What is chromoly steel



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Aluminum is used to make inexpensive and expensive bicycle frames and other components. Cheap aluminum types are relatively soft, not very resilient and are used to manufacture inexpensive frames. For this purpose, cold-hardening alloys with copper and magnesium are used, for example AlCuMg2. High-quality aluminum alloys for expensive bicycle frames are made from the thermosetting alloys AL-6061, AL-7005 or another type of aluminum with an alloy number above 7000. With these alloys, careful and lengthy heat treatment after the welding process is a prerequisite for a durable bicycle frame.

Chromium-Molybdenum-Steel (Cromoly)

High-quality steel alloy for bicycle frames, used in more expensive and heavy-duty bicycles. The technical designation is often used to indicate the alloy, e.g. 25CrMo4.


Bicycle frames made from cheap steel of simple quality have been marketed under the fanciful term "Hi-Ten" (abbreviation for "High Tension") for several years. This simple type of steel has a lower tensile strength compared to chrome-molybdenum steel, so Hi-Ten frames are heavier or less durable than high-quality frames made of chrome-molybdenum steel with the same durability or the same weight. This material is used for inexpensive bicycle frames.


Bicycle frames are made of Hi-Ten steel, chrome-molybdenum steel or aluminum, and very expensive frames are also made of carbon or titanium.