Just like Lazychubs said, If there is an incorrect size spacer between the bearings (Too short) then it will make the bearings tight and hamper their performance. One thing I always do when installing sealed bearing 3 piece cranks is to put the cranks together outside the frame then put them up against the bottom bracket. If the flanges on the bearing cups sit on the outer edge of the bottom bracket of the frame then the correct spacer is what you have so you can go and install the cranks. Otherwise you will need to put an extra spacer washer in. You will know what to do after a very short period of time. I had the same problem the first time I ever installed sealed 3 piece cranks.
