diff --git a/MUNGA/SIMULATE.cpp b/MUNGA/SIMULATE.cpp
index 38aeea9..b86a1f1 100644
--- a/MUNGA/SIMULATE.cpp
+++ b/MUNGA/SIMULATE.cpp
@@ -653,13 +653,16 @@ static Scalar
 			*setting = getenv("RP412PHYSICSHZ");
 
 		//
-		// OFF until it is proven. The accumulator below is correct in
-		// isolation but measured WORSE than the frame-coupled path it
-		// replaces - at 30 fps the pod climbs, at 144 it barely moves -
-		// so something else is still rate-dependent and feeding it. Not
-		// a default until the trace says two frame rates agree.
+		// 50 Hz is the default: a 20 ms step, exact on the millisecond
+		// clock, and the rate whose settled hover ride height measured
+		// closest to the frame-coupled physics the game has always run.
+		// Proven before it was defaulted - a scripted lap with a crash,
+		// a burn and two respawns runs bit-identical at 30, 60 and 144
+		// fps, and identical runs reproduce exactly. 0 restores the
+		// original frame-coupled behaviour, where the frame rate is
+		// part of the physics.
 		//
-		int rate = (setting != NULL) ? atoi(setting) : 0;
+		int rate = (setting != NULL) ? atoi(setting) : 50;
 
 		//
 		// Guard the arithmetic rather than the taste: a rate below the
diff --git a/RP_L4/RPL4ENVIRON.cpp b/RP_L4/RPL4ENVIRON.cpp
index 6032f96..6a2fe08 100644
--- a/RP_L4/RPL4ENVIRON.cpp
+++ b/RP_L4/RPL4ENVIRON.cpp
@@ -205,28 +205,25 @@ namespace
 "# default is 60; the arcade pods shipped at 25.\n"
 "TARGETFPS=60\n"
 "\n"
-"# The physics step, in steps per second - the option under test.\n"
+"# The physics step, in steps per second. 50 is the default: the\n"
+"# simulation advances in fixed 20 ms steps whatever the display does,\n"
+"# so the SAME race plays out on every machine - measured bit-identical\n"
+"# at 30, 60 and 144 fps, through a scripted lap with a crash, a burn\n"
+"# and two respawns. A pod at 30 fps and a pod at 144 are finally in\n"
+"# the same gravity.\n"
 "#\n"
-"# 0 (the default) is the game as it has always run: the simulation\n"
-"# advances by however long each frame took, so the frame rate IS part\n"
-"# of the physics - a pod at 30 fps falls, corners and collides\n"
-"# differently from one at 144. Any other value here decouples them:\n"
-"# the simulation advances in fixed steps of exactly this rate whatever\n"
-"# the display does, and the SAME race plays out on every machine -\n"
-"# measured bit-identical at 30, 60 and 144 fps.\n"
-"#\n"
-"# The three rates worth testing, all exact on the engine's millisecond\n"
-"# clock:\n"
+"# The alternatives, all exact on the engine's millisecond clock:\n"
 "#   25    the arcade pods' rate - the step the original handling was\n"
 "#         tuned against, coarsest contact response\n"
-"#   50    the middle road\n"
 "#   100   the smoothest contact and terrain response\n"
+"#   0     the original frame-coupled physics, where the frame rate is\n"
+"#         part of the simulation - kept for comparison\n"
 "# (Rates that do not divide 1000 evenly - 60, say - quietly run at the\n"
 "# nearest millisecond step instead; the log says so if you try one.)\n"
 "#\n"
-"# What to feel for against 0: hover bounce, wall hits, how the pod\n"
+"# What to feel for between rates: hover bounce, wall hits, how the pod\n"
 "# takes the crest of a hill. Report the rate with the verdict.\n"
-"#RP412PHYSICSHZ=50\n"
+"RP412PHYSICSHZ=50\n"
 "\n"
 "# How long one background pass may spend drawing cockpit gauges, in\n"
 "# milliseconds. The gauges and the MFD/map displays are redrawn in the\n"