Book review – Lugged Bicycle Frame Construction

2014-07-24 002 001

I have recently been considering getting some brazing equipment so that I could make repairs to frames that have minor failures, rather than sending out to a frame builder for this service.  Having taken UBI’s lugged frame building class a few years back, I had a general idea of what I might need, but didn’t want to go any further until I re-familiarized myself with the topic of brazing.

I found Marc-Andre Chimonas’ book, Lugged Bicycle Frame Construction, on the evil empire (Amazon) website, with what appeared to be some favorable and thoughtful reviews by actual readers.  When the book arrived, I immediately delved into it and have now read if not studied much of the book.

It is written with a dry, understated wit, with an emphasis on the science of frame building.  There are numerous zingers in the text, hidden amongst the tables and formulas.  Consequently, I thoroughly enjoyed reading it.  The author is a physician (which he describes as his “day job”), a writer (of both technical manuals and fiction), and a frame builder.

After reading just the first few chapters, I began to seriously question the idea that anyone can take a frame building class that lasts only two weeks, and from which an actual frame is produced.  Whether that frame is safe to ride may be another thing altogether.  My own frame has several flaws that can probably be corrected, but more on that later.

The book is logically organized and takes the reader through introductory concepts such as nomenclature, frame geometry, measurement and sizing protocols and includes helpful tables for determining angles and lengths for different sized riders.  He naturally recommends smaller wheels for smaller frames, and there is a good discussion of toe overlap and bottom bracket height.  He states his opinions about frame geometry as if they were facts, and that may irritate some readers, but I found it refreshing.  For instance, recommended BB height is 25 cm for pretty much all types of normal road riding.  This is a lot lower than you will find in production bikes.

Another interesting concept that I found both helpful and puzzling was the idea of controlling the variables in frame building.  He differentiates between “operator controlled” variables and “outcome” variables.  Outcome variables are the result of the frame builders operator controlled variables.  But, he describes outcome variables to include BB drop and toe overlap, which in my mind are operator controlled.  At any rate, what is clear is that frame design is a highly complex  undertaking, and one that is aided by software.  He recommends using excel and offers a link to a useful frame design spreadsheet, which is available on the author’s website.

There is a quick trigonometry and metallurgy review (which the author calls optional), and then the theory turns into fabrication as the author goes through chapters on frame parts, tools, mitering, torches, brazing technique, and lug modification.  Again, the author doesn’t hesitate to state his recommendations, even down to a specific brand or manufacturer of a particular tool.  For me, someone who didn’t take shop class in high school, the specific advice is extremely helpful.

After digesting many of the chapters, I decided to drag out the frame I completed 2 years ago but never finished filing or painting.

My frame with front-center at 59 cm - a little shorter than I wanted.

My frame with front-center at 59 cm – a little shorter than I wanted.

I built this frame for myself, designed around a 650b wheel size.  I wanted enough front-center distance to allow for fenders and decent sized tires.  The book uses a formula to determine an ideal length.  I plugged my numbers into his formula and found that I won’t have toe overlap with this frame, so that is a relief.  I did have to use a longer than usual (for me) top tube length to get this much front center distance (combined of course with all the other measurements).  That means I’ll use a short reach stem when I eventually build the bike up.

2014-07-24 001 006

One of the things that troubles me about my frame is that it was built so hastily and with so little actual knowledge.  Well, after reading the brazing chapter I think I have reason to be concerned.  I remember having a lot of trouble sanding enough material off the top of my fork blades, and off the inside of the fork crown so that the legs could be inserted without a lot of force.  After hours of filing, I still wasn’t happy, but ran out of time so just brazed the fork legs into the crown even though the fit was tight.  This is definitely a no-n0 – there needs to be enough room for the silver to flow into the joint.

Here are some other details of the frame I built.  Using this book as a resource, I will be able to correct the other two (known) mistakes on the frame.  I may decide, however to build a new fork.  And, I now know what kind of equipment to purchase and how to use it safely, so I am looking forward to being able to do my own small repairs.

2014-07-24 001 012

Nice looking BB

2014-07-24 001 009

Mistake on the seat stays – they are out of alignment

2014-07-24 001 007

Drive size DO not yet cleaned up and filed – you can see I got the tubes a bit hot.

2014-07-24 001 013

Aaack! Seriously out of whack shifter bosses – the jig probably got bumped when I turned away to get more silver.

Small wheeled bicycles: the solution for shorter riders

1980's ALAN with 24 inch wheels

1980’s ALAN with 24 inch wheels

One of my favorite Georgena Terry witticisms goes something like this:  “if we were all 3 inches tall, we would be riding bicycles with appropriately sized wheels.”  Why the cycling industry has shoved 700c down everyone’s throats has mainly to do with the racing fad we are all now recovering from, and little to do with what is the right sized wheel for a given rider and a given application.

Currently, the cycling industry is going through another fad: wheel and tire size crazes – 650b, 29er, and super fat, to name a few.

When frames are built, the wheel size and tire width must be determined in advance.  A small frame cannot properly contain a large diameter wheelset without serious comprises in the frame geometry.  Placement of the rear brake bridges and length of the fork blades determine how much clearance a frame will have with the wheel size it was built for.  By using long reach brakes, it is possible to convert a frame built for a larger wheel size to a smaller size.   But why is this even necessary in the first place?  Why aren’t bikes for smaller riders automatically built with appropriately sized wheels?

Well, partly this is because Americans have demanded the lowest price possible when it comes to purchasing just about anything.  To achieve this low price, bicycles must be manufactured anywhere but here, where our wages are astronomically high relative to manufacturing-based countries such as China and Taiwan.  We also have labor laws, environmental regulations, and lots of red tape which help to drive up the cost of manufactured goods relative to that of other countries.  While I am glad we protect our workers and the environment, consumers don’t seem to care and we quite happily purchase many of our goods from other countries where such laws do not exist.

These factors contribute to the “one size fits all” wheel diameter phenomenon.  In order to produce bicycles at a price point that the consumer demands, it is much less expensive to equip them all with the same wheel size, regardless of the frame size. The result on a smaller frame is that the head tube angle will be slackened to allow room for the front wheel to clear the downtube and help reduce toe overlap (all manufactured forks have the same rake – so there’s no extra cost there except to cut the steerer to different lengths).  And, on really small frames, there might not be much of a headtube at all, because the manufacturer has determined that the only thing a shorter rider cares about is standover height.  A super slack head tube of 69 degrees with the standard 45mm of fork rake is going to be a handling mess for a road or commuter bike.  The bike will have lots of wheel flop, so arriving at an intersection and slowing down will feel very unstable and it will be hard to keep the bike upright at slow speeds.  Instead, the smaller frame should be designed to accept smaller wheels, allowing for normal rake and trail to allow for good slow and high speed handling, and for an actual head tube which will help to improve the overall comfort of the frame.

Daniel Rebour 1962 catalog Rene Herse

Daniel Rebour 1962 catalog – Rene Herse

All riders should measure their bikes by top tube length, not seat tube length.  If you look at photos and drawings of cyclo-touring bikes from times past you will see that there is very little seatpost showing – these bikes are tall relative to the rider, at least by today’s standards.  And, they often used smaller wheel sizes, which would help to lower the saddle height relative to the ground. By riding a taller frame you can get the stem higher relative to your saddle, and these older bikes had lower bottom bracket heights, making it possible to put your toe down at an intersection, rather than dismounting.  Unfortunately, modern cycling “wisdom” tells everyone to have at least 1″ of clearance between your crotch and the top tube.  Why?  Well, apparently cyclists of the mostly young and male variety often somehow crash land on the top tube, causing serious and sometimes lasting injuries to their private parts.  However, if you are riding in a way that allows you to crash on the top tube, you are probably taking unnecessary risks.  And, it wouldn’t matter whether the top tube is 1 inch below your crotch or 3 inches below your crotch.  This kind of accident would require you to have lost control of the bike while still straddling it, such as attempting jumps and other tricks that our culture has decided is a good thing for young boys to try. A greater standover height can also be achieved by using a lower bottom bracket, so you could still have a tall frame and the “requisite 1 inch clearance” on the top tube if a lower bottom bracket were the norm.

However, worse and more prevalent injuries can be caused by riding bikes with too long top tubes.  Smaller riders often select bikes with short seat tubes only to be confronted with a super long top tube (this is another way the manufacturer crams a 700c wheel into a too small frame).  Riding a bike with a too long top tube can cause neck and lower back pain, arthritis and hip degeneration.  This kind of injury happens over time and can also be exacerbated by doing super long rides even on a bike that fits correctly.

1930's Peugeot Mixte 650b

1930’s Peugeot Mixte 650b

Some smaller riders prefer to ride mixte frames.  These frames are much stronger than typical “women’s frames” because they have a sloping top tube which extends all the way down to the rear dropouts.  This makes for 3 rear stays instead of two, and helps to offset the greater flex of the head tube away from the seat tube under acceleration.  This solves the problem of standover height, but unfortunately does NOT address the problem of having a too long top tube.  Why?  Because mixte frames were produced in smaller runs, there are limited choices as to the headlugs which provide for a predetermined sloping top tube angle, forcing the manufacturers of mixte frames to produce them with relatively long top tubes.  Peter Underwood has an interesting discussion of this topic here.  He also argues that these long top tube lengths on mixte frames were the result of builders wanting their mixtes to conform to their “norm” for top tube length – which was 21 inches (53.3 cm) for custom builders.  The 1930’s Peugeot pictured above has an effective top tube length of 56 cm!!  While this super long length is slightly offset by the upright bars, this is a bike that could only be comfortably ridden by a person at least 5’6″ tall.  The other mixte frames currently in my shop all have effective top tube lengths of 53 cm.  This is way too long for a small rider, generally speaking.  That is one reason I discourage small riders away from non custom mixte frames, unless they are mainly going to do casual riding in an upright position.

The solution is to design a bike frame in a logical way such that the frame dimensions are proportionate to the small riders’ anatomy.  This naturally includes using smaller wheels.  Such a frame can have a nice big head tube, and will be bigger overall, which will produce a much more comfortable frame and riding experience.

Terry Symmetry 51x51 with 26 inch wheels

Terry Symmetry 51×51 with 26 inch wheels

You can find such frames if you are diligent.  The bike shown above is my Terry which I purchased as a frame and fork.  It is not a custom frame but one I picked up on eBay which was a leftover NOS from the 90’s TIG welded with Tange tubing. It has great geometry with no compromises so it handles well in all conditions, and has absolutely no toe overlap.

Unfortunately, buying a new complete bike for a small rider will not be so easy.  There’s no point in trying to find such a bike at your LBS.  The best thing to do is order a bike from a well regarded shop such as Rivendell,  Georgena Terry, or your local custom builder.  These builders automatically design their smaller frames proportionally and with smaller wheel sizes such as 26 inch, 650c or 650b.  One thing I have learned is that I prefer riding frames with steep angles – 73 or 74 on the seat tube, and since I like a low trail bike I prefer a steep head tube angle combined with a lot of fork rake.  As far as I know, no one has researched whether steep angles are more comfortable for smaller riders, but I like the feel of having more of my body closer to the front of the bike.

The vintage line up in smaller frames works best if you can convert a small frame to 650c or 650b, or if you can find a small frame originally built with smaller wheels, such as the ALAN depicted at the top of this post, which was designed for 24 inch wheels.  Until more small riders begin demanding appropriately sized bicycles and wheels, nothing will change.  So, if you do stop in to your LBS, let them know that you could be a good customer if only their suppliers would provide the kind of bike which is safe and comfortable for you to ride.

 

Extreme Bike Makeover: 1980’s Guerciotti

rando conversion

I’ve been riding this 1980’s Guerciotti for several years now.  When I first purchased it, as a frame and fork, I converted it to 650c, and turned it in to a city commuter, as shown in the photo below:

When my Nitto city bars were recalled, and the promised replacement bar never arrived, I decided to convert it back to a regular road bike, emphasizing its slightly garish 1980’s color scheme:

1980's Guerciotti

I really enjoy riding this bike – it is fast and a great hill climber.  My theory about its superior performance is that its small diameter seat stays and the short wheelbase make it fly up hills.  I won’t say whether the bike “planes” as I am not convinced of this theory, although I do find it interesting.  Whatever the case, I can ride this bike over hill and dale and not tire out the way I do on my other bikes.  Converting it to 650c made the handling a little more responsive, with more stability a lower speeds due to the lower trail.  It also lowered the bottom bracket which theoretically stabilizes it on descents.  One problem, though was that the bike was built for racing and so it lacks fender and rack mounts.  I was using clip-on fenders, but those really aren’t adequate for riding through Portland’s winter rains.  So, I decided to try installing full coverage fenders, and to take advantage of its relatively low trail by mounting a front rack so that I could use a rando bag.

fender mounts fender zip tie

In order to mount fenders to a frame with no eyelets, p-clamps normally work pretty well.  The fork was fairly slender at the base but I shimmed the clamps and got them to hold.  The rear mounts were more difficult.  The seat stays on this bike are very small diameter, and even with a shim, the p-clamp could not grip the stay.  Instead, I used 3 zip ties and mounted them to the hole in the Gipiemme dropouts,  with one of the ties serving as a block to the open loop of the stays.

Planet Bike fenders

I like these Planet Bike Cascadia fenders.  They have dual stays front and rear which makes for 4 mounting points at the rear and 3 in the front.  Plus, they have nice long mud-flaps which really help keep your feet, drive train, and other riders drafting behind you dry.  Because this bike uses recessed brake nuts, I needed to find a way to mount the fenders to the brake bridge and fork crown.  On the front, I simply mounted the fender in front of the fork crown, but for the rear I needed Sheldon Brown’s “fender nuts“.  I didn’t want to wait around for a shipment, so I made my own by tapping 6 x 1 mm threads into the 5 mm nut head.  I didn’t tap too far down, and used a short bolt, so that I wouldn’t compromise the allen head at the base of the inside of the nut.

made by Wilken inspired by Sheldonfender spacer

Then I needed a pretty big spacer at the chain stays to make the fender line right (the fenders were designed for 700c wheels) and also to allow enough room for the front derailleur to move freely.  This set-up is a bit “spring loaded” with pressure from the rear fender going toward the seat tube.  If it starts to rattle, I’ll try something else.  The chain stay bridge was not drilled so I fashioned a hook to insert from underneath the frame.

Mounting the Nitto front rack was a breeze.  It is fully adjustable and should fit just about any kind of front end.  Good job, Nitto.

cloth bar tapebar end lights

For the rest of the build, I re-taped the bars with more conservative black tape, using the traditional method of starting at the stem and working toward the bar-ends.  In this way, there’s no ugly electrician’s tape, but you need solid bar end plugs to make it work well.  I have these nifty bar end lights, and although they don’t put out a ton of light, they definitely help others see me while riding at night.  Of course I use a head and tail light as well.

Tektro long reach brakes 2013-11-07 001 011 2013-11-07 002 002

I swapped out the white Tektro long reach brakes (Model R556) for some silver ones, but kept the rest of the build the same, including the Campagnolo Record head-set, bottom bracket, and Centaur crankset.  I am using Shimano shifters and derailleurs in friction mode and this bike shifts quicker and more silently than any other bike I own.

700c to 650c conversion

I am pleased with the bike’s new look and new utility.  Being able to use a front bag (Velo-Orange model shown above) will be really nice.  And commuting through the winter on this bike will be much more enjoyable with the full coverage fenders.