  We study invariant Einstein metrics on the Stiefel manifold
$V_k\mathbb{R}^n\cong \mathrm{SO}(n)/\mathrm{SO}(n-k)$ of all orthonormal
$k$-frames in $\mathbb{R}^n$. The isotropy representation of this homogeneous
space contains equivalent summands, so a complete description of $G$-invariant
metrics is not easy. In this paper we view the manifold $V_{2p}\mathbb{R}^n$ as
total space over a classical generalized flag manifolds with two isotropy
summands and prove for $2\le p\le \frac25 n-1$ it admits at least four
invariant Einstein metrics determined by $\mathrm{Ad}(\mathrm{U}(p) \times
\mathrm{SO}(n-2p))$-invariant scalar products. Two of the metrics are Jensen's
metrics and the other two are new Einstein metrics.
