This is probably a very specific project, but it’s one that I was doing for myself anyway and I happened to take pictures.
What is this and why did you do it?
This is my bike, a 2014 Giant Defy 3, and for whatever reason ever since I bought it the front derailleur (the thing that changes the gears) has had alignment issues leading to it rubbing which makes dumb noises and is inefficient. I’ve fiddled with it myself a bunch, I took it back to the shop enough times for them to roll their eyes (that’s once, in my books) and in the end I realized I’d really never used it in the last 4000+ km of riding, so I could probably safely just get rid of it altogether. There’s a very minor weight savings, but it also cleans up the look of things if you like the more minimalist fixie style without sacrificing the gears on the back.
Things you’ll need:
Basically just hex Allen keys in both metric and american sizes, Greek yogurt (lemon Liberte is my favourite, you can use whatever you like) and I just had some chain lube because I’m going to do a nice scrub and clean afterwards. Optional tools that might be handy: pliers (regular and needlenose), a flathead screwdriver and duct tape. Also, if your chain doesn’t have a Sram Powerlink style coupling, you’ll probably want a chain break tool.
My bike has two gears on the front (also called chainrings) and I’m planning on getting rid of the smaller one. It’s pretty easy, there’s these five silver fasteners that are sort of like hollow Chicago screws and they just screw off with the hex key (mine were american sized, yours might be different). They might snap a little as they get unseized, that’s fine. Also, you need to make sure the back half isn’t rotating with the front half as you screw – mine had little slots for a flat screwdriver but I found it just as easy to use my finger to apply that friction.
Now, watch out! Your rear derailleur is designed to keep the chain in tension so you might (and I did) have the chainring slip off the crank (the pedal piece) and shoot backwards. Not so much dangerous as surprising but still, be warned. This is where I got a bit crafty: using tape of any kind, you can bring that tensioning arm up and tape it to the chainstays (that back triangle arm of the bike frame) but make sure the chain itself can still rotate freely. This’ll keep you from having to hold against the tension yourself all the time. Nice!
You can now remove the chainrings by slipping them over the crank and re-install those five screws again. I don’t know if there’s a specific torque to screw them to, but the force transfer through the crank is going in sheer through that back half of the Chicago so the front is really just there to keep it held in. As such, I really don’t think it matters, as long as they aren’t going to unscrew themselves easily. Again, flat screwdriver on the back can help you here as you hex key the front.
Now for the derailleur mechanism itself. There’s two flathead screws holding it to the frame so grab a hex key again (mine were metric) and undo those. Another hex key to release the tension cable and you should be able to pull the whole mechanism free.
“But wait” you complain “it’s trapped on the chain because of that closed silver loop” and you’re right. We’re going to have to undo the chain to free it.
Conveniently, my chain has one special link with little slots in it. This is pretty common, I think, on modern bikes so pedal yours around the full loop and see if you have one (the slot might be filled with greasy gunk as mine was, hiding it). If so, use some pliers to decouple it, if not you can use a chain break tool (or any sort of vice + small metal pin) OR, if you’re feeling destructive and don’t want the derailleur itself anymore, you can just cut the silver part with heavy snips and mangle it until it’s free. This was actually my approach until I happened to learn that my chain has that much easier unlinking option. With the chain back together, you can take the tape off the tension arm and give ‘er a whirl. Everything should be back together and working at this point.
With the derailleur itself gone, all we’ve got to do is remove the cable. Bikes have a variety of cabling methods, but mine had a clamp on the underside and it leads all the way up to the handlebars. Your bike might have grip shift (where you rotate a bit in the handlebar to change gear), trigger shift (which is similar but with clicky triggers) or the road bike integrated brake style like mine here.
There’s a little metal ball on the end of the cable that holds it into a knuckle on the inside of the shift mechanism. I just pushed the cable from the other side and used some needlenose pliers to fish it out. You can either cut the end off or pull the entire cable through (note, you might have to hold the shift lever to the side to let the grabbing mechanism relax and allow cable travel). Remove any of the black tubing bits and you should be done!
Now, for the most important bit. Remember that lemon yogurt we had? Wash your greasy hands and sit back, relax and enjoy!