I booked a day trip for 8 lads from Hoi An to Hue with Easy Riders and we all had a fantastic time. There are a few different companies using the Easy Rider name but this one is legit, check their website (www.vietnameasyrider.com) for detail on their tours.
We were collected on large bikes, plenty of room for our luggage to be strapped to the back and still be comfortable as a passenger. I'm 6ft4 and still had lots of space so don't worry about that!
The drivers were all great, up for having a laugh with us at times but when it came to their driving they were very careful and alert. I felt completely comfortable as a passenger.
Our tour guide (and my driver) Mr Quang was excellent. He is so friendly and full of interesting facts about the area. He also speaks very good English.
We stopped at a local restaurant, which Mr Quang recommended. The food was delicious and very cheap, it also helped that the menu was in English. When we left he took the meal bill, as he said he wanted to make sure his customers were not being overcharged, and so he only returns to restaurants in future if they keep their prices down. Seriously this guy is brilliant!
Now onto the actual tour. We travelled over Hai Van Pass, which was simply stunning. Don't go to Hoi An or DaNang without spending a day on bikes around this place, it was so picturesque. As they said on top gear, this is one of the best coastal roads in the world, I can second that, it would take some beating!
This is a new trip advisor page, as all the copy companies have got reviews from the wrong passengers but to make sure you get the right one, email River (firstname.lastname@example.org) to arrange your bookings. He was fantastic with me and customised the trip based on what I needed. Seriously, I can't recommend these guys enough. I live in Saigon and will definitely be using them again!