just got a giant tcr comp limited in a medium and i sometimes feel like im too small for the bike. I am 5'7 and wear a 30 in pants. 17 in from pit to wrist. Not sure how to measure torso. I feel so stretched out, i know its a race frame but still. Didnt feel to bad on the test ride and the guy said i looked good on the bike. Do i need the small or do i just need to make some adjustments. I got this pain in my upper arm area, just above the bicep and between my tricep. Does my body just need to get accustomed?