FRAME MATERIALS
Technology plays a large part in cycling, be it in design,
clothing or nutrition. One of the most considered choices for both
the novice and experienced rider is the frame. Manufacturers have
the option of building in steel, aluminium, carbon, titanium,
magnesium or even a combination. They can choose the tube thickness,
the way the tubes are bonded or welded and can control with great
accuracy the way the bike will feel when climbing, its stability
when descending and how comfortable it will be on a long ride.
Different materials have different weights, produce different
handling characteristics and have different prices. In this section
we’ll try to guide you through the material maze and explain why we
stock frames made in different materials and from different brands.
Steel:
For many of us ‘thirty somethings’ our first bike was made of
steel. Remember lusting after a Raleigh Record Ace and watching Team
Banana in the 70’s? Reynolds 501 and 531 tubing? Well, steel is
still around and for good reason. Mass-market children’s bikes and
cheaper commuter cycles use low quality, heavy steel to achieve a
very low price point and as a specialist road shop we leave this
market to the high street stores. However, high quality steel is a
great choice for a frame builder. It gives a 'classic' feel –
comfortable to ride with a little ‘springiness’ which is
particularly useful on the pock-marked British roads –and hence it
is used in the construction of many audax and touring bikes.
Surprisingly, a quality steel frame can weigh less than a medium
range aluminium one. This is down to the way the tubes are ‘butted’
together, which allows for a light, quality thin-walled steel tube
to be used. Steel is highly resistant to fatigue and is therefore
very durable if looked after.
Aluminium:
As aluminium is not as dense as steel, it makes for a generally
lighter frame. It is easy to work/machine, keeping costs down.
Different tube sizes, grades and mixes are used to give varying
degrees of stiffness and strength. Computer aided design coupled to
innovations in the manufacturing process have allowed frame builders
to create tubes that can be one profile and thickness at one end and
have completely different dimensions and thickness at the other,
which lowers weight and enhances performance. This can change
compliance and improve aerodynamics, using bladed tubes for example.
Aluminium tends to be used to make a stiff frame which is ideal for
racing, as very little of your energy is lost, although often it is
mated to a carbon rear end to soften the ride. Like steel, you can
find cheaper aluminium frames in high street stores at very low
prices but these normally give a very jittery and overly stiff ride.
Aluminium tends to suit heavier riders where a more compliant
material coupled to their greater mass would give an unacceptable
loss of energy in the frame. It has the downside of a shorter
lifespan than steel as the stiffness can cause stress fractures but
with modern production processes on the more expensive frames, this
is now a rarity.
Titanium:
Titanium has always been seen as an exotic and expensive material.
It is hard to work in to tubes, weld and paint, leading to higher
production costs and a tendency to be found in a natural bare metal
finish. Whilst cheaper titanium frames are finding their way on the
market, the top-end frames sit in the highest price bracket of all.
On the flip-side it has excellent corrosion resistance so doesn’t
need painting which keeps the weight down. High quality titanium
gives a good blend of power transfer, low weight and comfort making
it a popular choice for long distance riding. Two different grades
of titanium are generally used, 3AL/2.5V and 6AL/4V; the numbers
reflect the percentage mix of aluminium and vanadium. The former is
slightly 'whippy' like a good steel frame and gives a relaxed ride
while the latter can be made extremely light and stiff as large
diameter tubing can be utilized without a weight penalty. For
someone seeking a frame with the comfort and durability of steel,
the stiffness of aluminium and understated looks Ti is a tempting
proposition. In any case, titanium can be a bike for life.
Carbon:
Often called ‘the wonder material’, and around since the mid
eighties, carbon is still relatively new when compared with its
rivals. It’s also the material that causes the most confusion as it
can now be found at virtually all price points. Perhaps the most
important point to note is that there is a huge variation in grades
of carbon. Carbon tubes are constructed in layers mixed with resin. Cheaper carbon, which is visually indistinguishable from the
higher price tubing has a large amount of resin and often just a
couple of layers of carbon. This keeps costs low but makes the tube
more brittle and fragile; these are generally the frames that you
hear about breaking. Better quality frames use carbon with stronger
and lighter weaves that require far less resin in their structure.
One of the big benefits of a carbon frame is that it can be used to
make tubes and lugs of almost any shape and size; this gives the
potential to 'fine tune' different areas of a frame, such as a stiff
bottom bracket area and compliant top tube. A stiff head tube can
drastically improve acceleration and handling, while each tube can
be stiff in one direction and compliant in the other. Lateral
stiffness and vertical compliance alter ride quality, as does frame
geometry and wheel/tyre choice. Designs can vary from lugged to
single piece monocoque construction, giving a huge variety in ride
quality and performance.
Magnesium:
This is a much denser material than aluminium and it is imperative
that the quality of the manufacture is very high. This prevents
corrosion later in the frames life. This necessity puts off many
manufacturers and the high quality of work is reflected in the
higher cost. The ride feel is similar to super-high quality
aluminium, with good energy transmission and sharp handling if
matched with the right geometry.
Frame Geometry:
Most frames use a 'double triangle' design and have done for years.
The cycling racing governing body, the UCI, have strict rules for
geometry and weight of racing bikes used in the pro peleton. We
refer to most frame geometry using virtual or actual top tube length
(a lot of bikes have a sloping top tube), seat/head tube angles,
seat/head tube length and wheelbase. With variations of these
measurements, in addition to the different frame materials, the
geometry can be used to alter a frames intended use, eg longer
wheelbase for touring/audax use, shorter for road racing,
wishbone-shaped rear seat and chainstays for comfort, relaxed head
tube angle for less direct handling etc etc.
Frame size:
As we are all beautiful shapes and sizes, custom fitting is the
final factor in reaching the best frame for your intended use and
budget. You would be amazed the difference you get from moving your
saddle back or forwards a couple of millimeters (seriously), or
changing the length of your stem or the position of your foot on the
pedal, or the length of your crank. We could go on and on but the
best advice we can give is to visit us to be measured properly. We
offer superb pre-set geometry from four manufacturers and a custom
build service in nearly all materials, starting from £499. We are
professionally trained on our state of the art measuring jig and
we’ve got a lot of years of cycling experience to draw on (yes,
we’re getting old).
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