Originally Posted by
Erik_A
I don't know anything about the Alex rims except to say that 19mm width and 23mm width are different off road. The behavior of the tire at lower pressures would be the determining factor for me.
The mountain bike hub is 135mm wide versus the 130mm width of the road hub, therefore they will not fit the spacing on your cross bike. If you want cheaper than 105, then you're better off with one of the "numbered" varieties offered by Shimano or just purchasing an a23 wheelset from a builder.
However, that's just my opinion. Take it or leave it.