1. How does Velow calculate my travel expense?

Velow calculates the travel expenses for the rides you mark as a commute. Either flag the ride as a commute in Strava or in your Velow log.

2. What if I only want to record a percentage of my overall ride as a commute?

Velow allows you to edit the distance used for calculating the travel expense. If you go into the Velow Log and then edit the activity there is a field to amend the 'Commute Distance'.