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What are the differenes between A1, M4, E5, and M5 aluminium?

Last Updated: Oct 31, 2013 11:01AM PDT
A1 alloy is our workhorse 6061 frame material, employed extensively since 1995. The advantage of this material is the high level of control our engineers have over the production process. Minute differences in alloy mixture, tube dimensions, and heat treating are applied to specific areas of the bike. This allows advanced tube shaping at more attainable price points for added compliance and lighter weight.

M4 alloy is the mountain version of E5; it uses the same allow with different tube shaping and butting profiles to handle the more extreme loads of mountain application. Approximately 30% stronger than A1 alloy, the additional strength means less material can be used for significant weight savings.

M5 alloy is a complex mixture of the best alloys for a specific job and is a higher-grade 6000-series alloy. When building an M5 tubeset, the most appropriate alloy is used for each section of the bike to balance strength and weight requirements. For example, a mountain bike down tube supports a tremendous amount of load during its life, so a very strong and fatigue-resistant alloy is optimal for this application. On the other hand, the top tube carries a relatively small load, so a lighter alloy can be used in this area.

E5 alloy is a proprietary alloy which allows our engineers unmatched freedom to manipulate the inner and outer shapes of the tubing. However, the biggest advantage of the E5 is it's weld-recovery properties. Aluminium in any form does not like to be heated and cooled much. What makes E5 special is the phenomenal strength it possesses at the joint after welding. Under normal conditions bikes don't fail in the middle of a tube unless they are engineered poorly, so this stronger joint means overall frame strength can be improved with less material.

In summary:

A1
  • gets the job done well; function is the focus
  • 6000-series alloy
  • entry level
  • allows for butting of tubes and can be manipulated as needed
M4
  • takes ordinary to the extraordinary!
  • higher-grade 6000-series alloy
  • 15% higher tensile strength than A1
  • allows more aggressive tube shaping and butting
  • better weight and ride quality
M5/E5
  • Now you've reached amazing!
  • custom-blend alloy
  • 15% higher tensile-strength than M4
  • most aggressive butting
  • best weight and ride quality
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