Di2

Digital Integrated Intelligence

FD

FD

Front Derailleur

FD-XX

Front Derailleur Model Code

HG

Hyperglide

HG-X

Hyperglide Extra

HTII

Hollowtech II

IG

Interactive Glide

RD

RD

Rear Derailleur

RD-XX

Rear Derailleur Model Code

SPD

Shimano Pedaling Dynamics

STI

Shimano Total Integration