Hi,
You can cycle independantly and safely in the Bale NP, but the only part which is suitable is the Dodola-Dinsho-Goba-Sanetti Plateau road. The tracks inside the NP are absolutely not suitable
.
Don't miss the Sanetti Plateau, one of the most impressive place in Ethiopia, In 2003 we cycled there to the top of Mt Batu (Tulu Dimtu) at 4377m. Great moment!
For Bale NP maps look in the Bradt "Ethiopia" handbook or ask the Ethiopian Mapping Authority [http://www.telecom.net.et/~ema/] and then go to their office once in Addis. I got very accurate 1:25'000 map of the area directly from them for a fiew ETB.
Details and photos from our MTB tour in 2003: look at "AbyssiRaid 2003" on my website [http://farenj.alpavista.ch/index.htm].
PM directly if you want more advices and details.
Regards,
Farenj