rtcumminsjr

Hi,
I have a 1970 Schwinn Continental for which I have upgraded the rear derailleur to a GT400 from a GT100. The only issue I have is that if the chain is on the smallest rear sprocket and the pedaling pressure is great (when I really should shift to a larger sprocket) the chain skips over this smallest sprocket. I shift the rear derailleur to a lower gear and then there is not the skipping. I do not think it should be skipping in any condition. Am I wrong? I just want to make sure I have everything adjusted correctly. I just restored the entire thing from the rust bucket it had become over the 50 years I have had it. It has gone from kid treatment to antique treatment as I have become an antique as well.

Thanks,
Bob

Purchased May 31, 1970 with my newspaper route money. Celebrating its 50 year and Schwinn's 125th anniversary with complete restoration.

andrewclaus

Did you replace the chain at the same time as the rear deraillieur? Is the freewheel new? It's unusual in high gear, but a new chain often jumps on an old freewheel.

If it's an old chain on a new freewheel, check the chain for "stretch" and twisting damage.

Edit; By the way, congratulations on your project. I had that bike in Chicago. I got it used in 1975 (high school graduation), sold it in 1982 when I got married, and my wedding present was a new bike. Mine was yellow.

bldegle2

New derailleur, check alignment of hanger, reset the indexing high and low, then adjust the cable for smoothness. Sounds like your indexing is off a bit, that is why your chain is skipping in the small ring. It is to be expected with a new derailleur, takes a bit to get it adjusted right...

Bill Kapaun

Worn chain OR cog will cause skipping. Worn chain AND worn cog might not.

JohnDThompson 

A 1970 Schwinn Continental pre-dates indexed shifting by many years; unless the chain, shifter and freewheel were updated at the same time to indexed-compatible components, this is a friction-shifted bike. But the OP's description of the problem suggests otherwise. The problem described is probably the chain failing to seat properly on a worn freewheel sprocket. This happens most often on the smallest sprockets because fewer teeth will wear faster than on the larger sprockets. Under hard pedaling, the chain rides up on the worn teeth, the wear means the tooth spacing no longer matches, and the chain jumps when it fails to cleanly engage with the next tooth. The fix is to replace the chain and freewheel with new components.

rtcumminsjr

Thanks. I replaced freewheel with a much less used Schwinn Approved one of the same era (Schwinn Approved Model J Freewheel 5 speed 14 - 28, from a Model G) The chain is new. Always fond memories with a Schwinn!! Thanks for your story!

rtcumminsjr

Thanks. I replaced freewheel with a much less used Schwinn Approved one of the same era (Schwinn Approved Model J Freewheel 5 speed 14 - 28, from a Model G) The chain is new. Always fond memories with a Schwinn!! Thanks for your story!

rtcumminsjr

Thanks. I replaced freewheel with a much less used Schwinn Approved one of the same era (Schwinn Approved Model J Freewheel 5 speed 14 - 28, from a Model G) The chain is new. That helps me to understand that it is perhaps a consequence of what I want to do---have period parts. The small sprocket does not skip unless it is under tension that warrants shifting to a lower gear. Your response takes the burden off of trying tweaks in other places that would not help at all. I have the original chain but it was used with the Model G---which has rounded teeth!

rtcumminsjr

thanks for you help!!!