Level of Importance for a longish distance commuter IMO goes as follows:

Fit/Comfort, suitability as a commuter (racks/fenders/wide tires/etc, for those that want them) fit/comfort, efficiency, frame material, styling (is it cool, yo?)

Hand numbness can be rough roads, skinny or over inflated tires, bars too low, or lack of quality grips (ergon grips are amazing,) or a couple of other reasons.


It sounds like your bike is ideal. Throwing a lot of money at a comfortable bike in hopes of being noticeably faster will likely result in disappointment. Only major change would be a more aero position, that'd really help if you keep above 12mph. Lighter tires/rims would feel quicker, and make the most difference next too aerodynamics IMO. Overall bike weight when you take rider weight into consideration is a small part.

After looking at your bike, a new quill (stem,) some drop bars, bar end shifters, bar tape, and brake levers (v-brake compatible or regular f you switch too cantilever brakes) would make that a drop bar bike. Sounds like you're wanting new brakes anyway, and a good set of canti's once setup correctly are great.

If you're still using those slime tubes, lose them for a much quicker feeling ride. I'd vote going that route and seeing how it works for you.