Early brake-levers didn't have a return-spring and this required a stronger spring in the brake-caliper to pull through the cable and pull back the lever. Newer levers have a return-spring and only needed a light spring in the caliper. Both designs of course, assumes that your brake-cable is well lubricated.
In the OP's case, he might have the worse combination possible, light-action calipers with no-return springs in the lever and rusted cables..
Here's a test, unbolt the brake-cable from the caliper and remove completely. Squeeze the brake-caliper by hand so that both pads touch the rim, then let go. Does the brake-caliper open back by themselves? If they do, nothing is wrong with the brake and the problem is there's excess friction in the cable or the brake-lever.
Nessim's advice is the best:
1. take apart the brake-caliper and grease the pivots and lightly oil the spot where the arms rub on the return-spring. Some brakes have a lock-nut/adjustable-nut combination on the pivot-bolt. Make sure you adjust it tight enough so there's no play, but not too tight that it binds and the brake can't re-open by the sping. Then tighten down the lock-nut.
2. fully lube the cable. Pull out the inner cable completely from the housing and spray some teflon-lube down the housing. Re-insert the inner cable. If you prefer not to remove the inner-cable due to frayed ends, drip lube down one end and pull the cable back and forth until the lube shows up at the other end. Only then can you be sure the lube made it all the way through the housing.
3. lube the pivots at the brake-lever. Most levers use plastic bushings in the pivot of the lever and the body. If the bushings are worn, you may metal-on-metal contact and a lot more friction. Replace the bushings if necessary.
Last edited by DannoXYZ; 08-02-08 at 03:57 PM.