Rear derailer and flat tire repair

In a recent lucky turn of events, my mountain bike tire popped while on a bike trail and, on my way to the bike store for supplies with my girlfriends bike, her rear derailleur broke. What’s a guy to do?

The bike store wanted me to leave the bike there for 4 days and pay for the parts and labour to fix it. No can do. Wanting to be a master of my stuff and improve my skills, I just bought the parts and figured I could do the labour myself. I know fuck all about bikes, but I have a knack for being able to type things into google like “How to repair rear derailleur” and getting millions of results telling me how to do it.

So, I picked up a Shimano Alivio Rear Derailleur for $50, a set of tire levers for $6, 3 new tubes, and a mini pump for $25 (I plan to travel with the pump, the levers, and spare tube in the future).

I tackled the popped tire first, under the correct assumption that it would be easier. Using my masterful intelligence, I successfully browsed to, typed in “How to fix flat bike tire” and voila. I followed this video and had my tire back on my bike in no time:

The rear derailer was a bit trickier. The one on the bike was bent pretty bad. I took it off with my trusty allen keys. To attach the new derailer chain and all, there are two popular methods. One is to break the chain and then feed it through the attached derailer. I didn’t have a tool to break my chain, so I couldn’t do this. The other is to take derailer cage apart in half, put the chain in place (you don’t need to break it, I recommend looking at a functioning bike), and reattach the cage again. All the physical work I needed to do was turn some allen keys. Anyone can do it! Now simply put the cable back through the derailer, and voila! The bike should function, but the shifting is probably off. From here, adjust the cable tension so that what you see on the handlebar shifter is properly correlated with the cog the chain is on, and use the adjustment screws to tune the upper and lower movement limits of the cage. Rather than give it much more explanation, I will send you to this fantastic resource I used from Shelden Brown
as well as this video on adjusting the indexing:

Fixing these bikes was satisfying [and fun!] and I will continue to do everything myself. Eventually I want to be able to build my own bike from the components. For now, I will learn to tune up these bikes to mechanical perfection and fix anything that comes up 🙂