This is just a code chunk and leafet map for a demo. It will work to expand the existing script on fstrava.

leaflet() %>%
  addProviderTiles(providers$CartoDB.Positron , group = "Positron (default)") %>%
  addProviderTiles(providers$OpenStreetMap    , group = "Open Street Map") %>%
  addProviderTiles(providers$Esri.WorldImagery, group = "World Imagery (satellite)") %>% 
  addPolylines(data = acts_line_sf %>% 
                 filter(act_id == act_i),
               color = "#fc4c02") %>% 
  addLayersControl(
    baseGroups = c(
      "Positron (default)",
      "Open Street Map",
      "World Imagery (satellite)"
    ))