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3x drivetrain for 10 speed Shimano mtb.

Tiagra 4700 is the lastest Shimano 3x10 groupset.

A ST-4703-L left shifter with FD-4703-B/F front derailleur is needed for a triple setup.

The rear derailleur needs to be a Tiagra RD-4700-GS with the long cage, or any compatible 11 speed derailleur.
More info about Tiagra 4700 w/ 11 speed derailleurs.

Tiagra 4700 series parts are not compatible with older Shimano 10 speed, due to a different cable pull.

Use any 9/10 speed crankset.

Tiagra rear derailleurs have the same actuation ratio as Shimano 11 speed rear derailleurs, so you can use them with Tiagra 4700 10 speed shifters.

The cable pull on the shifters is different than an 11 speed, so this setup will only work on a 10 speed cassette.

The Tiagra 4700 rear derailleur works just fine, but you can replace it with a lighter one, or one with a Shadow+ clutch.

Shimano 9 speed components all had the same cable pull. 10 speed road and mtb parts are no longer compatible, but a 9 speed mtb derailleur will work perfectly with a 10 speed shifter.

Tiagra 4700 is a 10 speed system with a different cable pull than the rest of the lineup.

GRX is 10 speed, and the 400 series is compatible with Tiagra 4700.

Tiagra RD-4700 rear derailleurs have a short cage (SS 28T) and medium cage (GS 34T). You can use the GRX RD-RX400 rear derailleur with Tiagra ST-4700 shifters to run a 36T cassette. The GRX has a Shadow+ clutch for better offroad performance.

Tiagra 4700 front derailleur is a better fit for road frames and chainrings up to 52T.