grall1126

I have a Dura Ace 6sp-7sp shifter on an old bike with downtube shifters. I changed the cables and the problem I have all of a sudden is this

The chain is around the small cog on the rear wheel. When I shift upwards into the higher sprockets if I let go of the shifter the chain automatically goes to the small cog in the rear. The derailleur doesn't want to hold the chain in the proper spot.

The shifter will move the chain upward but once tension is off, boom back down to the small sprocket

Unca_Sam

I think the problem is in the friction setting on the shifter not the derailleur. Tighten the screw for your right shifter a little, until it can hold the derailleur at the largest gear without slipping.

masi61

grall1126 The issue is with your shift lever. It can’t hold the tension from the derailleur spring. I assume you are running down tube levers in friction mode? If you switch to index mode the detents between shifts will eliminate the problem. If you intend to stay with friction, I would say you should disassemble the rear shifter down to the washers, bushings, shifter body and tension screw. Then clean everything with a non-slick cleaner (no WD40 or silicon containing waxy products) reassemble the washers and bushings dry and snug up the tension screw and reinstall and re-test. Hopefully it was just a matter of some slick substance getting into your shifter and now it is holding. Let me know if this suggestion describes your issue or if I am missing the mark.

Iride01 

Friction shifter? You need to tighten the friction on the shift lever. Sometimes if the adjustment is worn out or put together wrong on the lever, then it won't ever stay put unless you tighten it so tight that the lever won't move.

Unca_Sam

Also, your picture makes it look like you're close to small-small gear combination. The chain doesn't rub on itself when you're in the smallest gear and smallest chainring, does it? A rubbing chain means the chain is too long.

JohnDThompson 

I suspect that the lever is too loose. If you're using the SIS downtube levers, be aware that (unlike other downtube levers) the D-ring on the right (rear derailleur) lever is not used to set lever friction, but rather to select between "friction" and "indexed" modes on the lever. Using it to set lever friction can damage the indexing mechanism. To set lever friction, use the screwdriver slot in the lever mounting bolt:

grall1126

sorry guys for the late response, you are right, that darn lever was loose, can't believe I didn't check it and immediately went to the cables.

alcjphil

When it comes to derailleur drivetrains, the shifters are the brains of the operation and the derailleurs are the blue collar workers. The cables are the chain of command