There are a number of websites listed below with pre-prepared .map files you can download for various parts of the world. Just get the unziped file onto the sd card then use the option in settings -> Audio Visual settings -> Map settings -> MapsForge file to tell IpBike which file to use. Then in the map double tap for the menu and choose tile source and select MapsForge.
openandromaps These are good with contours well worth making a donation.
download.mapsforge.org The official mapsforge source.
openmaps.eu I have not tried these (no UK..)
extract.bbbike.org Lets you select a custom area in case your on a join for other sources.
Do it yourself Instructions for preparing your own .map file. It is non trivial though.
You can change the rendering theme with MapsForge if you decide to do this be aware that IpBike is using mapsForge 3.0 not the newer versions with .svg file support.
Ipbike uses the osmdroid mapping library which will allow you to read map data from files on the sd card. The easiest way to prepare these files is to use the java application Mobile Atlas Creator to make map files of the area you want on a pc then transfer them to the appropriate directory on your phones sd card for IpBike to use them. These are instructions to guide you though the process, I will assume windows but it should be similar for most things for other operating systems
Mobile Atlas Creator needs to be installed on a pc. There is a download link for the latest version on the home page, as of writing this it is version 1.9.7 You will need a Java run-time but most people will already have a suitable one.
You need to unzip the downloaded file to where you want it installed.
To start mobile atlas creator double click the Mobile Atlas Creator.exe. The first time you start it you need to select the atlas format there are 3 Osmdroid options zip, GEMF and SQLite I recommend the GEMF format especially if you want to do a big atlas as it is far quicker to load on the device and the size is similar for all the options. You can reset this selection and start a new atlas with the atlas - new atlas menu option. You need to select the map source to match one of those supported by IpBike this is the second option on the left hand panel. The compatible options are OpenStreetMap Mapnik and OpenStreetMap Public Transport. 4uMaps (in europ only) and MapQuest.
You can zoom drag the main map with a right click. You can zoom in and out with the mouse wheel or the control at the top left. The grid view lets you select the grid size I normally set it to the most zoomed in level I want tiles for e.g. typically 13-15, or the most zoomed out level.
You select the area you want by left clicking and dragging out a rectangular box. There are other options check the maps - selection mode menu. Having selected an area you need to choose the zoom levels you are interested in. In the left Panel there is a zoom levels section with a tick box for the levels. The total number of tiles is displayed at the bottom of the zoom levels selection box. You should not have the higher zoom levels unless you really need them as the tile count gets up a lot. If you zoom the map into the same level you are interested in you can see if the detail is OK or whether you need to zoom in some more or can zoom out a level or two.
Once happy with the zoom levels and the selection go Add selection to add the selection to the map, you can add multiple selections to the same map. The name section lets you set the name before you press add selection.
Once you have the areas added to the map press Create Atlas to start the atlas creation prosses, this can take a bit of time as the tiles are downloaded.
Once done you will have directory under the atlases directory for your map in this there will be a .gemf file. You need to copy this to the phones sd card into the osmdroid directory. As the file is probably relatively large it's probably best to plug the phone in with the usb cable and use that for the transfer.
There is nothing to be done with IpBike to use the file apart from selecting the appropriate map format from the choose tile source map menu (double tap the map), it should be picked up automatically as will multiple file if you put them in the osmdroid directory. The best way to do a quick test is to switch the data connection off and pan the route map around the area a bit to check you get the tiles OK.