Rear Derailleur tightness

[sportstourer74]

I recently purchased a 1974 Schwinn Sports Tourer. Although the rear derailleur (Le Tour) worked fine when I bought the bike, it has since started to tighten up, causing the chain to rub against the gears and cause a clicking sound/vibration. I have tried adjustments and looked online to no avail. Any info would be appreciated!!!

Thanks

SEE VIDEO FOR PROBLEM

[xerxes]

Take a look here: http://bicycletutor.com/adjust-rear-derailleur/

If you tighten the B-tension screw, it should hold the derailleur further back and keep the top jockey wheel from touching the sprocket.

[sportstourer74]

I actually saw that video, but do not have a visible b tension screw. I searched all over for it and could not find anything on the top, side, bottom, etc.

Any other ideas?

[xerxes]

I did wonder about that, I have a Shimano derailleur, the Schwinn Le Tour is made by Shimano, and that has no B-tension screw either and has the same problem when on the largest rear sprocket.

If there's no way of moving the derailleur backwards, I don't think there's much you can do about it.

Having said that, have a close look at the top pivot, is there another means of rotating and holding the thing about the top pivot? I was looking at this : http://www.disraeligears.co.uk/Site/Schwinn_GT400_Le_Tour_derailleur.html and there appears to be some mechanism at the top pivot, but I can't really see what's going on.

[sportstourer74]

That photo is my derailleur, exactly. I have tried rotating it or pushing it back, to no avail. I guess I should try again.

[trevgbb]

if I remember right, many old style RD's did not have a b screw, but had a stop pressed out of the metal of the body which was supposed to stop the RD coming forward, this may be damaged or has been over ridden, examine the back of body for this?

I also suspect your chain is a little on the short side.

[Bill]

Ok I am going to take a poke at this. That almost looks like the chain maybe too short? The angle of it in the top gear is pretty stretched forward? Not pro on this as I have a newer 80's version of the traveler.

OR maybe adjusting the bolt that holds the derailler to the frame, maybe unloosen it then pull back on the derailler then tighten it again???