The Pinhead seatpost locks for GSD & HSD prevents removal of your seatposts. Once installed, the seatpost locks remains permanently on your bicycle, even when you ride. When you need to adjust your saddle height, your Pinhead tool lets you do this quickly and easily with a 15mm wrench. Pinhead locks cannot be removed with tools such as hammers, pliers, picks, universal socket tools, grinders or bolt cutters. Our convex disc technology prevents your parts from being removed by bike thieves.  Each key is different, and comes engraved with a nine-digit code so it can be replaced if lost. With your key code matching locks can be ordered to protect your other components or other bikes. All components are precision forged from corrosion-resistant CrMo steel and aircraft aluminium alloys. Pinhead locks are unmatched in quality, and backed by lifetime warranty.

Please note this fits Tern HSD, and GSD Gen 1 bikes only. All 2021 and newer GSD bikes require a larger lower seat clamp.