I am doing the same trip in July & a friend of mine did it last year & the following is part of an email he sent me......I intend to use them as well
And they are in Chandigarh !!!!
We went independently with no tour leader and had no major problems finding food, accommodation, etc. Rajiv gave us some contacts and we had the lonely planet guide or we just cased out the area and found the best looking place. We hired a GPS from Rajiv with local maps which also helped us out especially when you are coming into a city and need directions to the hotel. We also hired a tent and sleeping bags for emergency use if we got stuck on the road as it gets very cold in the mountains at night but we didn't need them. I estimate it cost me about $3500 for the airfares, bike hire , food , accommodation, petrol, etc with 3 of us going and sharing accommodation costs. This is about one third the cost of some well known tour companies although you can find cheaper ones in India. We met some riders whos bikes were older and hired from Manali. Their bikes had "died" and they had to complete their trip by bus. I would go with Royal India Bikes
as they only use late model bikes and turn them over frequently ( ours had done about 10,000kms)