How to use Tempowatt
Tempowatt calculates the time of a bike trip from the terrain, the bike and its motor. This page goes through the calculator panel in order, from top to bottom.
1. Draw the route
Type the starting address, then the destination, and choose a suggestion from the list. You can also click the map: the first click sets the start, the second the finish. The time appears as soon as both points are placed.
- The crosshair in the start field starts from your current location.
- The arrows to the right of the fields reverse the route.
- The markers can be dragged on the map; the route is recalculated at once.
- New route clears the points to start again.
2. Add stops
A stop makes the route pass through a place. There are two ways to add one:
- Add a stop opens a new field: type the address, or click the map to place the stop.
- Once the route is drawn, clicking the map adds a stop directly. It goes where it lengthens the route the least.
Stops are numbered in route order, on the map and in the fields. The cross to the right of a field removes the stop. A route can have up to eight stops.
3. Choose the bike
Start with the category:
- 25 km/h: the common e-bike. Assistance stops at 25 km/h; above that, only the rider moves the bike.
- 45 km/h: the speed pedelec, assisted up to 45 km/h. In Switzerland it carries a yellow number plate and its rider wears a helmet.
Then choose the model, which sets the bike's weight, the riding position and the type of tyres, and the motor. If your motor is not in the list, take the closest one and correct its values in the technical settings.
Stromer bikes
Stromer bikes are listed with the speed pedelecs, each with its own motor and battery. Their motor sits in the rear wheel hub: it drives the wheel directly, without going through the gears. Compared with a motor at the cranks:
- on the flat and on gentle slopes, it easily holds a speed close to 45 km/h;
- on steep climbs, it loses force at low speed and climbs more slowly;
- it recharges the battery a little on descents and before each stop.
Their three assistance levels, 1, 2 and 3, replace the Eco to Turbo modes.
4. Assistance mode
The mode sets how much the motor adds to your own effort: Eco saves the battery, Turbo gives the most. The gap between modes is small on the flat and large on climbs. The Same route, other settings section at the bottom of the result gives the time in each mode.
5. Adjust technical settings
This section is folded at first. Its default values suit an everyday trip without luggage.
| Setting | What it changes |
|---|---|
| Power, torque, maximum assistance | The values of the chosen motor. Change them for a motor that is not in the list; "factory values" restores them. |
| Rider weight, luggage and passenger | The total weight, which matters most on climbs. |
| Rider effort | The power you put in when pedalling: about 70 W for a leisurely ride, 120 W at a moderate pace, 200 W when riding hard. |
| Battery | Its capacity in watt-hours, shown on the battery. |
| Stops and traffic | Time lost at traffic lights and junctions, from no stops to city centre. |
| Wind | Its speed and direction. The button on the right fetches the wind measured at the start. |
6. Read the result
- The time, in large type, stops included, with the distance and the average speed.
- Battery, use and range: the share of the battery used, and the distance a full charge would cover at the same pace.
- Split times, when the route has stops: the time elapsed at each stop and the duration of each leg.
- The route profile: the elevation along the route, darker where the riding is slow. Hovering over it shows the speed, gradient and motor power at each point, and the matching point appears on the map.
- Same route, other settings: the time in each mode and in the other category.
How the time is worked out
The route is split into short sections. On each one, Tempowatt calculates the speed at which the rider's effort and the motor's help make up for the gradient, tyre friction and air resistance. The travel time is the sum of the section times, plus an estimate of stops.
The route follows the roads and cycle paths of OpenStreetMap. The elevation and surface of each section come from the same data.
Accuracy
The time shown is an estimate: fitness on the day, traffic and the actual weather make it vary. It is most useful for comparing choices on the same route, such as an assistance mode, a bike or a category.
If a time looks wrong on a route you know, report it through the contact page, giving the start, the finish and the bike you chose.