The Project:

Since June 2008 I have been riding a Giant TCR Alliance. Over the years I have swapped out many parts, and the bike is becoming like George Washington's axe. New handle, new head but still the same axe. How long will a composite frame last, with the carbon-alloy joins? Since I have been happily replacing parts as they wear out, the obvious question is this: instead of buying a new bike assembled, how much would it cost to buy a new bike piece by piece? Only one way to find out...

Sunday, March 24, 2013

How to Build a Bike

How to Build a Bike

Not many people truly build bikes; to do so would be to build the frame, and possibly the components, as well.  I do not have an engineering workshop, nor the expertise to craft what is now a high degree of precision engineering in the design and execution of a modern gear system. There are people who build their own frames, but they are typically building in steel, as aluminium and titanium require a higher level of expertise with welding. And no-one build carbon frames in their garage.

Frame construction aside, the rest is assembly.  For this project I have approached the ideal as closely as possible, designing my own frame to suit my own physical measurements and riding style.  A Chinese titanium engineering company built the frame, and all that remains is for me to assemble the many components into a working bike. 

The build began with the wheels.  Lacing rims is a practised skill, and a good how-to guide is (surprise) found on Sheldon Brown's site.  Even without reading this resource, the keys to success are patience, care, and methodical approach.  There is no real right or wrong lacing pattern - take a look at spoke lacing patterns of different bikes that you see, and a range of possibilities becomes evident.  

My front wheel is an unconventional pattern, with spokes paired at the rim from the same side of the hub, with a double cross-over tension pattern.  Tips that I can mention for wheel-building include these two gems.  To insert a nipple, screw a spare spoke into the flanged end of the nipple, and you can then poke the nipple through the rim hole, and a couple of turns will anchor it onto the wheel spoke.  You can then reverse-turn the spare spoke to release it.

Also, I prefer to lace all of the spokes through the hub first, and then start securing them to the nipples, one set at a time; you have four sets of spokes, two each side of the hub.  Inside-outside lacing, each set anchored at four-hole intervals around the rim.  The lacing pattern comes from the four-hole sequence around the rim holes.

For these two wheels, I used a wheel stand for the entire build, although in the past I have laced the spokes with the rim on my lap, and trued them with the hub mounted in my bike, using the brake pads to spot waves in the rim.  My rear wheel is a traditional lace pattern with alternating left-right hub sides to the rim, and I needed to use the frame to get the dishing centred.  
The rear wheel spokes are asymmetrical, owing to the inset of the freewheel.  Periodically I would dismount the hub, lay the rim across two padded surfaces, and push the hub in to realign the dishing.  A few times around the rim retensioning the spokes, and the rim was done, true and centred.

Now, back to the frame.  First on board was the cable guide.  Being under the bottom bracket and not really visible, it is easy to overlook.  Next, the fork and headset assembly.

Putting the headset, spacers and stem in place on the steering tube, in place in the head tube, Run a pencil around the top edge of the steering tube.  The tube needs to be cut off three mm down from the stem top edge.  To do this properly I knocked up a simple mitre box - three pieces of MDF glued and nailed to another MDF piece, each with a 30 mm hole bored and in line with each other.  To make the cut line visible, wrap a piece of masking tape around the tube, the tape edge along the pencil mark.  Measure 3 mm down from the edge of the tape, marking points as you rotate the tube.  Join the dots, and you have a cut line.  With the tube secured in the mitre box score around the tube with a fine-tooth hacksaw blade, and keep rotating the tube as you cut deeper.  When the tube is cut through, use a fine metal file to smooth down the rough edges, and then fold some 1000 grit sandpaper around the edge and smooth the edge flat, inside and out.

When reassembled, the top cap fits down into the 3 mm space between the top of the tube and the top of the stem.  The compression plug keeps it all nice and tight.  You can then tighten the stem, and bolt the bars to the front of the stem.  Suddenly, it begins to look like a bike...

The rear derailleur can be bolted on at any time, so now is good.  Before positioning the front derailleur, you must install the bottom bracket, and then the crankset.  You can now secure the front unit the correct distance from the top of the crank.

The brakes go on next.  It is always good to get the back end cable mounts in place first.  With the brakes on, slip the shifters onto the bars and tighten them into position.  You can now install the cables.  Now, mount the wheels into the drop-outs, with the cassette installed on the rear freewheel.

Mount the brake cables first, and hold the housings in place against the handlebar position grooves with a couple of turns of electrical tape.  Always get the housing cut with a cm to spare, so if you stuff up a housing cut you can still tidy it up.  When you cut the housing (always before pushing the cable through!) use a spoke to open up the squashed housing core.  Simply push the threaded end in and give it a couple of turns.  Run some grease over the length of the cable before you push it through.  
Secure the cable to the brakes, and ALWAYS read the manufacturer's instruction paper before doing anything.  This also give instructions on how to correctly set the cable tension.  Test the lever-brake action, and then cut the cable with about 5-7 cm to spare, and use some pliers to crimp the aluminium end cap onto the end of the cable.

Before connecting the gear cables, follow the manufacturer's instructions to set the top and bottom limits for the derailleurs. Install the chain, making sure that you have the right number of links (rear derailleur instructions have clear notes on how to do this for your own set-up).  For my build, I ended up removing four links.  You can now connect the gear cables, and if you have not taken any short-cuts the gears will need minimal tuning.  Mine needed a minor tweak to the rear cable barrel-end adjuster, and all was good, shifting up and down cleanly and positively.

All that remains is the cosmetic and practical bits.  RIm tape, tubes and tyres, saddle, seatpost and clamp, handlebar tape, and pedals.  All done, the bike is now assembled.

So, how does it ride?  Very smooth, and the fit is spot on.  After the first ride (93 km) I felt no fatigue at all, almost as if I hadn't been for a ride at all.  One would expect this, as I designed the bike to match my own physical measurements and riding style.  And that is something that you can only really achieve with a professional bike fit service, finding a bike to suit you.  I could quite likely have achieved a similar ride by finding a bike of the right size frame, and tweaking the set up to suit, but then, I would not be able to say that it was my bike - designed and assembled by myself - would I?

Saturday, March 9, 2013

It's a Fit-Up Job - Framed!

It's a Fit-Up Job - Framed!


A top-end carbon frame, with the same four
points as the Pedersen bike

Straight up, the frame is the heart and soul of any bike.  There are four main points - the head tube anchor for the steering, the saddle, bottom bracket for the crank, and the rear wheel dropouts.  If you plot those points on a piece of paper, you can then draw any means of connecting them.  The traditional diamond frame developed quite early in bike history, and remains the basic layout for the majority of bikes.  There have been experimental departures from the diamond frame, but they are rare, short-lived and frequently expensive; how they perform is often enhanced, but at a premium.

A frame can make or break a bike.  The materials used, tube lengths, union angles.  Each can subtly influence the feel of the ride, how you sit and ride, comfort over long rides, power transmission from legs to wheels.  How stiff is the frame?  Will it flex along its length, reducing stability around corners, or will it be so stiff that every bump and vibration is transmitted straight up to your backside, spine and wrists?  Materials, tube lengths and geometry define a frame and its performance, and that is what makes the name on the frame marketable.

If you ever buy a bike from a shop, or read reviews about bikes, one thing becomes clear - the group set, the wheels, bars, and anything else attached to the frame, are off-the-shelf items, all interchangeable.  What makes a bike unique to a brand is primarily the frame, and secondly what particular combination of components is used to make it work.  

Simply, you can have two or more different bikes from different companies, but all sharing the same components.  There is no such thing as brand-loyalty; what distinguishes brands is the frame design - tube lengths and angles, materials and dimensions.  Many riders know this fundamental truth, and build their own bikes, choosing the frame and components to suit.

When I began this project, my original intention had been to source a stock frame from an online dealer.  That plan changed.

The shift began when I was researching what stem to buy.  This is reasonably important, as for a bike set-up there are two aspects of a bike that can be controlled to alter the reach (distance from seat to handlebars).  These are the seat position - a few centimetres slide along the rails.  The other is stem length.  To get the right stem length from the start, I used an online bike-fit calculator.
My dimensions and fit calculator output.

There are a few pages that will give you the set-up dimensions that best suit your body and style.  The calculator that I used is at Competitive Cyclist.  There are other sites, and when I enter the same measurements they give equivalent results, so one can assume they are trustworthy.  besides, I have based a significant investment in that assumption.  Simply, the fit calculator leads you through a range of body measurements, with clear instructions on how to make the measurements accurately.  Follow the instructions, enter your numbers, and it gives you essential dimensions of both frame tubes and controllable set-up aspects for your own body, with choice of up to three different riding styles.

All good so far.  It gave me the correct stem length, and tube lengths for a frame.  So, what frame?  Regular searching online gave a range of frames and prices, ranging from steel audax frames and bare aluminium frames for really, very low prices, though to labelled carbon frames in excess of NZ$3000.  There were also some titanium frames out there (Lynskey frames, from NZ$2000 onwards).  Of note were some naked carbon frames from Asian factories selling direct online.
The pieces of a Trek carbon frame.
Before being glued together.

Thinking time - what frame material?  There is often an automatic assumption that carbon is the top-line material; all cyclists should aspire to a carbon frame. Yet there are many steel frames out there, many being made and sold new.  And carbon breaks in a crash (recall, I bought alloy handle bars because alloy will not break either in a crash or spontaneously from progressive strain and delamination).  A quick check showed that most carbon frames come in at around 1.2 to 1.7 kg bare weight.  If not carbon, then we are talking metal.

Metal frames have a characteristic called "yield".  Simply, if you ride over a bump the frame bends slightly, absorbing the impact, and its elasticity returns the frame to its original shape quickly.  This gives metal frames a smooth ride.  Steel is the strongest material, but is also the heaviest.  It can take a lot of punishment, and a well-crafted frame can still perform better under a pro cyclist than a standard carbon rig.  Aluminium is still tremendously popular, as it is very light.  Aluminium's drawback is its low strength compared to steel (its modulus is 30% that of steel - described in detail on the late Sheldon Brown's site), so to have comparable strength the tubes must be of greater width or thickness than steel, although the resulting frame is still much lighter than a comparable steel frame.

And then we get to Titanium.  Titanium had a brief reign as the ultimate frame material, dethroned by the introduction of lower-cost carbon once the industry became capable of producing large-volume runs of carbon frames - it was always a matter of time.  In terms of metal, Titanium alloy is almost as strong as steel, and almost as light as aluminium.  If you built two frames of identical tubing, one of steel and one of Titanium, they would be of similar strength, but the Ti frame would be half the weight, and half as stiff, so to compensate for the stiffness a thicker-walled tube is used.

So, all things considered, Ti makes sense.  I would get the smoothness of metal with the lightness of carbon, and it would never break, fatigue or have issues with progressive delamination of the fibre layers. A quick search on Alibaba revealed several Asian factories producing titanium frames.  An initial email query gave the response "$X for a frame, add $100 if we make one to your own design."

Own design.  I liked the sound of that.  The bike would truly be a personal ride.  So, how do I design a bike?  There has to be something on the web about how to do it.  The search gave the answer within seconds:  BikeCAD.  

BikeCAD is an online Java-based CAD application that has been developed by Bike Forest, a bespoke bike design company.  The free version, despite some limitations, allowed me to create my own frame design, incorporating all important details beyond the obvious tube lengths and angles.  Every dimension is tunable, and many key components, for example headsets and pedals, have industry-standard units pre-programmed, with design dimensions adjusted to suit.  
My bike design overview.

A lot of tweaking, double-checking, cross-referencing and tweaking again gave me my frame design; using the bike fit key dimensions and my known components, and visual look (less compact and more traditional geometry - a blend of the two).  I then emailed the link to the CAD online file, a pdf of the design, and summary details of finer aspects of the frame to a few of the Chinese factories, collected quotes and haggled by email.

Some businesses don't want my business - slow replying (if at all), poor communication and little interest shown.  A couple of others were right on the ball - fast turnaround on replies, questioning anything that was ambiguous (often arising from Kiwi English to Second-Language English).  The business that impressed me the most was Xi'An Changda Titanium Products Company Ltd.   The rep took my CAD portfolio and created the factory AutoCAD version, made some tweaks, and made some last-minute adjustments to the head tube design once I had the headset and tube matched up and remeasured.  According to the company information the business was one of many set up by the Chinese government to support their developing aerospace industry and space program.  Making other titanium products, including bike parts, is just a part of their diversification.

Not quite the cheapest, but to get the order they lowered their price, quoting a total of NZ$1029.20 made and delivered.  So, that is less than half the price of a generic Ti frame, and made to my own design.  Compared to carbon frames, the price is similar to a mid-range generic frame, again not of my own design.

The frame arrived inside a few weeks, and I had the head tube reamed by a local engineering firm to ensure the integrity of the headset fit.  A wee oversight in the plan was the downtube mounts for shifter levers, but a pair of aluminium cable stops with barrel adjusters from the eBay seller chn_chou (NZ$24.29) not only fixed that issue, but improved upon it, placing the cables a bit further away from the downtube, and allowing an extra degree of tension adjustment.

Every bike needs a name, and after searching the net for examples of some appropriate names - protocol4, helix, halo, paradigm - they are all already being used.  Words lead on from each other, and recusant seems more appropriate, describing as it does a person who does not follow the mainstream.  In the past the word was also applied to heretics, who were often burned at a stake.  Hence the image for the headtube.  Adding Ti to the end identifies the frame material, and gives an Italian ring to it.



Frame decals were from Bikenames.com, and the frame finished with polyurethane clearcoat, the formulation for alloy wheelrims.  This is a durable, hard-wearing spray that is made to by applied directly to metal without a pigmented primer.  Final wet sanding with 1000 grit and a polish, and the frame is done.

Lovely.  Now I have to put it all together...

Friday, February 1, 2013

Odds and Ends - the Devil in the Details

Odds and Ends - the Devil in the Details

Ringo: "We're not great musicians. Just adequate."
Reporter: "Then how do you explain your popularity?"
Ringo: "Maybe people like adequate music."


Like the Beatles, a bike is greater than the sum of its parts.  Many parts are obvious - the frame, wheels, chain, handlebars, seat etc, but there are a few parts that tend to be overlooked, yet contribute significantly to the function and form of the bicycle.

Consider the headset.  Integral to the security of the headset is the tensioner bolt.  Most headset, including the one bought for this build project, come with the standard star-fangled nut.  This is an alloy disc that has been cut radially, and each section bent out slightly to form a shallow cone.  As the bolt running through its centre is tightened the disc expands against the inside of the steering tube, anchoring it securely through radial tension against the tube.  Further tightening of the bolt then draws the headset down towards the top of the steering tube.

This works wonderfully if the steering tube is steel or alloy, but if you have a carbon steering tube the star nut is trouble.  The outwards radial tension is concentrated along the edge of the disc, creating a zone of weakness that can cause the steering tube to fail.  This will not necessarily cause a face-planting crash, but it will destroy the fork unit, possibly the headset, and also the head tube.  If the head tube fails, you need a new frame.

The solution is an expansion plug.  This is simply a smaller analogue of the old quill stems.  Tensioning the headset bolt draws a cone bolt upwards into the plug, forcing its sections apart against a matching length of the steering tube.  So, instead of the tension force focussed along an edge, it is spread over a 30 mm length of the inside surface.

They are easy to find.  The unit that I bought was the Prestine plug from the ebay trader teamssx. The total cost to me was NZ$16.46.  Also from the same trader (same purchase order!) I bought a seat post clamp.

For many decades seat posts were secured by a bolt threaded through a flanged edge to the slot cut in the top of the seat tube.  Many cheaper steel bikes still use this system, as it is simple to create, and it is integral to the frame.  Also, home mechanics can maintain their kids' bikes by replacing lost bolts with any bolt that fits through the hole.

Modern bikes are made with a simple slot in the top of the seat tube, and the clamp sits on top of the tube.  For bikes where weight is not an issue a quick-release bolt is used to tension the clamp, but I have chosen a hex-head bolt.  The clamp provides tension that is distributed more evenly around the circumference of the seat tube than a quick release bolt, helping to preserve the integrity of the carbon seat post.

Ribble came to the fore for most of the remaining pieces.  These begin with the front derailleur clamp.

The front derailleur can be either bolted onto the frame, or clamped.  many frames are constructed with mounting studs integral to the seat tube, and it can be difficult to mount a clamp-on derailleur unit to a flattened stud mount.  Not knowing what frame I would end up with, I had bought a bolt-on derailleur.  if, as is now proving to be the case, the frame does not have the studs integral to the frame, you can buy a clamp which has a bolt flange for securing the derailleur unit.

This CSN unit was NZ$12.45, and came with the headset spacers, 10 mm alloy rings that provide extra height to the stem.  To secure the headset-stem-fork system the steering tube must be cut to the right length.  Once cut, cannot be uncut.  By trying different arrangements of spacers and stem you can find the right stem height for your riding style and comfort before committing to the final cut.  I chose alloy spacers, as carbon rings can compress slightly over time when the headset is tensioned, so your initial setting will gradually change as the rings squash.  The three 10 mm alloy spacers cost NZ6.74.


Handlebar tape is one way that riders can personalise their ride.  With tape being changed at least one every couple of years depending on usage and crash damage, a rider can change the colour and pattern of the whole front end of the bike.  Black is always safe, and doesn't show grease.  White tape does.  Titanium is a grey metal, and blue works with grey, so the Deda dark blue cork tape (NZ$15.29) is a good choice.

The last piece in the parcel is one which is rarely seen or even thought about.  The cable guide is secured to the bottom surface of the bottom bracket tube by a single screw.  Yet, it holds in place the cables for both derailleurs, and provides a smooth surface for the cables to move against.  And here is a touch of Italian - despite using Shimano components, the best deal I found (at Ribble) was the Campagnolo cable guide, for NZ$7.06.


For bikes, as with many other machines, it is only when you start looking closely at one that you begin to appreciate how many parts come together, and every bike has aits own, equally important function without which the operation of the machine will suffer, if not be severely compromised.  As with life, the devil is in the details.

Friday, January 4, 2013

Shifting the Posts - Goal Achieved

Shifting the Posts - Goal Achieved


Most bikes have two posts, both of them supporting major contact points, and both principal stress points on the bike.  Up front there is the fork and steering post unit, and most bikes have a seat post.  
Francesco Moser Time Trial Bike
I say most, because there have been some experimental designs that dispose of the seat post altogether and have the saddle mounted on the frame directly.  

Also, some top-end carbon time trial bikes have an aerodynamic seat post integrated into the frame itself.  The pillar is cut to suit the rider, and with all things carpentry, you can cut off but you cannot add on.  This typically involves a new frame.
Ridley TT bike with integrated seat pillar

The vast majority of us ride adjustable seat posts - a ring clamp around the top of the frame seat tube secures the seat post in place, and we can raise or lower the post at will.  Both directions.

The post that must be cut is the steering post, so if we are installing a new fork it is always a good idea to start with a high stem (and hence handlebar), and trim downwards until you find the handlebar height that suits you.  The only way to avoid this is to go retro, and use a quill stem that fits down the inside of the top of the steering tube and is held in place by a long expander bolt - this system is described in the post on stems, earlier on this site.

So, when installing the fork, the routine goes like this.  Fork crown race and bottom bearing cups for the headset.  Insert the steering tube up the inside of the head tube, and then drop in the top bearing cup and the top headset stack cover.
headset-stem assembly using external headset

You can  now, if you want low bars, slide the stem onto the steering tube, but it is wiser to slip on a couple of headset spacers before the stem, raising it a couple of centimetres (spacers are available separately in 2, 5, 10 and 20 mm thicknesses).

It is likely that there will be several centimetres of steering tube standing clear of the stem.  This is what you cut off, the cut being made about 3 mm below the top edge of the stem (how to do this will be described later).  With the shortened tube now assembled, the top cap expander bolt is inserted into the tube and tightened.

Because the top of the steering tube is below the edge of the stem, the top cap anchors against the spacer-stem stack, and with the anchor bolt inside the tube, the steering tube gets drawn up against the top cap, giving a nice, snug fit.

If you have an aluminium steerer you can use the star-fangled expansion bolt, but do not use one of these if you have a carbon tube, as the stress can damage the carbon tube.  Instead, use an expansion bolt that provides expansion stress evenly about the wall of the tube with no danger of localised stress fractures forming.  Considering that you lean forward onto the bars, you really do not want a tube failure.  This will result in your face meeting the road faster than you would really like.

So, what to look for in a fork?

How smooth a ride your bike gives depends on a few key factors.  Frame material and geometry is central to the overall quality of the ride, but all road feedback, bumps and all, come to the rider through the forks in the front, and the frame for the rear - seat and chain stays, both of which are connected to the seat tube and upwards through the seat post to the saddle.


sample pattern of carbon fibre lay-up
Up front, forks take the first hit of any bump in the road, and this is transmitted straight up the steering tube to the handlebars via the stem.  Metal forks absorb knocks and vibration through flexing, bending slightly on each impact.  However, the flexing, and the return of the fork material to its original shape, produces an irregular vibration that translates up to the bars.  Carbon composite forks, as with frames, are made of multiple layers of woven carbon fibre laid up and bonded with resin, similar in technique to fibreglass but significantly stronger and lighter.  The carbon components are much stiffer, with less flex, but more importantly the knocks and vibrations are dissipated through the layer interfaces, greatly minimising the vibration and chatter that makes it up to the handlebars, giving a much lighter feel to the front wheel.

Having ridden (and still ride) bikes with steel, aluminium and carbon forks, carbon has my vote.  There are many carbon forks out there, with many generic posts being produced in Asia, with a range of weights and geometries to match.  The forks that ended up on my table are Cannondale Synapse carbon forks, with carbon steering tube.  Weighing in at 350 gm, it is one of the lighter units out there, and cost a paltry NZ$141.05 from Bikewagon.  

As with many components, weight comes at a premium - cheaper forks are heavier.  Admittedly, Cannondale is an established brand, and I would trust it more than an unbranded, generic unit.  For such an important part of a bike, that is important, as failure is not an option.

SImilarly at the back end, a carbon seat post absorbs vibration the same as at the front end. It is perhaps of greater importance under the seat, as metal's ability to absorb bumps through flexing ceases to become relevant when the tube is not experiencing direct impacts.  Although the majority of tubes remain aluminium, carbon is becoming standard, and in order to increase compressive strength some posts are alloy wrapped in carbon.


Price is also relevant to weight, but is influenced by material, as new alloys can give a post of comparable weight to most carbon units.  The other consideration is the alloy mount for the saddle rails.  I prefer the adjustable offset.  The deal that I found was from Brinvo (who also sold me the bottom bracket).  Made by Felt, the 1.2SP3 seat post comes in at a relatively lightweight 205 gm and cost NZ$54.63.


So, front and back, the pillars that support the main contact points of hands and butt each have shared characteristics, function and material technology.  Not bad for woven tubes of carbon.