Coming from many years in a Business dress environment I think you'll find that the cut and materials of dress pants are as suitable to cycle commuting as wearing the suit-coat and tie that completes the wardrobe: hardly at all. A decent suit with the traditional two pair of pants will last through years of wear in it's intended environment with regular dry cleaning. Worn on the bike the crotch will quickly wear through on the trousers, the inevitable chain grease and snag will ruin them and replacement will be costly. The point of traditional business dress is to present a professional appearance to your associates, customers and partners. Worn, soiled or smelly doesn't exactly meet that requirement. The dress code is important to your employer or it would't exist, respecting it shows respect for the job.

Re-think changing from/to commuting kit to office wear daily.
Ask your supervisor about proper parking for your machine, where to clean-up and change and where to store your dress garb in off-hours.
Such accommodations are common today and should be worked out straight off.

Good luck on the new job.

-Bandera