Di2

Digital Integrated Intelligence

FD-XX

Front Derailleur Model Code

GRX

Gravel RX

HG

Hyperglide

HG-X

Hyperglide Extra

HTII

Hollowtech II

IG

Interactive Glide

RD-XX

Rear Derailleur Model Code

SL-XX

Shift Lever Model Code

SPD

Shimano Pedaling Dynamics

STI

Shimano Total Integration