Bicycle touring offers a chance to explore the island alongside the Cubans themselves. Roads are little trafficked yet full of hazards. Wear a helmet! Most airlines treat bicycles as a piece of luggage and require that bicycles be boxed; Cubana does not. Bring essential spares, plus locks.
If planning an all-Cuba trip, touring is best done in a westerly direction to take advantage of prevailing winds. A good resource is Bicycling Cuba, by Barbara and Wally Smith.
In Cuba, Havanatur (tel. 07/201-9763, www.havanatur.cu/cicloturismo.asp [1]), Cubanacán (tel. 07/208-9920, www.cubanacanviajes.cu [2]), and WowCuba (Centro de Negocios Kohly, Calle 34 e/ 49 y 49A, Kohly, Havana, tel. 07/272-1777, www.wowcuba.com [3]) offer bicycle tours.
Links:
[1] http://www.havanatur.cu/cicloturismo.asp
[2] http://www.cubanacanviajes.cu
[3] http://www.wowcuba.com