Shimano 600 sis index shift adjustment.
 

I took the 1987 Schwinn super sport out for a nice ride today after work. The bike is a very sweet riding bike. The only thing is that it sounds like the index shifter or rear derailleur has to be tweaked a little. It sounds like the chain is between gears ever so slightly. Any help or suggestions would be greatly appreciated.

Asking as I have no context as to your tuning ability or experience level setting up your own bikes: are you familiar or know how to tune a rear derailleur? This information is easily obtained via research, though the simple answer is 1) adjust your upper and lower limits (of your rear derailleur) to make sure those are not allowed to go further than they should and 2) where the shift cable/cable housing goes into the rear derailleur, that is a barrel adjuster that allows you to adjust the tension on the rear derailleur cable, thus allowing you to tune it/adjust the tension. Righty-tighty to slacken cable tension, lefty-loosey to increase cable tension.

Has the shift lever indexing mechanism been oiled in the past 25 years?

Is the cable lubricated at the bb cable guide, and is the housing in good condition and lubricated? It should be a lined housing, better yet the modern stuff.

Starting there, adjustment of the cable tension should produce fruit. Elsewise, perhaps the cable is not in the groove at the derailer's pinch bolt(?).

watch this video from park tool

I have quite a bit of experience on friction shift but index is new to me. So all the index shifts happen in the shifter then ? I still need to service the shifter and derailleur. I just bought the bike last week and i have been doing a little research online. I appreciate the help and tips on where to look.

Good news: by and large, these indexed shifters essentially never (as in like 99.99999999% of the time) need an servicing or lubrication. It's pretty remarkable to dig up mid- and low-end SIS shifters from the late-'80s and early-'90s, put them on a bike, and have them work just fine. If the bike is in remotely decent shape, which it sounds like it is, you could clean the RD jockey pulleys or just leave them, tune the RD, and ride for a million more miles.

There should be a barrel adjuster and spring on the rear derailleur where the housing ends. Make sure your housing is SIS and not spiral wound. You turn that barrel adjuster just like you would one on a brake caliper. It's used to fine tune the derailleur.

Cheers

the bike is in fantastic condition and looks like it was not ridden much. The shifter is 600 ex and can be turned from index to friction. This is the first index shift i own and it can spoil you . Being used to friction shifting.
https://cimg0.ibsrv.net/gimg/bikefor...a19a99fe15.jpg

Nice bike!

I think that perfected index shifting is one of the biggest advances in bicycling. I too like it when I can use a shift lever in friction mode if needed. That can happen if the bike falls over or someone kicks t he rear derailleur.

You should be able to get the derailleur adjusted for quite smooth operation in index mode.

Cheers

Looks MINT! Love the colors, and agree, indexed shifting is really nice. Not that friction can't be, but...indexed, hello!

95% of the time my indexed bikes shift sloppily it’s because cable tension got too slack. It’s the first thing I’d check.

That’s a really nice looking Schwinn. I also have a few bikes with Shimano 600 SIS. I understand the index is in the shift lever. It ratchets to equally spaced Index positions. The spacing between each shift lever Index position will pull just enough cable to move the rear derailleur by one cog. The derailleur upper guide pulley also has a little freedom to move side to side to help the chain to lock into position on cog and reduce sensitivity to slight misalignment (or that’s what I think).
But over time the cable will stretch, so the index positions no longer cause rear derailleur to line up perfectly with rear cog. This causes the rear derailleur to sound like it is ready to shift. Or maybe it will shift under load (ghost shifting). So you need to slightly adjust the cable tension to re-align the index positions to perfectly align with the cogs. You use the rear derailleur barrel adjuster to do this. Screwing barrel adjuster out tightens cable. A small adjustment like 1/4 turn can go a long way. Do small change and test the result. Once adjusted it should be good for at least a year.

That's a tight machine! Love the white bar tape. Eddy Merckx is on my mind now!:giver:

I found it on letgo for 100 dollars. Even the frame size is exactly my size. I was thrilled at its condition. Even had its original tires marked Schwinn. But they are really dry rotted. New tires and tubes and i have to regrease the bb and rear hub.

One thing (besides the modern cable housing) that will really improve the shifting would be to get rid of the original 8mm wide chain. Even if it's the genuine Shimano Uniglide, the subsequent "UG Narrow" and all newer 7s/8s chains will make shifting quieter and more forgiving, as well as being much more tolerant of scant lubrication (making it easier to maintain a clean-appearing chain). The modern chain is also lighter and wears well if it isn't the cheapest grade. Look for Shimano HG70, KMC X-series, or Sram chain for good product.

Your Super Sport is a particularly nice example of that model. I ride a 1971 Schwinn Supersport and also have a 1979 Peugeot Super Sport that I like, but yours is lighter and more modern than either of those bikes.

It looks like your bike is old enough to have coiled SIS cable housing going to the rear derailer, not a big deal but switching to the modern, incompressible type (with appropriate ferrules) will further improve shifting accuracy.

Most likely just a simple cable adjust at the derailleur as many have mentioned. Odds would be the cable has slackened so you would “unscrew” the barrel adjuster counterclockwise. If you have a stand you can mimic tightening the cable by lightly pull on the cable at the downtube run. If the chatter stops, you need to tighten.

Other possible, less likely causes:
-Chain is stretched and worn
-Cog is worn
-The cable or housing is worn or oxidized and not moving freely

Twer me, I’d start with the Park video in the earlier post and see if you can dial it in with a cable adjustment. Good luck!

The stand i ordered on amazon just came today. Not bad for 50 bucks. Am going to clamp it up and do the rest of my cleaning. Bottom Bracket and rear bearings are next on the list to clean. Then will mess with shifting. This bike has very little wear and tear. The poor bike must have sat for almost all its life. What a shame cuz it rides so well.