The Expert Columbia you see in the pictures was sold at the Copake auction in 2012. This 54 inch bicycle with serial number 12598 shows the final version of the 'Expert'.
This bike has the square fork crown, used in the years 1887-1892.
It has the spade grips, that were standard from 1889. The old model remained an option. I think the woorden grips are not original.
It has the correct 'fourth pattern' Kirkpatrick saddle, used in 1890-1892.
It's a pity the step is not original: in the years 1888-1892 the Expert was fitted withh an adjustable step. The fixed step on this bike was never used on Columbias.