Something About Titanium Bicycles

Since entering industrial production, titanium and bicycles have forged an indissoluble bond. The application of titanium and titanium alloys in bicycles began in Japan. In 1999, the folding bicycle of the National Bicycle Industry Company was the lightest bicycle in the world at that time. Its mass was only 6.50kg. The trade name is “ToRenKuRu 6500”. The bicycle uses both a titanium alloy frame and industrial pure titanium structural parts.

Generally, 70% to 80% of the transmission structure parts and brake parts of light bicycles are made of aluminum alloy, and 20% are made of steel. The structural parts made of titanium alloy that can be used on bicycles are frames, variable speed gears, brake discs, etc. At present, the structural frames made of titanium alloy are mainly used in racing cars and high-end cars. Generally, bicycles use 36 spokes, while titanium alloy bicycles only have 24 spokes. The reduction in the number of spokes not only reduces the quality of the car, but also reduces wind resistance. Bicycle frames can be manufactured with industrial pure titanium tubes, or titanium alloy Ti-6Al-4V, Ti-6Al-4VEL1, and Ti-3Al-2.5V pipes can also be used. The titanium frame is lighter than the chrome-molybdenum alloy steel frame, and it is more comfortable to ride and has a longer service life. The average quality of the titanium frame produced by Litespeed in the United States is only 1.5kg, but the price is more than 3,500 US dollars per unit. The Italian company Campagnolo (Campagnolo) uses titanium and titanium alloys to manufacture structural parts of racing cars, such as package transmission locks, left-handed nuts, pinless crank shafts, front and rear hub shafts, left and right pedal shafts, etc.

Bicycles produced in China are all over the world in various countries and regions. In 2021, China's bicycle production has exceeded 80 million units, and 69.26 million units have been exported, an increase of 14.9% year-on-year; the export amount is USD$55.108 billion, an increase of 40.2% year-on-year, achieving a double jump in volume and price. Chinese bicycle consumers are located in more than 140 countries and regions around the world, and there are a variety of models, including mountain bikes, shock-absorbing bikes, road sports cars, city bikes, performance bikes, folding bikes, snowmobilers, strollers, electric bicycles, etc. In terms of automotive metal materials, steel is the main material, accounting for about 55% of the total amount of materials, followed by aluminum alloys, magnesium alloys, titanium alloys, and composite materials. Although the quality of titanium and composite materials is good, they are prohibitive due to their high prices. The price of the frame made of Ti-3Al-2.5V pipe is USD$22,000 to USD$44,200 per pair, and the selling price of the entire bicycle is about USD$33,000 to USD$88,000. In 1985, the titanium frame had not yet come out; in 1990, the sales of the titanium frame were about 1.5 million US dollars; in 1995, the sales reached 5 million US dollars. The sales growth rate of titanium frame is slow, the main reason is the high price.

The titanium alloy used for bicycles is mainly Ti-3Al-2.5V, which is an American titanium alloy developed for the manufacture of aircraft structures. The Chinese brand is TA18. The main advantages of this alloy are low yield strength, easy processing and forming, strong corrosion resistance, and high fatigue strength. It is an α-type titanium alloy. This type of titanium alloy mainly contains α-stable elements. At room temperature, it is basically an α-phase titanium alloy, such as industrial pure titanium (TA0, TA1, TA2, TA3) and TA7. α-titanium alloy is mainly used in the manufacture of chemical, petrochemical and processing industries. When used in the above industries, the first consideration is the corrosion resistance and processability of the alloy. There are 4 kinds of industrial pure titanium (TA0, TA1, TA2, TA3), and its maximum impurity content is shown in Sheet 1. Ti-3Al-2.5V is also an α-titanium alloy. According to GB/T 3620, there are 7 kinds, and the detailed composition is shown in Sheet 2.