I've been using and abusing my Omnium Cargo for 2 years now and this is my review
Is the Omnium Cargo difficult to ride ?
In my own experience, it took me only a couple of minutes to get basics riding skills, you can get use to it fairly quickly. For the fine tuning it takes a bit longer though. These are the three things I would pay attention to:
The front of the bike is longer than normal: (thanks Mister Obvious !) when you turn to avoid an obstacle the front of the bike is going to follow a curved trajectory, which is hard to anticipate at the beginning but you'll get quickly the hang of it.
The front wheel is very small: Small wheels get caught more easily in big holes or in tram tracks. Even with wide tires (mine are 47mm) I always pay special attention when I'm crossing over tram tracks, do it as perpendicular as you can.
No no-hands: The front wheel is very reactive. This is normal because the bike is meant to be loaded at the front and the extra weight creates more steering resistance, so when the bike is not loaded the steering is very sensitive, too sensitive for no-hands. And when the bike is loaded I wouldn't dare a no-hands either... so no no-hands on the Omnium Cargo !
How does the weight affect the ride ?
The bicycle feels very stable when it's loaded, I would say even more than when it is unloaded. Let's see that in detail:
The steering: As mentioned before the steering is very sensitive when the bike is unloaded but as soon as you put some front weight on the steering becomes normal.
Load's hight: On the Omnium Cargo the platform is above the wheel, which helps to keep a compact design. As a consequence, the center of gravity is slightly higher than other cargo bikes. I think the difference is not huge, the Omnium is a very stable bike in my opinion, loaded and unloaded.
A potential down side of having a relatively high platform is that, if the load is too close to the handlebar it could get in its range of movement. That is certainly a limitation for big volumes. It's never been a real problem for me, only one thing to consider when I'm organizing the load on the bike.
Compliance: When the bike is loaded, the front becomes very compliant, the elastic properties of the steel frame shine. The bicycle feels extremely comfortable and supple at the front end which facilitates control. The back end of the bike keeps its normal rigidity.
Is it as light as they say ?
The bike is as heavy as a touring bike, which is impressive for a cargo bike. I can relatively easily put the bike on my shoulder and take it downstairs to the cellar when I need to, I wouldn't do that every day but once in a while is fine.
According to the manufacturer the complete bike weights about 18 kg but my build weighs about 22kg.
The size and fit
The Omnium Cargo is currently sold on only one size: M. On their website they say it fits riders between 170cm and 190cm.
I'm 183cm tall and I put a 80cm stem on. I fit fine but I think a taller rider could fit slightly tight. On the small rider's side, my girlfriend is 165cm tall and fits fine on the bike when we put the seat at her hight. If we changed the stem for a shorter 70 or 60 cm she would fit perfectly.
What can the Cargo take on ?
Here there are some examples of what I'm able to carry on the Omnium Cargo without the extensions. I've never used the extension, the rack is plenty large for my needs: