1 Cup of milk --> 300mg Calcium... vitamin D fortified for max absorbtion
http://www.nutritiondata.com/facts-B00001-01c21li.html

1 Cup of Brocolli --> 42.8 mg of Calcium --> 7 Cups of brocolli to get as much Calcium as Milk
http://www.nutritiondata.com/facts-B00001-01c20c0.html

1 Cup of Watercress --> 40.8 mg of Calcium --> 7.4 Cup of watercress to get as much Calcium as milk
http://www.nutritiondata.com/facts-B00001-01c20hq.html

to get your DV (1020mg) you can just down 2 cups of milk and get the rest of your DV from the rest of your diet.

you are just not going to be able to get you Calcium DV if you are trying to get it from green leafy vegetable and be able to do an endurance sport like cycling. how are you going to get enough macronutrients.. carbs, fats, and proteins when you are eating 14 Cups of brocolli or watercress a day...

when you are talking about vegetable, you can't just look at weight you have to look at volume. vegetables are very bulky with lots of undigestable fiber... lots of good micro-nutrients though

[Edit] this might be a way to go.. Calcium and Vitamin D fortified Orange Juice. same amount calcium as milk, plus vitamin D fortified for max absorption. i'm a little scared of soy after doing some research...
[Edit]

[Edit]ironically, Look at how much Vitamin C there is in brocolli... holy crap... maybe we should be looking to brocolli for our vitamin C instead of organgesEdit]