Actually Washington introduced riflemen along with the initial formation of the Continental Army. Pikes were also recommended for use in the rifle regiments. A folding Pike was to be introduced, manufactured, and issued to the rifle regiments. This folding version didn't really appear.
Aug.26th, 1775
..., the Use of Pikes in one or two Rear Ranks is recommended to the Attention and Consideration of our [rifle] Battalions. Every Smith can make these, and therefore the Country may soon be supply’d with Plenty of them. Marshal Saxe’s Direction is, that the Staff be 14 feet in Length, and the Spear 18 Inches, thin and light; The Staff to be made of Pine, hollowed for the sake of lightness, and yet to retain a degree of Stiffness; the whole to weigh not more than 7 or 8 pounds. ..., The Committee of Safety will supply Samples, to those Battalions who are dispos’d to use them. Each Pikeman to have a cutting Sword, and where it can be procur’d, a Pistol....
After two years, the riflemen were removed from the main army and sent to the Western Department, while the Continental Army, now devoid of rifles, faced the British Army regulars.
The British during the first years of the war, to save money AND because it was unnecessary, would perform bayonet charges without prior musket fire. (see With Zeal and Bayonets Only by Matthew Spring). When the army eventually corrected its lack of having bayonets, AND coupled that with Von Steuben's retraining of the army, THEN the Continentals were able to go toe-to-toe with the British regulars, and the war became a war of attrition.
LD