Über ßike #4

25 08 2009

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:


whole head tube finished

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


Über ßike part 3

7 08 2009

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

Über ßike part 2

5 08 2009

Hi Everyone,

Made some progress.   Seatpost is done, Stem is done,  Frame is all mocked up.  You would think that from the pictures the end is right around the corner, but the truth is I am probably about 1/3 to 1/2 way there.   The prep is where its at.  If you do all your prep correctly, the brazing/aligning should go pretty easily and takes a short time.   After that there is the finishing and the paint work, which on this bike will be extensive.   Paint can represent nearly as much work time wise as the frame itself.  In fact some of the newer carbon frames have far more time in them concerning painting than it took to manufacture the frame itself.

The tubing is working out well.  It is strong stuff and hard to work with.  I have been weighing everything along the way and I am not going to break 3lbs for the frame.  I wanted to bust 3 lbs but metal has this small density problem and getting any lighter than that just isn’t in the cards.   What the seperate components weigh is interesting.  The tubes don’t weigh all that much more than carbon tubes.   Where the biggest difference is the hard points.  The head-tube weighs a lot, so does the BB.  You see some bikes where all the hard points are metal and the tubes are carbon but more weight savings could be had if you wanted to make a hybrid material bicycle by having metal tubes and carbon hard parts and lugs.

The other issue, is everything is big.   The head tube is 1.5” to look modern, the tubing is large diameter.   For instance a standard sized head tube would be lighter only because there is less metal there.  Physics is physics.  Bigger diameter, more metal, even if it is thin.

The other thing I thought I would talk about is polishing stainless steel.  Um, the short of it.  It is a time toilet.  Very time consuming.  So far the entire project is borderlining on 100hrs of labor so far.   The stem is going to be about 16 for instance.   There is no shortcut for doing a quality job polishing metal.   Every flaw has to be removed otherwise you will see the result in the final finish.   With traditional chrome you can plate copper and polish, more copper and polish.   Copper polishes easily because it is so soft, but with Stainless steel you are looking at the raw finish and there is no way to cover flaws so it has to be near perfect.   I do have some cool tools but this process basically comes down to lots of file work, then 80-120-220-320-500-800 grit papers, then buff.   Every square millimeter must be gone over 6-7 times.

As always you can check out my flickr account for more pics.


The price is what?

4 08 2009

What is maybe the second most popular question I get?  “How much does it cost?”   I thought that I would right a little ditty about it and I can refer this question to people instead of crafting it each and every time.

You tell me!   Really, I tend to work within the budgetary constraints of the client.   Custom bicycles are not only custom because framebuilders make them to size or for a particular purpose or a color but also to meet a price point dictated by the customer.  People are individuals and their ability to pay or needs wants can be very, very different.  If all you want is a purpose built MTB then I can help you.   If you want a masterpiece then I can help you.

Frames cost what they cost for all the standard reasons.   Materials, overhead and experience.   Nobody in this business charges drastically different amounts for bicycles that take similar amounts of time to produce and have similar material costs.  So shopping by price without any other consideration is comparing apples to oranges.

Yes, there are a few builders out there that charge exorbitantly low prices.  Usually newcomers who feel that they have to offer a low price to entice you the consumer to look past the fact they may have made ten frames and are still experimenting on you.  Overall though, prices are fairly common.  In fact, I saw a two framebuilders this week that have 3 years or less in this biz who are charging more than I am.  Guess a price adjustment is in order.

You should compare apples to apples in this business.  A well made but TIG welded, powder coated frame may cost 1100-1500.   It also takes 8 hours.   I just finished a fully polished lugged stem that took 16 hours.   Does the stem cost as much as the entire bike frame?  No.  But it cannot cost 250 dollars and still net any sort of profit for me.  That is why you may ask “why don’t we see X, it would be so cool!”  X usually takes too much time and is not commercially viable.   That is the cool thing about a custom framebuilder; we don’t work within the norm.  You want it we provide it and that is the beauty of this whole thing.

So, I would say I represent a great value for what I give the customer vs. the price.  I am always striving to exceed your expectations.  I guarantee that when you open that box with a spiffy new frame or bicycle in it your mouth is going to drop.

What does it cost?   I really can’t tell you until I know what it is we are going to make together.

Real framebuilders or not

2 08 2009

Paul Sadoff of Rock Lobster bicycles has a funny blog named “can’t we just get along”

Cant we just get along

The stuff is hilarious from the POV of a framebuilder.   I am sure other small business people would find it interesting too because business is business and we all face the same kind of trials and tribulations in a day.

A theme though that I find runs through it is a need to justify that Paul is in fact an actual framebuilder and not some sort of “poser”  Let me say here.  Paul is in fact a framebuilder.   He has been for many years and will continue to be so as long as he wishes to be.   I will say, there are many different business models in this business and non of them necessarily represent “real” framebuilders or not.   Yes, there are a few instances nowadays where a bicycle company is pure smoke and mirrors.   A vision of a bike company developed by a person better suited to marketing and web page development than actually building bicycles.

Mostly though, builders are plugging away trying to feel out their niche in this world.   Paul stated that he made 20 frames this month.    I make about 20 frames a year plus whatever else I can get my hands on.   We are just different.   Paul’s bikes are users.   Singular purposed frames made quickly and efficiently and don’t cost a lot.  Mine are well, generally time intensive and represent a vision of the “perfect bike” for the customer.   In the time it takes to make one of these I could make about 10 straightforward TIG welded bicycles.   I venture to guess though that Paul’s and my net bottom line in a fiscal year is about the same.   You can only work so much, there are only so many hours.   We both fill them up and spend 40-50-60 hours a week.   We both sell parts, and other stuff.   I think we both get to the same place, just down another path.   So I wish to Paul, who seems to be a bit pissed off all the best and yes, he is a real framebuilder and no, everyone who doesn’t produce a lot is not a “real framebuilder”