LAPP is involved in the phaseII upgrade for the ATLAS pixels tracker [1]. The LAPP’s group is currently designing a pixels detector layout called Alpine Staves. This layout should allow to savematter in the detector. The silicon detectors should also cover a very high angle in the forward region.The pixel modules data transmission is an issue because of the very high number of channels and because of the high data rates. A first study in 2014 allowed to estimate the feasibility of data transmission and powering of the pixel modules along the staves thanks to multicore flexes. Discussions with manufactures have showed that the multicore solution is too complex in term of feasibility and cost. A simpler solution is a multiple flex made of several double‐sided cores. This study presents the methods and principles for a transmission flex based on the Alpine layout but results can be applied to a general stave‐based layout. A prototype has been produced in 2015 and test results show thecapabilities of a flex designed with real detector specifications.