score:4
As you are no "serious bikers" I would bot buy any equipment right now. You have interesting options for bike rentals:
Within Brussels, you can profit from the Villo network, a bicycle sharing system.
For trips outside Brussels you can take advantage of the "Train + Vรฉlo de location" offer by the national railway company (SNCB/NMBS). Note that there does not seem to ba an English version of this page. Go to a "manned" train station of your choice and ask for details. With this scheme you buy a train ticket to a destination of your choice and you will get a rental bike at that destination. As an example: A trip for two adults to Ghent is 31.40 EUR. This includes a return ticket from Brussels to Ghent and the rental of two bikes for one day.
I have cited Ghent as an example. It is a good choice for a first trip. There are plenty of destinations available. Anyway, if you want something "easy", pick a destination in Flanders.
If ever you decide to buy a bike when living in Brussels, make sure that you have a safe place to park it.
Upvote:5
A good way to get started is have a weekend based in Bruges, and do a couple of relaxed day trips from there. There are several bike rental places in town, and you can do long or short day trips as you please to get comfortable. A nice one to get started is to head East along the canal towards Sluis, which is just over the border into the Netherlands, only about 15km.
Flanders, the northern part of Belgium, has an excellent cycle network that's very well signposted, and perfect for leisurely day-trips. You can buy special maps that have all cycle routes on them, and all intersections are numbered, so you can create a route just by listing all the numbers you need to go through, and then as you are cycling, keep an eye out for the numbered signposts along the way. The Fietsroute.org site has information about this. You may be able to get these maps at the Flanders Tourism office that's just around the corner from the Grand Place in Brussels, so you can do some planning in advance.
There's also good cycling to be had in Wallonia, the southern part of Belgium, but it's less beginner-friendly; it seems to be more oriented towards long-distance cycle routes, so it's not as easy to navigate as the Flanders cycle network.