Join a ride your bike computer saved in two or more parts, after a restart or a flat battery. FIT, GPX and TCX go in; one TCX or GPX comes out, in time order, with the distance carried over. Your file is not uploaded.
Read in your browser. Your file is not uploaded.
The usual case is one ride saved as several files: the unit restarted, the battery was swapped at a café stop, or you pressed save instead of pause. Merging turns the parts back into one activity with one total distance and time.
It also works for a ride recorded partly on one device and partly on another, as long as the parts do not overlap much in time.
A valid FIT needs a correct session summary, lap messages and activity message written in the FIT binary layout, and a platform will reject one that is subtly wrong. TCX is the safer container: it keeps laps, distance, heart rate, cadence, speed and power, and training platforms accept it for upload.
Choose GPX instead if you only need the track for a mapping app. It keeps position, elevation and time, with heart rate, cadence and power in its extension fields.
Delete the separate parts from your training platform first. A merged ride covers the same time as the parts, and platforms that check for duplicates may refuse it while the parts are still there.
The file is read by JavaScript running in this browser tab. It is never uploaded: there is no server on the other end that could receive it, and the page makes no network request with its contents.
You can check that yourself. Open your browser's developer tools, go to the Network tab and drop a file in. You will see the page's usual requests, such as the site's analytics and, the first time you open a FIT file, the file reader loading. None of them carries your file.
The parts' own summaries (calories, Normalized Power) cannot simply be added up, so the result carries the records and laps, and your platform calculates the totals when you upload it.
If there are ten minutes between two parts, the merged ride has a ten-minute gap. The tool does not invent records to fill it; the result tells you how long each gap is.
Merging a ride with a run would produce one activity with one sport. Merge parts of the same activity only.
Drop both files on this page, check the order and press merge. The parts are joined by time, the distance continues from one to the next, and you download one TCX (or GPX) to upload as a single ride. Delete the separate parts from your platform first to avoid duplicates.
Yes. You can mix FIT, GPX and TCX files in one merge. GPX files usually have no distance field, so the distance is calculated from the positions.
Writing a FIT that platforms accept means writing a correct session summary in the binary format, and a small mistake there gets the file rejected. TCX keeps everything that matters for a ride, including laps and power, and training platforms accept it for upload.
The part that started first is kept, and the records of the later part that fall inside it are dropped. The result tells you how many were dropped, so you know whether the overlap was a few seconds or a real duplicate.
No. Reading and merging happen in your browser tab, and the files never leave your computer.
