'Long after the African superstars have loped their way through Docklands, you can hear the crowds enthusiastically bellowing. 'Come on, Fairy, come on, girl, you can do it'. The London crowd are there for the rhinos as much as the record breakers .. ' so starts the chapter on crowd participation in John Bryant's The London Marathon The History of the Greatest race on Earth - a wonderful book that I am currently reading(borrowed from Dharmendra a while ago).
The above applies very much to Mumbai marathon as well.
Borrowing further from the book(replacing London by Mumbai):
The spectators really can keep you going when your body screams to stop. The spectators seem to put as much effort into supporting as the runnerd do into running.For this one day Mumbai simply stops, stands on the pavement and cheers. The spectators have a seemingly unending supply of sustenance for the runners: water, fruit juices, soft drnks, bananas, oranges,biscuits etc. etc. Its the interaction with the crowds that keeps one going. You make eye contact with people you don't know, you've never seen before, but who are there willing you on to the finish. When these strangers shout " come on 440(my bib # at Mumbai), you are doing great, dont give up" there's a contact that lifts one through exhaustion. It's as if the crowds don't just watch - they're part of the race. They are close enough to touch as you pass and the children love to slap hands and high-fice with the runners. The effect of all this on a runner can be very positive - crowd support and interaction is one big factor which contributes to my enjoyment of the Mumbai marathon every year!