If you have ever forgotten to stop your Garmin device after a ride or spent the first ten minutes doing loops of the carpark waiting for everyone to get going and wanted to crop these sections out of your Strava rides, then Strava does actually allow you to crop the beginning and/or end of a ride. It will then recalculate all your critical stats, like average speed, distance, max speed etc. Here's how

1. Open Strava

2. Click on the ride you want to crop

3. Click on the "Actions" tab (sort of bottom right corner of screen)

4. From the drop down menu choose "Crop Ride"

5. A new screen opens up.

6. Use the slider at the top of the page to crop the beginning and end of the ride. You will see the start and finish points move on the map (its best to zoom in on the map to be sure where you have cropped to)

7. When you are done. Click "Crop"

Be warned, this is a permanent change and you can't "Undo".