diff --git a/package-lock.json b/package-lock.json
index c6c5209..6a3afe8 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -959,6 +959,51 @@
         "to-fast-properties": "^2.0.0"
       }
     },
+    "@sinonjs/commons": {
+      "version": "1.8.1",
+      "resolved": "https://registry.npmjs.org/@sinonjs/commons/-/commons-1.8.1.tgz",
+      "integrity": "sha512-892K+kWUUi3cl+LlqEWIDrhvLgdL79tECi8JZUyq6IviKy/DNhuzCRlbHUjxK89f4ypPMMaFnFuR9Ie6DoIMsw==",
+      "dev": true,
+      "requires": {
+        "type-detect": "4.0.8"
+      }
+    },
+    "@sinonjs/fake-timers": {
+      "version": "6.0.1",
+      "resolved": "https://registry.npmjs.org/@sinonjs/fake-timers/-/fake-timers-6.0.1.tgz",
+      "integrity": "sha512-MZPUxrmFubI36XS1DI3qmI0YdN1gks62JtFZvxR67ljjSNCeK6U08Zx4msEWOXuofgqUt6zPHSi1H9fbjR/NRA==",
+      "dev": true,
+      "requires": {
+        "@sinonjs/commons": "^1.7.0"
+      }
+    },
+    "@sinonjs/formatio": {
+      "version": "5.0.1",
+      "resolved": "https://registry.npmjs.org/@sinonjs/formatio/-/formatio-5.0.1.tgz",
+      "integrity": "sha512-KaiQ5pBf1MpS09MuA0kp6KBQt2JUOQycqVG1NZXvzeaXe5LGFqAKueIS0bw4w0P9r7KuBSVdUk5QjXsUdu2CxQ==",
+      "dev": true,
+      "requires": {
+        "@sinonjs/commons": "^1",
+        "@sinonjs/samsam": "^5.0.2"
+      }
+    },
+    "@sinonjs/samsam": {
+      "version": "5.2.0",
+      "resolved": "https://registry.npmjs.org/@sinonjs/samsam/-/samsam-5.2.0.tgz",
+      "integrity": "sha512-CaIcyX5cDsjcW/ab7HposFWzV1kC++4HNsfnEdFJa7cP1QIuILAKV+BgfeqRXhcnSAc76r/Rh/O5C+300BwUIw==",
+      "dev": true,
+      "requires": {
+        "@sinonjs/commons": "^1.6.0",
+        "lodash.get": "^4.4.2",
+        "type-detect": "^4.0.8"
+      }
+    },
+    "@sinonjs/text-encoding": {
+      "version": "0.7.1",
+      "resolved": "https://registry.npmjs.org/@sinonjs/text-encoding/-/text-encoding-0.7.1.tgz",
+      "integrity": "sha512-+iTbntw2IZPb/anVDbypzfQa+ay64MW0Zo8aJ8gZPWMMK6/OubMVb6lUPMagqjOPnmtauXnFCACVl3O7ogjeqQ==",
+      "dev": true
+    },
     "@types/color-name": {
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/@types/color-name/-/color-name-1.1.1.tgz",
@@ -1832,6 +1877,12 @@
       "integrity": "sha1-+hN8S9aY7fVc1c0CrFWfkaTEups=",
       "optional": true
     },
+    "diff": {
+      "version": "4.0.2",
+      "resolved": "https://registry.npmjs.org/diff/-/diff-4.0.2.tgz",
+      "integrity": "sha512-58lmxKSA4BNyLz+HHMUzlOEpg09FV+ev6ZMe3vJihgdxzgcwZ8VoEEPmALCZG9LmqfVoNMMKpttIYTVG6uDY7A==",
+      "dev": true
+    },
     "doctrine": {
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/doctrine/-/doctrine-3.0.0.tgz",
@@ -3756,6 +3807,12 @@
         "verror": "1.10.0"
       }
     },
+    "just-extend": {
+      "version": "4.1.1",
+      "resolved": "https://registry.npmjs.org/just-extend/-/just-extend-4.1.1.tgz",
+      "integrity": "sha512-aWgeGFW67BP3e5181Ep1Fv2v8z//iBJfrvyTnq8wG86vEESwmonn1zPBJ0VfmT9CJq2FIT0VsETtrNFm2a+SHA==",
+      "dev": true
+    },
     "kind-of": {
       "version": "6.0.3",
       "resolved": "https://registry.npmjs.org/kind-of/-/kind-of-6.0.3.tgz",
@@ -3804,6 +3861,12 @@
       "integrity": "sha512-JNvd8XER9GQX0v2qJgsaN/mzFCNA5BRe/j8JN9d+tWyGLSodKQHKFicdwNYzWwI3wjRnaKPsGj1XkBjx/F96DQ==",
       "dev": true
     },
+    "lodash.get": {
+      "version": "4.4.2",
+      "resolved": "https://registry.npmjs.org/lodash.get/-/lodash.get-4.4.2.tgz",
+      "integrity": "sha1-LRd/ZS+jHpObRDjVNBSZ36OCXpk=",
+      "dev": true
+    },
     "loose-envify": {
       "version": "1.4.0",
       "resolved": "https://registry.npmjs.org/loose-envify/-/loose-envify-1.4.0.tgz",
@@ -4040,6 +4103,19 @@
       "integrity": "sha512-1nh45deeb5olNY7eX82BkPO7SSxR5SSYJiPTrTdFUVYwAl8CKMA5N9PjTYkHiRjisVcxcQ1HXdLhx2qxxJzLNQ==",
       "dev": true
     },
+    "nise": {
+      "version": "4.0.4",
+      "resolved": "https://registry.npmjs.org/nise/-/nise-4.0.4.tgz",
+      "integrity": "sha512-bTTRUNlemx6deJa+ZyoCUTRvH3liK5+N6VQZ4NIw90AgDXY6iPnsqplNFf6STcj+ePk0H/xqxnP75Lr0J0Fq3A==",
+      "dev": true,
+      "requires": {
+        "@sinonjs/commons": "^1.7.0",
+        "@sinonjs/fake-timers": "^6.0.0",
+        "@sinonjs/text-encoding": "^0.7.1",
+        "just-extend": "^4.0.2",
+        "path-to-regexp": "^1.7.0"
+      }
+    },
     "node-abi": {
       "version": "2.15.0",
       "resolved": "https://registry.npmjs.org/node-abi/-/node-abi-2.15.0.tgz",
@@ -4415,6 +4491,23 @@
       "integrity": "sha512-GSmOT2EbHrINBf9SR7CDELwlJ8AENk3Qn7OikK4nFYAu3Ote2+JYNVvkpAEQm3/TLNEJFD/xZJjzyxg3KBWOzw==",
       "dev": true
     },
+    "path-to-regexp": {
+      "version": "1.8.0",
+      "resolved": "https://registry.npmjs.org/path-to-regexp/-/path-to-regexp-1.8.0.tgz",
+      "integrity": "sha512-n43JRhlUKUAlibEJhPeir1ncUID16QnEjNpwzNdO3Lm4ywrBpBZ5oLD0I6br9evr1Y9JTqwRtAh7JLoOzAQdVA==",
+      "dev": true,
+      "requires": {
+        "isarray": "0.0.1"
+      },
+      "dependencies": {
+        "isarray": {
+          "version": "0.0.1",
+          "resolved": "https://registry.npmjs.org/isarray/-/isarray-0.0.1.tgz",
+          "integrity": "sha1-ihis/Kmo9Bd+Cav8YDiTmwXR7t8=",
+          "dev": true
+        }
+      }
+    },
     "performance-now": {
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/performance-now/-/performance-now-2.1.0.tgz",
@@ -4890,6 +4983,38 @@
         "simple-concat": "^1.0.0"
       }
     },
+    "sinon": {
+      "version": "9.2.0",
+      "resolved": "https://registry.npmjs.org/sinon/-/sinon-9.2.0.tgz",
+      "integrity": "sha512-eSNXz1XMcGEMHw08NJXSyTHIu6qTCOiN8x9ODACmZpNQpr0aXTBXBnI4xTzQzR+TEpOmLiKowGf9flCuKIzsbw==",
+      "dev": true,
+      "requires": {
+        "@sinonjs/commons": "^1.8.1",
+        "@sinonjs/fake-timers": "^6.0.1",
+        "@sinonjs/formatio": "^5.0.1",
+        "@sinonjs/samsam": "^5.2.0",
+        "diff": "^4.0.2",
+        "nise": "^4.0.4",
+        "supports-color": "^7.1.0"
+      },
+      "dependencies": {
+        "has-flag": {
+          "version": "4.0.0",
+          "resolved": "https://registry.npmjs.org/has-flag/-/has-flag-4.0.0.tgz",
+          "integrity": "sha512-EykJT/Q1KjTWctppgIAgfSO0tKVuZUjhgMr17kqTumMl6Afv3EISleU7qZUzoXDFTAHTDC4NOoG/ZxU3EvlMPQ==",
+          "dev": true
+        },
+        "supports-color": {
+          "version": "7.2.0",
+          "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-7.2.0.tgz",
+          "integrity": "sha512-qpCAvRl9stuOHveKsn7HncJRvv501qIacKzQlO/+Lwxc9+0q2wLyv4Dfvt80/DPn2pqOBsJdDiogXGR9+OvwRw==",
+          "dev": true,
+          "requires": {
+            "has-flag": "^4.0.0"
+          }
+        }
+      }
+    },
     "slash": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/slash/-/slash-2.0.0.tgz",
@@ -5483,6 +5608,12 @@
         "prelude-ls": "~1.1.2"
       }
     },
+    "type-detect": {
+      "version": "4.0.8",
+      "resolved": "https://registry.npmjs.org/type-detect/-/type-detect-4.0.8.tgz",
+      "integrity": "sha512-0fr/mIH1dlO+x7TlcMy+bIDqKPsw/70tVyeHW787goQjhmqaZe10uwLujubK9q9Lg6Fiho1KUKDYz0Z7k7g5/g==",
+      "dev": true
+    },
     "type-fest": {
       "version": "0.8.1",
       "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-0.8.1.tgz",
diff --git a/package.json b/package.json
index a9c87fc..41d75a5 100644
--- a/package.json
+++ b/package.json
@@ -29,6 +29,7 @@
     "@babel/plugin-transform-parameters": "^7.9.5",
     "@babel/preset-env": "^7.9.5",
     "eslint": "^6.8.0",
+    "sinon": "^9.2.0",
     "tape": "^5.0.0"
   }
 }
diff --git a/src/app/simulation.js b/src/app/simulation.js
index 25697e4..843acdd 100644
--- a/src/app/simulation.js
+++ b/src/app/simulation.js
@@ -59,7 +59,7 @@ export class Simulation extends EventEmitter {
     let now = Date.now();
     let timeSinceLast = now - this._lastPedalTime;
     let timeUntilNext = Math.max(0, this._interval - timeSinceLast);
-    let nextPedalTime = now - timeSinceLast + this._interval;
+    let nextPedalTime = now + timeUntilNext;
     this._timeoutId = setTimeout(() => {
       this.onPedal(nextPedalTime);
       this.schedulePedal();
diff --git a/src/test/app/simulation.js b/src/test/app/simulation.js
new file mode 100644
index 0000000..33c244e
--- /dev/null
+++ b/src/test/app/simulation.js
@@ -0,0 +1,143 @@
+import {test} from 'tape';
+import sinon from 'sinon';
+import {Simulation} from '../../app/simulation';
+
+test('constant cadence', t => {
+  const timeline = [
+    cadenceChange(0, 60),
+    pedalEvent(0),
+    pedalEvent(1000),
+    pedalEvent(2000),
+    pedalEvent(3000),
+  ];
+  
+  testTimeline(timeline, t);
+});
+
+test('start/stop/start', t => {
+  const timeline = [
+    cadenceChange(0, 60),
+    pedalEvent(0),
+    pedalEvent(1000),
+    pedalEvent(2000),
+    pedalEvent(3000),
+
+    cadenceChange(3001, 0),
+
+    cadenceChange(100000, 1000),
+    pedalEvent(100000),
+    pedalEvent(100060),
+  ]
+
+  testTimeline(timeline, t);
+});
+
+test('inconsequential cadence changes', t => {
+  const timeline = [
+    cadenceChange(0, 10),
+    pedalEvent(0),
+    pedalEvent(6000),
+    pedalEvent(12000),
+    cadenceChange(12001, 20),
+    cadenceChange(12002, 30),
+    cadenceChange(12020, 40),
+    cadenceChange(12100, 50),
+    cadenceChange(12150, 120),
+    cadenceChange(12499, 60),
+    cadenceChange(12999, 30),
+    pedalEvent(14000),
+  ]
+
+  testTimeline(timeline, t);
+});
+
+test('increase/decrease cadence', t => {
+  const timeline = [
+    cadenceChange(0, 10),
+    pedalEvent(0),
+    pedalEvent(6000),
+
+    cadenceChange(6001, 1000),
+    pedalEvent(6060),
+    pedalEvent(6120),
+    pedalEvent(6180),
+
+    cadenceChange(6181, 60),
+    pedalEvent(7180),
+    pedalEvent(8180),
+  ]
+
+  testTimeline(timeline, t);
+});
+
+test('varying cadence', t => {
+  const timeline = [
+    cadenceChange(0, 60),
+    pedalEvent(0),
+    pedalEvent(1000),
+    pedalEvent(2000),
+
+    cadenceChange(2001, 120),
+    pedalEvent(2500),
+    pedalEvent(3000),
+
+    cadenceChange(3100, 30),
+    pedalEvent(5000),
+    pedalEvent(7000),
+
+    cadenceChange(8999, 10),
+    pedalEvent(13000),
+    pedalEvent(19000),
+
+    cadenceChange(24999, 1000),
+    pedalEvent(24999),
+    pedalEvent(25059),
+    pedalEvent(25119),
+
+    cadenceChange(25178, 60),
+    pedalEvent(26119),
+  ]
+
+  testTimeline(timeline, t);
+});
+
+
+const C = 'CADENCE_CHANGE';
+const P = 'PEDAL_EMIT';
+const cadenceChange = (timestamp, cadence) => ({timestamp, type: C, cadence})
+const pedalEvent = (timestamp) => ({timestamp, type: P})
+const isPedalEvent = (evt) => evt.type === P
+const isCadenceChange = (evt) => evt.type === C
+
+/**
+ * Test that pedal events are emitted with the expected timestamps.
+ * @param {object[]} timeline - timestamped events (pedal or cadence change)
+ * @param {string} timeline[].type - event type P|C (pedal or cadence change)
+ * @param {number} timeline[].timestamp - millisecond timestamp
+ * @param {number} [timeline[].cadence] - cadence in rpm (only for cadence change event)
+ * @param {Test} t - tape test object
+ */
+function testTimeline(timeline, t) {
+  const timestamps = timeline.filter(isPedalEvent).map(e => e.timestamp);
+  const cadenceChanges = timeline.filter(isCadenceChange);
+  const duration = Math.max(...timestamps);
+
+  const clock = sinon.useFakeTimers();
+  const sim = new Simulation();
+
+  // change sim.cadence at the appropriate times
+  for (let {timestamp, cadence} of cadenceChanges) {
+    setTimeout(() => { sim.cadence = cadence; }, timestamp);
+  }
+
+  t.plan(timestamps.length);
+
+  let i = 0;
+  sim.on('pedal', (timestamp) => {
+    t.equal(timestamp, timestamps[i], `pedal event ${timestamp}`);
+    i++;
+  });
+
+  clock.tick(duration);
+  clock.restore();
+}