorcycle, my car, the mailbox etc.  On weekends I practice airbrushing or mix a new color or make a panel.   How would I know what could be done unless I try it?  How will I be able to offer my customers something really neat unless I have experimented with it in the past.

So, what I am getting at here is that the time involved with building a bicycle or for that matter a guitar, chair or wonkywonderburple from Dr. Suess is not just the time you use to make it, its the time that you trained to get there.  It’s the time that you practiced and learned and read and failed.    A concert given by a violinist is not one hour at the music hall that you paid for but the thousands, maybe 10’s of thousands of hours that went into that one hour.    A great bike frame is not 300 dollars in raw materials and 16 hours like some think it is.   To me it’s the culmination of all the years that went before, all the knowledge and all the hours, dollars and setbacks. Only after all that effort,consistent training and practice will you be able to make something really great.

Alloneword…Cycling Caps

4 07 2011

Hey, you know every once in a while you come across something so good you just have to tell people about it.

One of those this is Cycling Caps made by Mary at Alloneword.

The caps are great!  Super easy to deal with and comon!  personalized envelopes?  over the top but it won’t probably come as some surprise I think this…..SUPPORT your  local or semi-local crafts-persons!!

Gorgeous student made bicycle!

2 06 2011

I just got some pictures of a student bicycle that was built here earlier in the year.  He got it built up and sent me some pictures.  Wonderful work and shows what someone can do with a little help and some determination.   The finish is electroless nickel plate and I am very proud of his finish work.  Clean brazing and great lug filing/edging.

Let the pictures speak for themselves….