I have an old Haro mountain bike I love. One feature request I have for a new bike is disk brakes. Is it possible to install disk brakes on an old bike? Is it worth it?
It isn't wise to install disc brakes on a frame and fork that weren't designed to withstand the unique forces that disc brakes generate, and you'll just damage your bike in the process.
If your Haro does have disc brake mount tabs, then you can install them but likely only with smaller disc rotors. Remember that you'll have to get new wheels too, which increases your total cost.
Disc brakes are great for many riders, but then again so are rim brakes. Do you really need to switch?
Whatever you do, don't attempt to install disk brakes on a bike that wasn't wasn't built for that.
Even if your frame supports disc brakes, I'm guessing it wouldn't be cost effective: You'd need new hubs, the brakes themselves, and possibly new brake levers and shifters.
But yes, disc brakes perform beautifully regardless of the weather.
Is it worth it? Hell yeah. Especially for wet or muddy conditions.
Is it possible on your bike? Probably not. Unless you get new wheels, a new frame and a new fork. In which case you might as well buy a new bike.