Reddit reviews SHIMANO SGS Top Normal Shadow Rear Derailleur

my bike is a rehabbed 99 GT XCR-4000. here's a brief summary of my current configuration, with costs & reason for replacement. I should note that I wanted to buy a cheap bike to get into the sport and learn how to do maintenance so if I got a nice bike I wouldn't be actively destroying it. I've had the bike for a few years now and replaced a bunch of things. anyways, this is roughly in the order that I replaced things.

Stock: Frame (duh), seat tube, head set / stem.

new:

Shifters: Shimano Alivio 3x9. the shifters were shot when I bought the bike, had a set of microshift ones that lasted a year but sucked and broke. $65 for the pair

Drivetrain: new chainrings $10-$30 each, cassette $35, chain $22, Front Derailleur $20, rear derailleur $68. The drive train was such a mess when I got the bike, I've destroyed some good components from being a noob. all straight now though. kept the 3x9 arrangement since the sifting wasn't holding back my riding at the time.

Fork: Rockshox recon silver solo air $200 the 15 year old rockshox judy was sticky, heavy (coils) and the only damping was the stiction of the tubes. Super happy with the replacement, it's steel so not super light but the adjustable rebound damping made a huge difference. when I bought it they had rim brake mounts as an option on the amazon page, not sure if that's still available. the rim brake version that I have does have disk mounts as well.

Wheels - $100 craigslist. the stock wheels were a mess and impossible to true well - I broke a spoke on my rear wheel which then got sucked into my RD, destroying that and breaking another couple spokes in the process. decided to say screw these old things and bought a new set of wheels, this time with disk brake hubs - thankfully my frame had mounts for the rear.

Disk brakes: avid bb-7 - $60 ebay(new). purchased at the same time as the new wheels, went with mechanical because I didn't want to deal with bleeding hydraulics, though this is the one thing I would change. I would get hydraulic brakes because I feel like I'm adjusting the pads on the mechanicals every ride or two (huge pain in the butt). Also bought avid FR-5 levers $16

handlebars - Ritchey comp alloy $30. crashed and bent my bars pretty good. I didn't want to change out the stem so I bought the closest approximation to the stock bars that I could find cheaply. also decent 25.4mm mount bars are freaking impossible to find.

I should note that this is certainly not the proper way to maximize the quality of the bike for the money. The total is around $700, though I've spent more than that over the 4 years I've had the bike since I've replaced a couple things multiple times (chains, etc.).

if you want a retro bike, these are the best things that I've found to replace the components as they break. If others have found better stuff in terms of bang for your buck, let me know. The only things I've replaced to "upgrade" the bike are the fork & disk brakes, though since it was time for a new wheelset the brakes made a lot of sense to purchase at that time.

This is the one I picked up, not sure if it has the clutch on it though. It does seem to shift better than the stock derailleur.

http://www.amazon.com/gp/product/B000YBCNAA/ref=oh_details_o09_s00_i00?ie=UTF8&psc=1

They make them in both 9 and 10 speeds. With the XT 9/10 speed stuff you need specific derailleur for 9 or 10 speed for some reason.

The rear D for 9 speed is the M772 or M773. Also, the Deore SGS is a good choice, this is what came on my bike and it's the same derailleur, just a bit heavier.

The 10 speed rear is the M781