To be honest, it's not the best time to go cycling in mid summer. I'm sure you're aware of that, so if you're going in the near future, within a couple of months, I'd suggest only hill stations in the northern most parts (can't stray south and have a tourist ride around this time, not in the 40C heat and humidity anyway). Sikkim is a very good place to ride at this time of the year, but safety will be a bit of an issue on those winding highways. Manali's definitely the safest bet for a decent route. Though riding 500km all the way to Leh at altitude will be proper taxing. As Zam says, MTB bike, don't want to test out the stress failures of expensive road bikes.
Another suggestion, a rather obvious one, would be to avoid urban India as far as possible. The roads are too busy for bike tourism.
Riding in India isn't suicidal by any means, not if the eyes and ears are on the road and not the Ipod.