What's the difference between Shimano E-type and E2-type front derailleurs?

It's frustrating when companies sell you things that look the same, but give them different names.

So, in order to help others in the same situation, here's what I've found out about the E-type and E2-type bottom brackets from Shimano.

• E-type front derailleurs come with bottom bracket back plates
• E2-type front derailleurs don't come with a bottom bracket back plate
• Both are specific to the size of the chain-rings on the chain-set (with room for marginal change)
• Both have the same mounting holes (if you remove the back plate from the E-type)

S3 direct mount

Curiously, E2-type derailleurs are also known under the direct mount standard 'S3'. They both work with the same mounting holes and designs. As will a newer E-type with the back plate removed.

I'm yet to find any evidence than an E-type is different from an E2-type (except for the back plate). I would however recommend you purchase a compatible E2-type as there has to be a reason for the different naming convention, right? Guys?

Technical diagram

Below is a Shimano technical diagram showing the different versions from a standard front derailleur through each of the 'E' type configurations.

• No mount
• E with bottom bracket mount
• E2 mount
• E with no bottom bracket mount

Hope this helps someone!