I took the bike trip with five of my friends. Two of the guys had some riding experience before the trip. The other four learned from the guide for all practical purposes. Basically, the riding is pretty easy and the guide mades sure he takes you only to the places that you can handle.
The real joy off the trip is really not the bike riding, but the places you get to see and the people you meet. We took the North trip from Hanoi towards the Chinese border. Along the way we stayed at local hotels (fairly clean and comfortable) ate with the locals (unbelievably good food, no exaggeration here) and got to interact with a whole host of Vietnamese people as well as ethnic minorities that live on the mountains.
It was a phenomenal experience! We met and stayed with Zao people that have never seen a Westerner before. In a couple of the places we stopped, children would rush to me, and pull my beard to make sure it was real! And, stuff like this is a daily experience. Northern Vietnam is one of the last virgin spots on earth, and I cannot imagine a better way of seeing it. Really, if you can afford it, go there and ride through the country with a Minsk. And make sure you do it with this company, as riding with these boys and watching them interact with the locals makes half the trip.
Now two words of caution:
(1) the guides take you to the best hotels and restaurants they can find. But, you are on top of the mountains, and while the hotels and houses you stay in are always clean, the same cannot be said about the restaurants. Half of our group got extremely serious food poisoning (dysentery), while the other half was perfectly OK. (I even gained some weight.) So, make sure you have your shots, and take some Cipro with you. (BTW: Malaria pills are totally unnecessary.)
(2) Northern Vietnamese drink a local brew called Zeal. I think it translates roughly to “Gasoline” in the West. The Vietnamese are fantastically friendly people, and wherever you go, they want you to drink with them. Getting foreigners drunk and happy is their way of showing hospitality. And despite their small size, they can all drink like devils. It is extremely rude to decline a drink and just about every random Vietnamese that spots you wants to be hospitable to you. Therefore, every night after your ride, you should be prepared to party heavily with the locals. For me, this was one of the greatest parts of the experience. I can see, though, how this can take a toll on other groups.
In conclusion, this is was the trip of a lifetime. I have seen things that I did not even know existed, and met people I never thought I would. It is a comfortable ride administered by super guides. Again, if you can afford it, do it.