I had the same thing happen when I replaced a rear tire. Check the alignment of the brake caliper, there is a rubber pad on the forward part of the caliper that hooks the frame. If that rubber pad is not on correctly it will throw off the alignment of the caliper. I did a short ride just to check my rear tire and my rear brake was hot and you could smell it. Any longer ride and they say the brakes can fade because you are cooking the fluid in the caliper. Just something else to check, you wouldn't think it would make that big of difference but it does.