The Red E1 is SRAM's newest Flattop chain and the one you'll find on the current-generation Red AXS groupset — both the 12-speed road version and the 13-speed Red XPLR gravel setup. SRAM took the lightest and most durable chain they've ever made and made it lighter, using HollowPin construction that is lighter and stronger than a solid pin, plus cutouts in the outer and inner plates that drop 13g from the previous generation. If you're building or servicing a current Red AXS drivetrain, this is the chain that came on the bike.

Flattop is the key detail here. The technology enables a narrower chain with quieter operation and increased strength and durability , and it's what makes SRAM's 12-speed and 13-speed Red cassettes possible without widening the freehub or squeezing cog spacing. The flat profile on the top of the outer plates lets the chain sit deeper into the cassette teeth, and the practical result on the road is a quieter drivetrain and cleaner shifts under load.

The E1 is cross-compatible across the current Red platform — same chain for the 12-speed road groupset and the 13-speed Red XPLR gravel groupset. If you're running an older Red AXS setup with the previous Flattop chain, the E1 drops in as a direct upgrade without any other drivetrain changes. It is not compatible with SRAM's Eagle Transmission mountain groupsets or any 11-speed SRAM road drivetrain — those use different chain widths and profiles.... Read More