diff --git a/src/bike.rs b/src/bike.rs
index d695ef3..9def5f6 100644
--- a/src/bike.rs
+++ b/src/bike.rs
@@ -6,15 +6,19 @@ use avian3d::{
         TransformInterpolation,
     },
 };
-use bevy::prelude::{
-    children, AlphaMode, App, Assets, Capsule3d, Color, Commands, Component, Dir3, EntityCommands,
-    Mesh, Mesh3d, MeshMaterial3d, Name, Plugin, Reflect, ResMut, SpawnRelated, Sphere,
-    StandardMaterial, Startup, Transform, Vec3, Visibility,
+use bevy::{
+    asset::Handle,
+    ecs::{bundle::Bundle, entity::Entity},
+    prelude::{
+        children, AlphaMode, App, Assets, Capsule3d, Color, Commands, Component, Dir3, Mesh,
+        Mesh3d, MeshMaterial3d, Name, Plugin, Reflect, ResMut, SpawnRelated, Sphere,
+        StandardMaterial, Startup, Transform, Vec3, Visibility,
+    },
 };
 
 use crate::physics::CatControllerState;
 
-pub const SPRING_CONSTANT: Scalar = 60.0;
+pub const SPRING_CONSTANT: Scalar = 50.0;
 pub const DAMPING_CONSTANT: Scalar = 10.0;
 pub const WHEEL_RADIUS: Scalar = 0.4;
 pub const REST_DISTANCE: Scalar = 1.5 + WHEEL_RADIUS;
@@ -97,87 +101,96 @@ fn spawn_bike(
         SleepingDisabled,
         CyberBikeBody,
         CatControllerState::default(),
-        ColliderDensity(1.2),
+        ColliderDensity(1.4),
         AngularDamping(0.2),
         LinearDamping(0.1),
         ExternalForce::ZERO.with_persistence(false),
         ExternalTorque::ZERO.with_persistence(false),
     ));
 
-    let color = Color::srgb(0.7, 0.05, 0.7);
-    let mut xform = Transform::default();
-    xform.rotate_x(FRAC_PI_2);
-    let pbr_bundle = (
-        Mesh3d(meshes.add(Capsule3d::new(0.5, 1.45))),
-        xform,
-        MeshMaterial3d(materials.add(color)),
-    );
-
-    body.insert(children![pbr_bundle]);
-
-    spawn_wheels(&mut body, meshes, materials);
+    let pbr_bundle = {
+        let color = Color::srgb(0.7, 0.05, 0.7);
+        let mut xform = Transform::default();
+        xform.rotate_x(FRAC_PI_2);
+        (
+            Mesh3d(meshes.add(Capsule3d::new(0.5, 1.45))),
+            xform,
+            Visibility::Visible,
+            MeshMaterial3d(materials.add(color)),
+            TransformInterpolation,
+        )
+    };
+    let parent = body.id();
+    body.insert(spawn_children(parent, pbr_bundle, meshes, materials));
 }
 
-fn spawn_wheels(
-    commands: &mut EntityCommands,
+fn spawn_children(
+    parent: Entity,
+    body: impl Bundle,
     mut meshes: ResMut<Assets<Mesh>>,
     mut materials: ResMut<Assets<StandardMaterial>>,
-) {
+) -> impl Bundle {
     let mesh: Mesh = Sphere::new(WHEEL_RADIUS).into();
+    let wheel_material = StandardMaterial {
+        base_color: Color::srgb(0.01, 0.01, 0.01),
+        alpha_mode: AlphaMode::Opaque,
+        perceptual_roughness: 0.5,
+        ..Default::default()
+    };
+
+    let mesh = meshes.add(mesh);
+    let material = materials.add(wheel_material);
 
     let front_rake = Vec3::new(0.0, -1.0, -0.9).normalize(); // about 30 degrees
     let front_wheel_pos = FRONT_ATTACH + (front_rake * REST_DISTANCE);
-
-    wheel_caster(
-        commands,
-        FRONT_ATTACH,
-        Dir3::new_unchecked(front_rake),
-        REST_DISTANCE,
-        CyberWheel::Front,
-    );
-    wheel_mesh(
-        commands,
-        &mut meshes,
-        &mut materials,
-        front_wheel_pos,
-        mesh.clone(),
-        WheelConfig::new(
-            FRONT_ATTACH,
-            REST_DISTANCE,
-            SPRING_CONSTANT,
-            DAMPING_CONSTANT,
-            FRICTION_COEFF,
-            WHEEL_RADIUS,
-        ),
-        CyberWheel::Front,
-    );
-
     let rear_rake = Vec3::new(0.0, -1.0, 0.9).normalize();
     let rear_wheel_pos = REAR_ATTACH + (rear_rake * REST_DISTANCE);
 
-    wheel_caster(
-        commands,
-        REAR_ATTACH,
-        Dir3::new_unchecked(rear_rake),
-        REST_DISTANCE,
-        CyberWheel::Rear,
-    );
-    wheel_mesh(
-        commands,
-        &mut meshes,
-        &mut materials,
-        rear_wheel_pos,
-        mesh,
-        WheelConfig::new(
-            REAR_ATTACH,
+    children!(
+        body,
+        wheel_caster(
+            parent,
+            FRONT_ATTACH,
+            Dir3::new_unchecked(front_rake),
             REST_DISTANCE,
-            SPRING_CONSTANT,
-            DAMPING_CONSTANT,
-            FRICTION_COEFF,
-            WHEEL_RADIUS,
+            CyberWheel::Front,
         ),
-        CyberWheel::Rear,
-    );
+        wheel_mesh(
+            mesh.clone(),
+            material.clone(),
+            front_wheel_pos,
+            WheelConfig::new(
+                FRONT_ATTACH,
+                REST_DISTANCE,
+                SPRING_CONSTANT,
+                DAMPING_CONSTANT,
+                FRICTION_COEFF,
+                WHEEL_RADIUS,
+            ),
+            CyberWheel::Front,
+        ),
+        wheel_caster(
+            parent,
+            REAR_ATTACH,
+            Dir3::new_unchecked(rear_rake),
+            REST_DISTANCE,
+            CyberWheel::Rear,
+        ),
+        wheel_mesh(
+            mesh,
+            material,
+            rear_wheel_pos,
+            WheelConfig::new(
+                REAR_ATTACH,
+                REST_DISTANCE,
+                SPRING_CONSTANT,
+                DAMPING_CONSTANT,
+                FRICTION_COEFF,
+                WHEEL_RADIUS,
+            ),
+            CyberWheel::Rear,
+        ),
+    )
 }
 
 //-************************************************************************
@@ -185,36 +198,27 @@ fn spawn_wheels(
 //-************************************************************************
 
 fn wheel_caster(
-    commands: &mut EntityCommands,
+    parent: Entity,
     origin: Vec3,
     direction: Dir3,
     rest_dist: Scalar,
     wheel: CyberWheel,
-) {
+) -> impl Bundle {
     let caster = RayCaster::new(origin, direction)
         .with_max_distance(rest_dist)
         .with_max_hits(1)
-        .with_query_filter(SpatialQueryFilter::from_excluded_entities([commands.id()]));
+        .with_query_filter(SpatialQueryFilter::from_excluded_entities([parent]));
 
-    commands.insert(children![(caster, wheel)]);
+    (caster, wheel)
 }
 
 fn wheel_mesh(
-    commands: &mut EntityCommands,
-    meshes: &mut ResMut<Assets<Mesh>>,
-    materials: &mut ResMut<Assets<StandardMaterial>>,
+    mesh: Handle<Mesh>,
+    material: Handle<StandardMaterial>,
     position: Vec3,
-    tire_mesh: Mesh,
     config: WheelConfig,
     wheel: CyberWheel,
-) {
-    let wheel_material = &StandardMaterial {
-        base_color: Color::srgb(0.01, 0.01, 0.01),
-        alpha_mode: AlphaMode::Opaque,
-        perceptual_roughness: 0.5,
-        ..Default::default()
-    };
-
+) -> impl Bundle {
     let xform = Transform::from_translation(position);
 
     let name = match wheel {
@@ -222,18 +226,18 @@ fn wheel_mesh(
         CyberWheel::Rear => "rear tire",
     };
 
-    commands.insert(children![(
+    (
         Name::new(name),
         config,
-        Mesh3d(meshes.add(tire_mesh)),
-        MeshMaterial3d(materials.add(wheel_material.clone())),
+        Mesh3d(mesh),
+        MeshMaterial3d(material),
         xform,
         Collider::sphere(WHEEL_RADIUS),
         ColliderDensity(0.5),
         CollisionLayers::NONE,
         TransformInterpolation,
         wheel,
-    )]);
+    )
 }
 
 pub struct CyberBikePlugin;