Saturday, September 21, 2019

Framed again!!

 

 

By Matt Walthauer

Last issue I explained steel and aluminum bicycle frames and their pros and cons, now I will explain the next two popular materials and lastly the mystery frame material

Carbon Fiberplastic strengthened and reinforced by a graphite textile

Carbon fiber has become the most popular frame material used today; it is used in most higher end road racing frames and also higher end hybrid (a cross between mountain tire and road tire) and mountain bicycle frames. The tubing used to construct carbon frames is really quite different than used in metal frames; because of the fibrous nature it has a more pronounced grain than the metal materials, and can be molded and designed into many different ways. If a carbon frame is well designed and the fabric is aligned and wrapped in such a way it can provide quite a bit of strength. The biggest downfall to this is that bicycles are really subject to a lot of different types of stresses from all types of direction and carbon can become weak at certain points on the bicycle where metal is often used, like fork ends, bottom bracket shells (where the pedal arms meet the frame), headsets (what hold the stem and handlebar on the bicycle), and this in turn can lead to corrosion over time and may lead to failure. This is one reason why most touring bicycles are still commonly made from steel.

Carbon fiber bike frames can be constructed in few different ways; they can be made in one piece (monocoque) where the material is wrapped in many different directions to provide strength and lightness. Another way is that they are made like a traditional bicycle where the carbon tubing is joined directly into lugs. Both methods are good and strong and give a comfortable ride for long and short distances.

Some of the top carbon bicycle frame companies are Jamis and Fuji bicycles.

The Good

  • Can be stronger and lighter than steel and aluminum
  • Comfortable ride for all distances

The Bad

  • Fatigue and damage issues associated with long term use
  • Cannot be easily repaired if damaged
  • More expensive than steel and aluminum

Titanium

Today this frame material seems to be the the most exotic and expensive metal used for bicycle frame tubes. With that it does combine many of the top desirable characteristics, including a high strength (like steel) to weight (like carbon fiber) ratio and the best corrosion resistance. It also has a reasonable stiffness (about half that of steel) this allows for many titanium frames to be constructed with “standard” tube

Bamboo Cargo Bike. Submitted

Bamboo Cargo Bike. Submitted

sizes compared to that of the traditional steel frame, lately larger diameter tubing is becoming more common for added stiffness. Because of the reduced stiffness of the frame, titanium does have a whippy riding feel to them.

The best case for titanium is that if it made correctly it will last a lifetime. It is said if titanium does not break in the first month, it never will. Titanium is very light but will give you a hard ride, the most common thing is to mix titanium main tubes with carbon forks and also on the seat stays this would be the best for handling and for comfort. As many titanium frames can be much more expensive than similar steel alloy frames the cost can put them out of reach for many cyclists.

Some of the top titanium bicycle frame builders today are Merlin, Moots, Eriksen and Litespeed.

The Good

  • Most rugged
  • Least prone to crack or fatigue
  • Both light and stiff

The Bad

  • Most expensive

Those are the top four bicycle frames being used today, and there has always been others as well, some people have made frames from scandium, wood, and even pvc, but recently the most interesting and what I think is really fascinating is what a company called Calfee is using; Bamboo.

Bamboo is first and foremost a natural and renewable resource for making bicycle frames. The best characteristics that it has are its vibration dampening and crash tolerances. With that it does provide a very comfortable and smooth ride. Today there are many different ways to treat the bamboo to make it so it is durable, the main aim here is to completely dry the bamboo so it will change shape at a later time.

There are also many different ways to join the bamboo to make it into a complete frame; today the most popular method is using hemp fibers made into a lug type design to join these bamboo tubes. After completion the frames are then coated in satin polyurethane.

What is really interesting about bamboo bicycles frames is that for the most part they do not require electricity to build and no real investment in equipment. Recently a Craig Calfee of Calfee bicycle has been in Ghana and other developing countries to show residents how to build bamboo bicycles as a main source of transportation for themselves and movement of products.

Matt Walthauer, a Marco Island resident since 1985 is a graduate from Embry Riddle Aeronautical University, and is the owner of Island Bike Shop and Scootertown on Marco Island and Naples. He is also a member of the Marco Island bike path ad-hoc committee.

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