It seems silly to me that riding in km gains more XP than riding in miles. In the UK (US & Australia too I think), miles and MPH are the standard units - so that’s what I understand and therefore use.
100 miles = 160.9km
100 miles = 3000 XP
160 km = 3200 XP
70,000 XP (level 20) is 3500 km or 2333 miles. But 2333 miles is 3754km.
So it would be great if every 100 miles gave 230XP to bridge the deficit.