Chain issue with my "9 Speed" Nishiki
 

Hi all.

First, a thank you to everyone on this forum who weighed in on my shifter upgrade from downtube shifters. After considering an upgrade to index shifters, I ended up staying "analog" and going with some dia compe bar end shifters instead. Very happy with them.

On to my current problem.

I have a drivetrain that is effectively a 9 speed at the moment. If I try to go to the large chainring - largest sprocket combination, the chain comes up short, maxing out the derailleur and locking up the chain so tight that I have to take the wheel off to release the tension and reset the drivetrain.

I think I still have the original chain on the bike, so I bought first a 7.3mm 1/2" x 3/32" 116 link chain designated for 5-8 speeds and installed it.

At the 116 link length, the new chain would let me get on to the large chainring - largest sprocket combination, but the chain would then skip-jump when on the two smallest sprockets,

I took out first 2 links (to 114 net links), then 4 links (to 112 links) and the same behavior worked on larger three sprockets, skipped on the smallest two sprockets. Oddly, at 112 links, it would still go onto the large chainring - largest sprocket combination.

I then bought a beefier 7.8mm 116 link chain designated for 5-6 speed use, and I got the same results: skipping-jumping on the lower 2 sprockets, good on the three largest sprockets.

I (think I correctly) measured the legacy chain the with a caliper and came up with 7.96-8.0mm width (at the pin: I got 7.28-7.30 at the pin on the first chain and 7-76-7.80 on the second chain).

I no longer have the original Suntour "Blue" series derailleur, having replaced it with another Suntour derailleur with the same jockey arm (?) length.

So what do you folks think?

Is my drivetrain so old that I need an even beefier single speed chain?

Is my derailleur just tired (it probably has over 10,000 miles on it since installed) and not maintaining sufficient tension in the chain when at its most slack on the smaller sprockets.

I would really like to get over the hump on this 9 speed issue and have my Nishiki fully functioning again, so any insights/ideas would be most appreciated.

what tooth size are your two chainrings you're running and what's the largest / smallest cog you're using on the cassette? you might need a medium to long cage rear derailleur to shift cleanly depending on the big / small chainring / cog combinations:

I think your freewheel has seen the end of its useful life if it's skipping with a new chain. You should make note of the tooth count you have on the freewheel cogs and look for a replacement to go with your new chain. Chainrings wear a little slower but that wear is accelerated by a chain that is more out of spec than 1/2% (slightly more than 1/8" over 3 feet). If you pull the new chain as installed from the front of the chainring, can you pull it away from the chainring by more than a tiny bit?

There are lots of ways to size a new chain for your drivetrain, but the simplest is to put the chain over your largest chainring and cog, determine the length, and then add an inch. Tired derailleurs can lose your chosen gear on rough roads, but they wouldn't be the source of skipping.

I think you need to learn all about the important spec's you need know and consider when choosing a DR or changing the gearing up on a bike. Old or new components, they'll all work properly if you stay inside the spec's.

Know what the min and max cogs size is, max front difference and capacity of your rear DR among other things.

For 9 speed cassettes use a 9 speed chain
 

You have just verified the need to buy the right chain for your bike. It is determined by the number of gears on the cassette because as the number of gears increases, the width of the tooth is smaller. If you look up chains on eBay, you will see that sellers list 6-8 speeds as one chain and 9 thru 12 each a different chain. Here is what Wikipedia shows for chain width:

• 6 speed – 7.3 mm (9⁄32 in) (Shimano HG), 7.1 mm (9⁄32 in) (SRAM, Shimano IG)
• 7 speed – 7.3 mm (9⁄32 in) (Shimano HG), 7.1 mm (9⁄32 in) (SRAM, Shimano IG)
• 8 speed – 7.3 mm (9⁄32 in) (Shimano HG), 7.1 mm (9⁄32 in) (SRAM, Shimano IG)
• 9 speed – 6.5 to 7.0 mm (1⁄4 to 9⁄32 in) (all brands)
• 10 speed – 6.0 to 7.0 mm (1⁄4 to 9⁄32 in) (Shimano, Campagnolo)

You will see that 6-8 are the same but all the rest are different. Buy a 9 speed chain. Sellers also list the number of links in their ad. Here is one for $16 postpaid and it is a decent chain, one that I use in the 10 speed version on my recumbent trike. https://www.ebay.com/itm/304660205330

Other people have addressed the chain wrap, derailleur capacity, and chain wear concerns, but I feel I ought to clarify this bit:

A single-speed chain, with rare exceptions, will not work on a derailleur-equipped bike. Single-speed chains are 1/8" wide, while derailleur chains are nominally 3/32" wide. Those designed to work on rear clusters with eight or more sprockets are even narrower. A 1/8" wide chain will not be able to seat properly on a cluster designed for 3/32" or narrower chain. When replacing a chain for such a cluster, you need to get one designed to run on the number of sprockets your cluster has. You can generally use a chain designed to run on a higher sprocket count than what you have, but not vice-versa. The higher sprocket count chains tend to be more expensive, so you may as well use the one designed for the exact sprocket count of your cluster.

I double-checked the OPs other thread regarding shifters. He is using 10 speed to mean a 2x5 drivetrain, and saying he's lost the use of the large-large combination for a reason that's not immediately clear.

Good chance you bent something trying to shift with the chain too short. I'd start by checking the alignment. You shouldn't have a problem with an 8 speed chain unless you are running a 9 speed cassette, or am I misunderstand your rear gearing? Good pictures always help.

That's a pretty important bit of info...

Thanks for all the quick responses.

But boy, did I ever screw up in my subject line.

I have a 5x2 drivetrain (5 sprockets on the cassette, 2 chainrings on the crankset).

I was trying to make light of my 10 speed currently only having nine speeds available, the gearing defined by the large change ring and the largest sprocket being the one speed/gear ratio I can't reach because it runs of of chain.

Didn't think that a "nine speed" could also be a 9 x 1 so my bad for that confusion.

so again what size are your chainrings and the smallest and largest cog?

I owned a Nishiki Semi Pro 10 speed (2 X 5) a long time ago. If this is a similar vintage bike (mid 1970s) it has a freewheel, not a cassette. If this is the original freewheel with 10K miles on it, then it is probably worn enough that putting on a brand new chain may result in problems with gear changes like skipping. When I get a chain with this many miles on it I always add a new cassette at the same time. You can still find 5 speed freewheels online but you will also need a compatible freewheel remover to get the old one off. Most long time bike shops may still have the tool and can remove it for a small fee. You don't need the tool to get the new one on - it just spins into place. Sunrace makes a 5 speed freewheel you can get on eBay for $17 delivered and it is in the usual 14 to 28 tooth configuration likely to be what came on the bike new. https://www.ebay.com/itm/303797928556

Yes, you did confuse me. But it's also a normal state of mind for me!

you're right, it a freeweheel, not a cessette: I get those two mixed up all the time.

My sprockets range from 14 to 33 teeth.

My chain rings are 36 and 52 teeth.

Count again the number of teeth in the inner gear on the freewheel to verify the number of teeth. I don't remember an odd number of teeth for that one. It's usually even such as 28, 30. 32 and 34. Suntour obviously did make a 14-34, 5 speed freewheel because you can find used examples for sale for $$$$ on eBay (https://www.ebay.com/itm/255757832564). If you can live with a reduced gear range it makes sense to go with 14-28 because it is the only brand new one that sells for a reasonable price.

I really like that 32 (34?) creeper-gear sprocket. But it is a suntour freewheel based on the tool I need to remove it.

When you're touring with 15-25lbs of gear on a 20 mile 10% grade, that ratio sure comes in handy.

It would be easiest to pay the price for a 5 speed freewheel with expanded gear range. Otherwise you're talking about respacing or replacing the rear wheel and respacing the rear triangle to use 126mm spacing to fit modern kids bike 6 and 7 speed freewheels in there. You'd have no issues with the shifters, but you might need a new rear derailleur for it to work well.

Any possibility you could switch to an 6 speed freewheel? It would be a tight squeeze but maybe a possibility. Shimano currently makes the Tourney model in a 14-34 6 speed freewheel. You might have to buy it on eBay from China to get a reasonable price. Tourney is a fairly low end product but most of these are used on new entry level bikes so that's what is out there. It looks like the difference may be as little as 6 mm with 6 and 7 speeds the same for road bikes according to the Sheldon Brown website. https://www.sheldonbrown.com/cribsheet-spacing.html