Can I Replace My Existing Brake Levers With Aluminum Ones?

Aluminum bicycle brake lever

You can replace the brake levers on your bike with a lighter and more ergonomic model. These models also tend to be more durable, particularly in the case of forged aluminum levers.
If your existing brake levers have a soft or spongy feel, it's likely air in the system that's preventing power from being transferred efficiently between the brake lever and the caliper. A brake bleed should solve this issue.

The most common solution is to swap out the existing brake and shift cables with a thinner version. However, this can lead to less reliable operation as thin gear cables are more sensitive to contamination and dirt than brake cables.

To remove the old cable, back off the barrel adjusters (turn the adjustment bolts clockwise) on both calipers and undo the cable retention bolt on the levers. With slack in the cable, pull the brake lever so the end of the inner can 'escape' from its hinged slot within the lever assembly and then feed the new cable through the outer. On flat-bar levers, this may require a screwdriver to help loosen the end of the cable from its mount within the lever assembly.