  We report electrical and thermal transport properties of single crystalline
kagome metals $A$Ti$_3$Bi$_5$ ($A$ = Rb, Cs). Different from the structural
similar kagome superconductors $A$V$_3$Sb$_5$, no charge density wave
instabilities are found in $A$Ti$_3$Bi$_5$. At low temperatures below 5 K,
signatures of superconductivity appear in $A$Ti$_3$Bi$_5$ as seen in
magnetization measurements. However, bulk superconductivity is not evidenced by
specific heat results. Similar to $A$V$_3$Sb$_5$, $A$Ti$_3$Bi$_5$ show
nonlinear magnetic field dependence of the Hall effect below about 70 K,
pointing to a multiband nature. Unlike $A$V$_3$Sb$_5$ in which phonons and
electron-phonon coupling play important roles in thermal transport, the thermal
conductivity in $A$Ti$_3$Bi$_5$ is dominated by electronic contributions.
Moreover, our calculated electronic structure suggests that van Hove
singularities are sitting well above the Fermi energy. Compared with
$A$V$_3$Sb$_5$, the absence of charge orders in $A$Ti$_3$Bi$_5$ is closely
associated with minor contributions from electron-phonon coupling and/or van
Hove singularities.
