Check that the chain isn't dragging on something by backpedaling. Next, lift the bike and check that both wheels spin freely and aren't touching the brake shoes for instance. If both tests are negative it's probably in your head. I don't know where you live but it's been hot in New York and that makes everything seem harder.
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An ounce of diagnosis is worth a pound of cure.
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“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.