02Giant 

Does the bike fit? If so, then replace the chain ring, chain, cassette, and jockey wheels or just replace the derailleur. Don't worry about a chain keeper until you have a properly functioning drive line.

While you are waiting for parts to be delivered, you will have time to clean...

tomtomtom123

If it's that old, you might also want to check the bottom bracket and hub bearings. And maybe the pedals.
But if you just want to be able to pedal without the chain falling off, then you absolutely need new cassette, chain, chainring, and pulley jockey wheels. Total around $60 if you get the cheapest parts.
If you also want to replace the bottom bracket for smoother power transmission, it's another $12-15.
I think you're going to want new tires. You can buy good Schwalbe Marathon tires for around $30 for a new pair of 2 tires.

Although, I went to the local big bike shop yesterday, and they had for $300 the cheapest new bike with 3x7 drivetrain.

oldbobcat

The chain is severely elongated (worn out), the teeth on the derailleur pulleys are almost completely worn off, the cassette is worn out, and the chain is too long as installed. I'm looking at the gap between the chain links and the front chainring in the last photo, and it looks like the chainring is the only part of this drivetrain that isn't toast.

frugihoyi

Thanks for all the advice. I'm planning to replace my entire drivetrain. I've found some parts on Chain Reaction Cycles. What do you think of these? Will they fit on my bike and are they ok quality? I went for the cheapest of everything.

Derailleur
Some of you have suggested that the derailleur hanger might be bent, so I thought I should get a new derailleur, which already includes the jockey wheels I need to replace anyway.
My cassette has 11 teeth on the smallest cog and 28 teeth on the largest, so I guess this fits, right?
I have 9 speeds so that seems to match.
It says Use: MTB and mine is not a mountain bike. Is this a problem?
Anything else I need to consider?

Jockey Wheels
This is if I don't get a new derailleur (incl. jockey wheels).
It says 9-speed, which matches what I currently have.
Like the derailleur above, it says this is intended for MTB, but my bike is not a mountain bike. Is this a problem?

Chain
9-speed

Cassette 1
9 cogs, 11-28t

Cassette 2
9 cogs, 11-28t

Chainring
It has the following specs, which match my measurements:
46 teeth
5 bolts
130mm BCD

tomtomtom123

Derailleur looks ok. Hanger is not part of the derailleur, so you might still want to check the straightness of your hanger. The label MTB on a shimano 9 speed RD doesn't really mean anything, as all of the shimano 9 speed RDs have the same cable pull ratios, and 9 speed cassettes have the same physical spacing. The MTB label might indicate a larger highest cog size and larger chain wrap capacity. The one you linked is the SGS cage length which means it has a very wide chain wrap capacity.

Chain is ok. You could also look at KMC or Shimano chains. Some have quick links that are easy to install and disassemble. KMC are generally reusable links. But if you're just going to put it on once and never take it off until you are replacing the whole chain, then a quick link might not matter to you.

Different brands have different cogs in between the 11 and 28, which will change the stepping between the gears. You might want to search on the internet for the actual stepping. You can also think about whether you want to change to 11-30, 11-32, 11-34, 11-36, or even having a 12T first position cog, to adjust your gear range. I mix cogs from different cassettes to make my own custom mix.

Same with the 46T chainring. You can think about whether you want to get a smaller number of teeth to reduce your gear range, in case you feel that you don't need the top gearing and want to adjust to lower gearing. The TA Alize chainring that you linked is for the inner position, which means it mounts to the inside of the flange, which is ok. It's got no ramping and is symmetric and flat. If you want smoother running of the chain while on the innermost and outermost cogs, you could look at using a narrow-wide chainring, which as alternating narrow and wide teeth to help a 1x chain run quieter at the extreme angles.

If you just want to buy the cheapest replacement parts, I guess what you listed would work.

Don't forget to buy lubricant.
Also you might consider new tires if your old ones are completely bald.

you'll need some tools if you don't have any. like 5 and 6mm hex keys, chain breaker, and something to cut the crimp off the cable. you might want a new crimp end cap after you reattach the cable to the new RD

frugihoyi

Oh I see that now. If I want a strong hanger that won't bend easily, what material should it be made of?

Do you mean that if I buy a 11-28 cassette, the cogs in between the smallest and the largest might have different numbers of teeth than in the cassette I have now? Could that cause me problems or will the cassettes I linked to work for sure?

Can I actually get a smaller number of teeth and not run into any problems when combining it with the other parts I listed? Are you saying all my geras will be heavier with a smaller number of teeth?

alcjphil

Hangers are designed to be sacrificial if the derailleur is hit in a fall. They are all made of a material that is softer and more malleable than the frame and the derailleur itself. The hanger can easily be replaced for less money than either the cost of a new derailleur or, much worse a damaged frame

tomtomtom123

There are hundreds of different hangers. You would have to find one that matches your bike frame. I don't know what materials are available. The ones that I have are either replaceable aluminum, or a steel hanger that is physically part of the frame and not removable.

Different sized cogs in between the 11 and 28 won't affect the shifting ability of the bike. Both of the cassettes in your links should work. But it will affect how much power difference you will feel between the steps of the gears. For example if you have a pair of cogs that are 19 and 21, the difference is 10.5%. If you have 19 and 22, the difference is 15.8%. You can search google for gear calculators if you want to see what the gear stepping looks like.

Using smaller number of teeth in chainring will reduce the gear range. It does not make it "heavier". If you use a smaller chainring, you have to check if the chain gets too long. But since you are using a RD with longer cage, you should also check if you need to cut the new chain longer than the old chain.

Narrow wide chainrings are designed for 1x setup. It's not absolutely necessary, but it makes the chain run quieter and helps sometimes to keep the chain from jumping off because of the taller teeth.
https://www.ebay.co.uk/itm/J-L-Narro...-/301933208383

AnkleWork

This is the same philosophy that replaces a blown fuse with a higher Amp rating because the fuse must be the problem.

FYI, the purpose of a replaceable hanger is to protect the frame. Thus you always want a hanger that's weaker than the frame.

frugihoyi

There is something strange about the chainring I linked to. It doesn't actually seem to have the same diameter, have I calculated wrong? Below you can see a photo of my bike with the chainring, followed by one with an overlay of the chainring I linked to.

trailflow1

Are you sure your old ring is 46t ? Have you counted the number of teeth ? it looks like 48t or 50t.

The overlayed photo only has 39t so the circumferance of that ring is alot smaller. There is quite a big difference between a 39t and 50t ring in size.

tomtomtom123

You should also check whether you have 110mm or 130mm BCD

jbucky1

1) wash it
2) Put a new chain on it
3) Put on some new derailleur pulleys - those are garbage

- james
www.buckyrides.com

02Giant 

4) Replace the cassette
5) Replace the chainring

jbucky1

Thing does look pretty thrashed, so yeah, might need a new cassette and chainring. I would start with the others first then see, since a new cassette and chainring are more expensive than the others.

- james
www.buckyrides.com

frugihoyi

I want to clarify a few things.

I did spend four hours cleaning this bike but there was so much gunk deep in those hard to reach places that I think the only way I could have cleaned it properly would have been with a high pressure washer, which I didn't have access to. Also some time has passed so it's accumulated more crap in the meantime. I can see it's time for me to clean it again but that job will be much easier since I'm now planning to replace the entire drivetrain, which is the hardest part to clean.

I double-checked my chainring, it is indeed 46t and 130 BCD. The overlay picture I posted is wrong because it comes from the product page, where they sell the same product with different numbers of teeth. So it seems like the picture they posted wasn't for the version I'm ordering.

The hanger for the derailleur doesn't seem to be bent.

I think most things are clear to me now and I know which parts to order. I just have one more question:

As I wrote before, my current cassette is 11-28t. Can I replace it with 11-32t and will that work without changing the specs of the other parts?

Alex1098

I totally agree but for sure... WASH IT

trailangel

Hanger is bent.
One of the dirtiest, worn out POS I've ever seen. Replace everything.

frugihoyi

That was unnecessary and how do you know if the hanger is bent?

JoeTBM 

I agree
Some people are either just cruel, have no common sense, or ignorant....
possibly all of the above.

trailangel

I can see the hanger is bent.
I'm not going to sugar-coat it for you.
You need a new rear DR.
You need a new cassette.
You need a new Chainring.
You need a new chain.

tomtomtom123

You should never use a pressure washer hose to clean a bike. you'll force water into the hub, bottom bracket, headset, etc.
I still think you need to inspect your tires. They look bald and worn out in the photos.
Other moving parts to consider are the bottom bracket, and cleaning and regreasing the hub bearings.
Although the pedals are slow moving, you might want to check if the bearings in them are corroded or dirty.

The hanger can be bent back straight as long as it hasn't been hit and bent too many times. You could borrow a hanger alignment tool from someone if you don't want to buy the tool.

frugihoyi

So I've changed the entire drivetrain: chainring, chain, cassette, and derailleur. I've been riding for over a week and I'm happy to say I haven't had any more problems.
P.S. the hanger was not bent, as one rude poster so confidently proclaimed... despite the fact that I had already checked it and said it was not bent

Here are some pics:

02Giant 

Great job!
Unfortunately everything was trash, now you are set for a while. Keep your chain lubed.

bldegle2

Nice job with the fix. Only one thing I noticed the rear derailleur cable housing is too short, it is setting at a fairly sharp angle on the derailleur cable entrance. Simple fix when you get a chance. The way it is now is a recipe for cable fray...Cheers...