Tiagra 4600 and brake issue
I am currently rebuilding a 15 year old road bike for my daughter, but am having trouble with the rear brake. It came standard with Tiagra 4600 levers and Tektro r312 brake calipers. When we got the bike, the rear brake didn’t have a lot of stopping power, so I tried a bunch of different things to fix it. I changed the cable and outer sheath, the pads, cleaned the calipers, lubed the levers and adjusted everything. It still didn’t work well, so I swapped in some other calipers I had spare, and that made no difference. The brake just has no feel or power. I can’t imagine it is the lever, but that seems like the only thing I have left to change! What am I missing??