So I replaced the chain on my 1984 Fuji touring series IV bike that I am fixing up. Unsurprisingly, the new chain did not work with the old gears well. What do I need to replace to make the new chain work?

Based on what I found online, I think I have a freewheel, and I know that will need to be replaced. Do I also need to replace the derailleur gears and/or the chainrings? Does anyone have any advice for someone doing this for the first time?

What new chain did you use, and what kind of issues are you having?

You do not specify what type of problems you are experiencing, which makes this a bit of a guessing game. Here are a couple common issues:

Yes, you have a freewheel, not a freehub. Putting a new chain on a worn freewheel often leads to problems, specifically, when the chain is on the smaller cogs on the freewheel it will often fail to seat fully and seem to "skip" particularly when applying a lot of pressure on the pedals. If this is the type of problem you are experiencing, the solution is to replace the freewheel as well, so the new chain will properly seat on unworn cogs. Be sure to get a freewheel with the same number of cogs as your current freewheel to avoid having to replace hub axles, re-space the axle nuts, re-dish the rear wheel, etc. Your picture seems to show a six-cog freewheel, which should be readily available. To minimize problems with chain jamming during front shifts, get a chain designed for seven or eight cogs, rather than nine of more cogs. Chains for six-cog blocks are not advertised as such any more, and a seven or eight cog chain should work fine.

From the pictures that you posted it looks to me like you have a seriously bent derailleur hanger. The arm on your derailleur needs to be parallel to your freewheel cogs and I don't think that it is. That would definitely screw up your shifting.

I was wondering about this, too, but thought it might just be the perspective of the picture

I noticed that the quick release skewer is open in the photo - that could cause the rear wheel to move when pedaling.

Sorry I forgot to say what the problems I'm having are.

Yes I'm having problems with the chain seeming to skip. The chain seems to do alright in the larger cogs but when I shift to the smaller ones or try to pedal relatively quickly, it seems to skip.


Also, I have a kmc chain made for (I think) 6-7-8 speed bikes. It fits perfectly on my bike now.

Could you elaborate on this more? I wondered if something might be wrong with the derailleur because the shifting has been iffy since I bought the bike. And, when I tried to take the back wheel off to check to take a photo, the wheel kept getting stuck on the derailleur, which seemed abnormal to me.

The derailleur cage that holds the 2 pulleys, should be perpendicular to the ground. If the bike's been crashed on the derailleur side, the dropout (frame tab the derailleur attaches to) may be bent inwards. Very hard to tell over the internet. You can "eyeball" it from behind the bike while shifted into a gear that make the cage about vertical. The best way to tell is with a dropout alignment tool.

So that's 1 possible problem.

2) A new chain on a worn freewheel (or cassette) will often skip in the most used gears. You can buy a replacement freewheel cheaply. You need the correct tool, and a vice, or big wrench to remove yours. Or bring the wheel to a bike shop.

It's easiest in remove/install the wheel when on the smallest cog.

Chainrings and pulley wheels are probably fine, unless they look "shark finned" ...

Make sure your new chain is long enough to handle the big chainring, big cog combination. A chain that's too short can really cause damage if you try to force the big-big combination while riding. better a bit too long than too short.

The small freewheel cog looks to has worn teeth. With a new chain no wonder it skips under pressure (but likely not when soft pedaling). Replacing the freewheel will cure this and also get you cogs with current shifting/teeth contouring. The bent der hanger was the first thing I noticed. Important to fix not just for shifting performance but also because the cage/pulleys are now much closer to the spinning spokes...


BTW you might be able to fit a 7 speed freewheel in the same space that the old 6 speed one uses. Not that you'll go faster but you might get closer gear ratio differences. Andy

Would you say any of these look "shark finned?" (Sorry for the bad picture quality of the derailleur wheels.)

Is that a Mount tech rear der? If so then the showing wear guide pulley will be a challenge to find a replacement. The middle ring also shows wear but likely not enough to currently cause skip. Give it time... Andy.

Yes it's a suntour mountech derailleur. I've slowly been finding out the annoyance of trying to fix up a 30 year old bike with original parts.

Is it possible to just replace the whole derailleur? Or is that just exorbitantly expensive?

Also here are more pics of the derailleur. I can't figure out for the life of me if anything is bent on it. It doesn't seem to have a standard derailleur hanger but something does look off about it. Will it be easier to tell if I put the rear wheel back on and look at it that way?

This der, like most, mount to a tab which accepts most other ders. (there's a few Euro exceptions) In this case the tab is an extension to the drop out, not a separate plate. It is this extension that is likely bent WRT the axle/freewheel.


Most ders from that one's era or more recent should fit. Of course the gearing specs must match up with the der's capacity to wrap chain and clear the large freewheel cog. The Mount Tech was a friction control levered design. So assuming your shifter is still the OE friction one there will be no cable pull actuation ratio (indexing) incompatibilities.


A replacement der could cost from $5 for a used to over $50 for a new one. Assume on a new cable and casing. Andy

If you really don't know what you are doing, I would just bring it to a bike shop and have them take a look. They will quickly tell you if the hanger is bent and can straighten it out for you if it is. Pretty much every used steel bike that I have bought from the 70's - 80's has had a bent derailleur hanger. It's a quick fix if you have the right tool, and it makes a big difference.

You need to replace the freewheel. Freewheels (Thread on Type) for Bicycles from Harris Cyclery