When you're cycling, hills are the enemy. Google Maps now has a handy new option which shows the elevation for cycling directions, helping you identify less taxing routes.
If you search for cycling directions, you'll now see an elevation graph which indicates relative gradients. (If the route has no notable hills, you'll see "Mostly flat" as a description.) If multiple routes are on offer, you can factor the presence or absence of tough climbs into your plans.
Sometimes you won't have a choice and sometimes you'll want to challenge yourself, but the information is a useful addition to the cycling mix. Note that right now it only works on the desktop version, so it's one to pull out before you pop your helmet on.