Drivetrain

Drivetrain (Shimano GRX 1x 12 speed)

Bottom bracket: SM-BBR60 (threaded 68mm)

Crankset: FC-RX820-1 (40T): Crank arm length: 170 (Alt: 172.5 & 175); Chain line (mm): 49.7; P.C.D. (mm): 110; Q-factor (mm): 151; Weight: 644g

Cassette: CS-M8100-12 (10-51T)

Derailleur: RD-RX822-SGS

Control lever – right: ST-RX820-R

Control lever – left: BL-RX820-L

Chain: CN-M6100 (HG 12-speed)

The connecting link for the Shimano CN-M6100 12-speed chain is the Shimano SM-CN910-12 Quick-Link.
- REI: Shimano XTR SM-CN910-12 HG Quick-Link. $18
- Optional TL-CN10 pliers (not included) make connecting and removing even easier, while keeping your hands clean. [REI]
- Wolf Tooth Master Link Combo Pliers [REI]: The lightweight Wolf Tooth Components Master Link Combo Pliers multi-tool serves as a tire lever, valve core remover, valve stem lock nut wrench and master link pliers, and it stores 2 master links.
- Park Tool pliers

Brakes (Shimano GRX)

Brake caliper - front BR-RX820 (black)
Brake caliper - rear: BR-RX820 (black)
Rotors: RT-CL800 [x2]; Options: 140mm or 160mm (w/adapter)
Rotor adapter
Brake hose kit: SM-BH90-JK-SSR [x2]; 1700 or 2000mm?
Brake fluid: Shimano hydraulic

Compatible Shimano 12-Speed Chain Options

Shimano CN-M9100 (XTR / Dura-Ace grade): The top-tier 12-speed chain featuring SIL-TEC treatment, fully cross-compatible with Shimano 12-speed GRX drivetrains. $85

Shimano CN-M8100 (Deore XT / Ultegra / GRX grade): The standard or common tier choice for 12-speed GRX builds, featuring SIL-TEC ultra-low friction treatment and chromized roller link plates for off-road durability. Typically available in 126 or 138 link variants. $62

Shimano CN-M7100 (SLX / 105 / GRX grade): A budget-friendly 12-speed chain alternative that utilizes holes in the inner plates to match Dynamic Chain Engagement+ (DCE+) narrow-wide teeth. $39

Shimano CN-M6100 (Deore grade): An entry-level 12-speed Hyperglide+ chain option that also works with 12-speed GRX/MTB components. $30

Gear inches (650b X 50)

Standard GRX: 40 X 10-51 = 21 to 108 gear inches

Wolf Tooth 38T chainring (38 X 10-51) = 20 to 102 gear inches

Wolf Tooth 36T chainring (36 X 10-51) = 19 to 97 gear inches

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SRAM + Wolf Tooth: (38 X 10-52) = 20 to 102 gear inches

Questions

This is the proposed drivetrain. I have two remaining questions:

(1) What size crankarm should I get? I am 5’9 with a 32” inseam.

(2) Would a White Industries R30 crank substitute for the Shimano one, and what would the overall cost difference be?

Merlin

https://www.merlincycles.com/basket

$929.88