Hi Aubrey,

Isn't it fun how infectious and exhilirating this is?

Here are my thoughts on your questions:

-shoulder/neck muscle soreness: are you locking your elbows, especially after 15+ miles as you get tired? If you do that, you drive the pressure of keeping your body upright into your hands and your trapezius muscles. Try to ride with your body bent at the waist so that your elbows are not locked and you're looking down directly onto the hub of your front wheel. And that's the second part of the story: are you sitting forward enough, or are you so stretched out that you have to lock your elbows to keep your saddle position? Try adjusting your saddle forward so that you can just see the hub of your wheel below your handlebars, and if the bike fits you, that saddle position will be just right to have your knee over your ankle when your feet are on the pedals at halfway around the pedal circle.

-saddle soreness: do you mean sit-bone soreness or muscle soreness in the general glute area? Sit-bone soreness can mean either you need to build up endurance and get used to it or you need to find a saddle that better agrees with you. If it's muscle soreness, I recommend stretches that concentrate on the glutes and the piriformis muscle, such as the yoga pose pigeon and the stretch where you cross your ankle over your knee and bend over it.

Hope that helps!