Diffusion MRI is sensitive to heterogeneity tissue microstructure. Recent methods for axon diameter estimation rely on diffusion MRI data acquired using advanced scanners with b-values higher than 6000 s/mm2 so that signals from extra-axonal components vanish because of the underlying relative high diffusivity. In this work, we introduce a method for axon diameter estimation that uses diffusion MRI with two TEs and relative lower b-values acquired using clinical scanners. Our method separates signals from intra- and extra-axonal components by exploiting the b-value-dependent relaxation coefficients. The performance of the proposed method is demonstrated using in vivo data acquired from a clinical scanner.