Check on the bike: chain on the largest ring and largest cog, then add
| Drivetrain | Add |
|---|---|
| Shimano road 12-speed105, Ultegra, Dura-Ace | 2–3 links + QUICK-LINKUDH: 1–2 links + QUICK-LINK |
| Shimano GRX 12-speed 2xRD-RX820 | 3–4 links + QUICK-LINKUDH: 2–3 links + QUICK-LINK |
| Shimano GRX 12-speed 1xRD-RX822 | 4–5 links + QUICK-LINK |
| Shimano GRX Di2 12-speedRD-RX825 | 3–4 links + QUICK-LINK |
| Shimano GRX Di2 12-speed 1xRD-RX827, RD-RX717 | 5–6 links + QUICK-LINK6–7 links with a connecting pin |
| SRAM road 2x10, 11, 12-speed | 1 inner + 1 outer link |
| SRAM road 1x10, 11, 12-speed | 2 inner + 2 outer links |
| SRAM XPLR 13-speedFull Mount | No wrap: SRAM's guideby chainstay and chainring |
| Other or not surePark Tool | 1 in (2 rivets)1x, 42T+ cog: 2 in (4 rivets) |
A starting point. Confirm on the bike with your drivetrain maker's method. Shimano's count depends on which plate sits at the end of the wrap. Checking wear on the old one? Chain wear thresholds. Going to a bigger cassette? Check your derailleur capacity first. On GRX 12-speed? Which cassette, freehub and chain each GRX derailleur takes. Sources: Park Tool equation and sizing guide; Shimano dealer's manuals for road Di2, 105 RD-R7100, GRX RX820/RX822 and GRX Di2; SRAM chains manual.