possibly depends on how you hold you head while riding more upright is better for the body. when you are "down on the drops" your head is hanging out in front of your body and your neck has to support the weight and the added weight of the light could be making a difference. I had been trying to do more push ups this year to strengthen neck/ upper back muscles to decrease the soreness I sometimes get with riding a lot.


it could also be the way you slept too.