Internal cable routing looks clean until you actually try to route a wire through a bare frame port and realize the opening is loose, unsealed, and ready to funnel road spray straight into your frame. Shimano's SM-GM02 grommet solves that final detail on Di2 builds, filling the 7x8mm oval cable ports found on many internally routed frames and locking the EW-SD50 E-Tube wire in place as it passes into the frame interior. Each pack includes four rubber grommets, which is enough to handle most builds with a spare or two left over.

The oval shape matters here. Frame manufacturers spec oval ports when they need a bit more real estate through a single entry—sometimes for routing flexibility, sometimes to accommodate a Di2 wire alongside a shift or brake line. If you've popped a port cover off your down tube or chainstay and measured a 7x8mm oval, this is the grommet that fits. Round 6mm holes take the SM-GM01 instead, so measure before ordering or check with the frame manufacturer if you're not sure.

Beyond just filling the hole, the rubber construction grips both the frame opening and the wire itself, which keeps the E-Tube from shifting or vibrating against the frame walls on rough roads. It also creates a weather seal that blocks water, wash spray, and fine grit from finding their way into the frame interior—something that matters more than most riders realize until they pull a bar tape wrap off a few seasons in and see what's built up inside.