diff --git a/y2020/control_loops/superstructure/BUILD b/y2020/control_loops/superstructure/BUILD
index 803a65f..6ee38ad 100644
--- a/y2020/control_loops/superstructure/BUILD
+++ b/y2020/control_loops/superstructure/BUILD
@@ -200,3 +200,16 @@
         "//aos/network/www:proxy",
     ],
 )
+
+cc_binary(
+    name = "superstructure_replay",
+    srcs = ["superstructure_replay.cc"],
+    deps = [
+        ":superstructure_lib",
+        "//aos:configuration",
+        "//aos:init",
+        "//aos/events:simulated_event_loop",
+        "//aos/events/logging:log_reader",
+        "//aos/network:team_number",
+    ],
+)
diff --git a/y2020/control_loops/superstructure/superstructure_replay.cc b/y2020/control_loops/superstructure/superstructure_replay.cc
new file mode 100644
index 0000000..0148523
--- /dev/null
+++ b/y2020/control_loops/superstructure/superstructure_replay.cc
@@ -0,0 +1,76 @@
+// This binary allows us to replay the drivetrain code over existing logfile,
+// primarily for use in testing changes to the localizer code.
+// When you run this code, it generates a new logfile with the data all
+// replayed, so that it can then be run through the plotting tool or analyzed
+// in some other way. The original drivetrain status data will be on the
+// /original/drivetrain channel.
+#include "aos/events/logging/log_reader.h"
+#include "aos/events/simulated_event_loop.h"
+#include "aos/init.h"
+#include "aos/json_to_flatbuffer.h"
+#include "aos/logging/log_message_generated.h"
+#include "aos/network/team_number.h"
+#include "gflags/gflags.h"
+#include "y2020/constants.h"
+#include "y2020/control_loops/superstructure/superstructure.h"
+
+DEFINE_int32(team, 971, "Team number to use for logfile replay.");
+
+int main(int argc, char **argv) {
+  aos::InitGoogle(&argc, &argv);
+
+  aos::network::OverrideTeamNumber(FLAGS_team);
+  y2020::constants::InitValues();
+
+  // open logfiles
+  aos::logger::LogReader reader(
+      aos::logger::SortParts(aos::logger::FindLogs(argc, argv)));
+  // TODO(james): Actually enforce not sending on the same buses as the logfile
+  // spews out.
+  reader.RemapLoggedChannel("/superstructure",
+                            "y2020.control_loops.superstructure.Status");
+  reader.RemapLoggedChannel("/superstructure",
+                            "y2020.control_loops.superstructure.Output");
+
+  aos::SimulatedEventLoopFactory factory(reader.configuration());
+  reader.Register(&factory);
+
+  aos::NodeEventLoopFactory *roborio =
+      factory.GetNodeEventLoopFactory("roborio");
+
+  roborio->OnStartup([roborio]() {
+    roborio->AlwaysStart<y2020::control_loops::superstructure::Superstructure>(
+        "superstructure");
+  });
+
+  std::unique_ptr<aos::EventLoop> print_loop = roborio->MakeEventLoop("print");
+  print_loop->SkipAosLog();
+  print_loop->MakeWatcher(
+      "/aos", [&print_loop](const aos::logging::LogMessageFbs &msg) {
+        LOG(INFO) << print_loop->context().monotonic_event_time << " "
+                  << aos::FlatbufferToJson(&msg);
+      });
+  print_loop->MakeWatcher(
+      "/superstructure",
+      [&print_loop](
+          const y2020::control_loops::superstructure::Position &position) {
+        LOG(INFO) << print_loop->context().monotonic_event_time << " "
+                  << aos::FlatbufferToJson(position.hood());
+      });
+  print_loop->MakeWatcher(
+      "/superstructure",
+      [&print_loop](
+          const y2020::control_loops::superstructure::Status &status) {
+        if (status.estopped()) {
+          LOG(INFO) << "Estopped";
+        }
+        LOG(INFO) << print_loop->context().monotonic_event_time << " "
+                  << aos::FlatbufferToJson(status.hood());
+      });
+
+  factory.Run();
+
+  reader.Deregister();
+
+  return 0;
+}