If you check my route map on my website (
Take On Africa: A Journey by Bike from UK to Cape Town), I passed this region in december / january last year.
From Banjul to Bissau the road is all tarmac'd and in good condition
I did not take the main road from Bissau to the Guinea border (through Gabu) so cannot really comment on that. I did cycle along about 15km of it east of Gabu - it is tarmac but very badly pot-holed.
I think further on it may be earth road. From Bissau to Gabu I understand the tarmac is in much better condition. If you ask Peter Gostelow (
www.bigafricacycle.com) I think he recently took this route and can tell you about the road in northern Guinea.
I know that the road from Labe south is tarmac and good condition. You could take this road all the way to Conakry and would be tarmac.
From Conakry south to Freetown I do not know (I took a different route unsuitable for a 2wheel drive or indeed anything other than a motorbike or cycle) but suspect it is also tarmac.
It will be the dry season and I think the earth road in northern part of guinea would be passable in a 2wheel drive but don't quote me on that. In parts, even though the tracks are hard and driveable then can be quite rutted depending on when they were last smoothed.
Safety and security was no problem for me. Keep abreast of current politics though, but generally these things only flare up in the capital. I avoided Conakry for this reason as it was shortly after the assassination attempt on the president. The rest of the country was unaffected although I heard rumours of rebels in the area....
The people in the Guineas are very kind and helpful and I never had any hassle (except from the military at the Guinea border; the military are another matter).
There was a heavy military presence in the Casamance region of Senegal, but they were just patrolling and left me in peace most of the time, only engaging to check I was ok. Again, check up on current security situation.