pietro

Hi, I'm 62 and I just got my first bike ever, a 12 speed '85 Schwinn Le Tour! Yes! Happy First Bike! Well, not quite right, my knowledge of possessing solely my own bike was: "pure fun ahead", I was brought down to earth as I was lying on the ground, talk about redundancy! After removing the old tires I went for my first ride... the rear derailer broke as I was shifting speeds, even if it was at a very low speed the derailer ended broke in half and bended in several places, I ended up, down is more correctly, wondering, did you see the rhino?, anyway, I'm a dedicated consistent-stubborn "fix all", not this time!

Did I do something wrong when shifting? Something not assembled correctly after changing the tires? I'm pretty sure everything was tight. Was it a great but tired honorable de gaulle derailleur? I need hints about handling friction shifters and old 6 speed derailers.

My budget is small, what is the right derailer to order? Do I have to get an old model or a new model will do a better job? Please somebody help me, I can use some suggestions and directions.

Thank you for your kind help,

Clamber Felicce

Homebrew01

On older bikes "almost" any derailleur will work - old or new, because they don't have the compatibility issues that newer bikes have for indexed shifting. Depending on the frame, some derailleurs have an extra hanger that attaches to the frame to make up for the lack of hanger built into the frame.

If you post some close-up pictures of the rear wheel area, you will get a better answer.

Panthers007

Yep - most any modern derailleur will do the job, unless you're thinking of installing an indexed-shifter. For a friction-shifter set-up, it's no problem. I personally prefer a friction set-up on road-bikes.

Al1943

If possible take it to a local bike shop that is use to working on older bikes. Finding a derailleur that is compatible with your particular frame may be an issue, I don't know.

tatfiend 

Sounds to me like the old rear derailleur had the stops misadjusted or a frozen cage pulley so that the chain tore it up immediately. 85 is late enough so probably not one of the plastic French derailleurs so almost any rear derailleur should fit. You may have also bent the derailleur hanger so a visit to a bike shop would be recommended for getting things checked out. They should also be able to sell you a new derailleur and install and adjust it properly.

pietro

Thank you for your fast response Homebrew & Panthers, I'm attaching a couple of pictures.

What about the reason for breaking right at the thick metal part? Did I messed up something after removing the tires? Or the crack was already there? See broken derailer please.

Felicce

Panthers007

Have a shop take a look at it and get a new RD (rear-derailleur). Can't tell much from those pictures, but it's broken and needs replacement. And speculation on what caused this is just that - speculation.

Good luck. It shouldn't set you back too much money. RD's are pretty cheap and they last many years. It's unusual for them to break under normal usage.

pietro

Hi Tatfiend, I got your reply the second after I sent two pictures.

You are right it did bended the frame at the point of attachment and the tire wheel. Now, what do you think, old and defective derailer? was not the fact that I shifted kind of rude and broke it? not possible?

Thank you,

Felicce

Panthers007

A shop can determine if your derailleur-hanger is bent - and fix same in 5 minutes. Could be you shifted it into your spokes by mistake? This can happen with a bent hanger.

tatfiend 

If properly adjusted, and with the hanger not bent, a rear derailleur should not break due to shifting as long as you are pedalling forward when doing so. A derailleur shifting setup must have the chain moving forward to shift as the derailleur just positions the chain to change sprockets as it travels forward.

Normally rear derailleurs are not damaged by shifting unless they are not adjusted properly, the derailleur mounting is not properly aligned or a pulley is damaged or frozen. There are two stop screws on the derailleur that must be properly adjusted to prevent the derailleur from overshifting into the spokes or shifting out too far and allowing the chain to come off of the outer rear sprocket.

tatfiend 

I would add that a bad enough chain with frozen links can also cause derailleur damage. Trying to analyze after the fact though is speculation without the bike and parts in hand.

pietro

Hi Tatfiend, you're helping me to learn a lot and fast. Where can I read to learn about derailer function and adjusting the screws?

Question: why some derailer pulley wheels have 10, 11 or 13 teeth? it's related to what other part of the bike?

Thank You MUCH!

Felicce

Road Fan

Proper chain length (not too short) is another requirement.

Road Fan

There's an excellent old book that dealt very very well with bikes of this vintage: Anybody's Bike Book by Tom Cuthbertson. There's a copy available on Ebay as of last night, $7.99 buy it now. I think this is worth it. I don't think you'll find such a good beginner's manual by surfing the Web.

curbtender

Hi Pietro, You said you had the rear wheel off and reinstalled it? You may have routed the chain wrong while doing that. Usually it's not so catastrophic as that, but it happens.

I'm seeing the bottom pulley at the top.

Panthers007

As long as it's first edition, I agree. He has a wonderful writing style and his pal doing the illustrations is great! "Tuck and Roll handlebar-tape?" Very timely - a time when if you smoked pot, you wouldn't lose your house to the Nazi's and have your children taken away for keeps.

tatfiend 

The number of teeth on the derailleur pulleys has no effect on anything else. Some newer derailleurs use larger pulleys in an attempt to minimize chain bend radius where it runs over them.

Another good book IMO is Glenn's New Complete Bicycle Manual. Usually available on Amazon used and very complete.

pietro

Hi, I went ahead and got me the book on ebay.

I've learned a lot in the last 24 hours with you guys!

Thank You!!!

pietro

Hi Curbtender, that picture is after the accident, I try to put it back together just to take a picture, it broke a few hundred yards after I got on the road. It happen the instant that I pull on the right shifter for the first time. I agree with you that I did something terrible wrong after reinstalling the tires, I can't ignore that it was my first time removing wheels and replacing tires, anyway, I'm just looking for as many answer as possible to be more careful next time.

Pietro.

Panthers007

For simplicity:

The chain goes around the derailleur in a backwards 'S' shape.

garage sale GT

Interesting. I broke a rear derailleur on an '85 World Sport while shifting. It bent the hanger. I think I may have bent the derailleur by snagging it on something a few miles previous, leaving it unable to shift properly. I didn't stop to check after the first incident so I'll never know.

I just popped on a $9.99 Shimano Megarange rear and it worked fine. It was new, not one of my vintage parts. The drawback to getting a long cage derailleur though is that the action is not as fine and you have to overshift a bit then adjust it back.

pietro

Hi, same here. it seem like I'll never know.
So what are the the advantages on a long cage?
Pietro.

pietro

Hi, to upgrade from tension to indexed shifters what would be the advantages?
Pietro.

Al1943

A long cage derailleur is needed when there are large differences in the physical sizes of the gears. This is especially important for triple cranksets. When the chain is on the smallest chainring there is more unused chain that would be slack if not taken up by the long cage rear derailleur. "Chain wrap capacity" is a function of rear derailleur cage length.

Al

Al1943

Index shifters have "detents" or "click stops" that quickly align the derailleurs with the desired cog. Friction shifters usually require some trimming to optimize a shift.
Suggest you spend some time searching around at https://www.sheldonbrown.com. You will find many definitions and explanations.