I'm a newbie 'wrench' , trying to fix up an ~10-15 year old road bike (has Bridgestone decal on downtube but Schwinn sticker on the head tube). The bike has Shimano 600 components all over. The STI shifter cable for rear cogs broke/wore out and have to replace it. Should I replace all shift cable housing or can I reuse it? Also, do you recommend replacing the shift cable for the front chainwheel at the same time? Thanks in advance for your suggestions.