It might be contestable if you don’t mind a bit of extra effort plus a court appearance. Bellevue gives out a lot of the “inattention” tickets probably with the idea that most people are more likely just to pay and not contest. The Seattle Times has an informative article about those tickets relating to many King County jurisdictions. The good thing to know is that “inattention" ordinances are local, will not go on your state record, and do not have any effect on your insurance rates.
If you would like to try contesting you will need to examine the sworn statement filed by the officer with the court, and look at how he measured your speed. If you have not already, read the sticky thread Procedural Guide to Traffic Tickets in Washington State, which links a discovery template. You can use that template to file for discovery which will include the officer’s statement. Forum members can help you decipher the statement. To do that you will need to redact anything that identifies you (including the citation number), upload a digital photo or scan to an image sharing site and link the images here in your thread.

