A connection system for connecting a shaft of a wind tower to a support surface comprising a foundation, said system comprising: - a shaft comprising: • a post with a first face and a second face, the first face being the outer face of the post and the second face being the inner face of the post, and a fixing end, the post being configured to be placed vertically on the support surface, • a plurality of bolts distributed in pairs on both first and second faces of the post such that each bolt of each pair of bolts is fixed on either the first face or second face of the post, • a flange located in the fixing end of the post and adapted for being fixed on the support surface, - a plurality of pairs of tendons, each tendon comprising: • a lower anchoring embedded in the foundation, • an upper anchoring, • at least one strand with a first end and a second end (D'), the strand extending from the upper anchoring to the lower anchoring, • a pair of sleeves (10, 10') for each strand, a sleeve fixed to the upper anchoring and a sleeve fixed to the lower anchoring, each sleeve (10, 10') housing a segment of the strand, and - a foundation cage covering at least a part of each strand and of the upper anchoring, embedding the plurality of pairs of bolts. - a shaft comprising: • a post with a first face and a second face, the first face being the outer face of the post and the second face being the inner face of the post, and a fixing end, the post being configured to be placed vertically on the support surface, • a plurality of bolts distributed in pairs on both first and second faces of the post such that each bolt of each pair of bolts is fixed on either the first face or second face of the post, • a flange located in the fixing end of the post and adapted for being fixed on the support surface, • a post with a first face and a second face, the first face being the outer face of the post and the second face being the inner face of the post, and a fixing end, the post being configured to be placed vertically on the support surface, • a plurality of bolts distributed in pairs on both first and second faces of the post such that each bolt of each pair of bolts is fixed on either the first face or second face of the post, • a flange located in the fixing end of the post and adapted for being fixed on the support surface, - a plurality of pairs of tendons, each tendon comprising: • a lower anchoring embedded in the foundation, • an upper anchoring, • at least one strand with a first end and a second end (D'), the strand extending from the upper anchoring to the lower anchoring, • a pair of sleeves (10, 10') for each strand, a sleeve fixed to the upper anchoring and a sleeve fixed to the lower anchoring, each sleeve (10, 10') housing a segment of the strand, and • a lower anchoring embedded in the foundation, • an upper anchoring, • at least one strand with a first end and a second end (D'), the strand extending from the upper anchoring to the lower anchoring, • a pair of sleeves (10, 10') for each strand, a sleeve fixed to the upper anchoring and a sleeve fixed to the lower anchoring, each sleeve (10, 10') housing a segment of the strand, and - a foundation cage covering at least a part of each strand and of the upper anchoring, embedding the plurality of pairs of bolts.