With the increasing prevalence of electronic controls, the permanently bonded-in ICS3 guide tubes are no longer required for proper shifting performance. Leaving them out simplifies electronic installation and saves weight.
Cervelo engineered BBstop to accommodate all shifting options (mechanical and electronic) in a single design. BBstop incorporates a stop in their Single-Bend bottom bracket guide, permitting the use of cable housing through the down tube. This stop prevents housing shift (fore-and-aft) and fixes the axial position of the housing where it enters and exits the frame for consistent bend radii.