Bicycle Mechanics - Which derailleur for an old touring bike?

I have an old (1984) Trek 620 touring bike with a worn out derailleur and I would like your opinions please on what to replace it with. The front chain rings are 50/45/28 and the rear freewheel is 13-28 6 speed.

I have been told a Shimano Deore, Deore LX, or Deore XT would work fine. These may be excellent choices for a modern bike, but too me they look awkward on an old vintage bike.

I also considering using a Shimano Ultegra GS (medium cage). I've noticed that Cannondale has a touring bike that comes stock with the Ultegra derailleur as shown here => http://www.cannondale.com/bikes/09/cusa/model-8TR1.html

The Ultegra derailleur may be overkill, but it sure looks sweet. What do you think? Do you have any other recommendations?

Any help would be greatly appreciated. Thanks!

It sounds to me like you've really already made up your mind on the Ultegra. I con't think of any reason why it wouldn't work.

Well, the capacity of a GS derailleur is around 33T while a SGS (like the Cannondale Touring's Ultegra Triple, which is different from the Ultegra GS) has a capacity closer to 45T.

Now, you need a capacity of at least (50-28)+(28-13) = 37T. This means that if you go with an Ultegra GS, which has too little capacity for your gearing setup, the chain will go slack in some gearing combinations. You'll also have no flexibility to increase the range of your cassette should you desire lower gears.

But hey, as long as you only use the three first rear gears while in the smallest chainrings, you won't have any trouble.

If you want something to look period correct and that would work very well, you can hardly go wrong with an old SunTour derailleur. I think they are vastly underrated. On the cheap end you could find a Vx or Vx GT. On the somewhat more expensive side you could hardly go wrong with a Cyclone. They have not been made in a couple of decades, but they are easy to find (even NOS) on Ebay or in a dusty corner of an LBS that has been around for a while.

jim

To Retro Grouch: I do like the looks of Ultegra derailleur. I guess what I'm asking, is there any reason not to chose the Ultegra derailleur considering my gearing. Thanks!

To hernick: Thanks for that. What I am confused about now regarding the Ultegra derailleur is the gearing compatibility specs. Shimano website list the specs as follows:

Model Number RD-6600-GS
Series ULTEGRA
Maximum Sprocket 27T
Minimum Sprocket 11T
Maximum Front Difference 22T
Total Capacity 37T

My gearing "Total Capacity" would equal the Ultegra's "Total Capacity". My largest rear cog is one tooth over the "Maxium Sprocket" spec. Is that going to be a problem ?

Another confusing thing is the Cannondale Touring 1 bike would not be compatible per Shimano's specs.
Cannondale Touring 1 gearing:
(50-30)+(32-11)=41T total capacity

This far exceeds Shimano's spec for the Ultegra. But somehow Cannondale made it work. Any comments?

To Jim: Thanks for the tip. I would like to keep the bike period correct. The orignal derailleur is a Sachs-Huret Duopar Eco. I'm on my second Duopar in less than a year so haven't had very good luck with them despite there high reputation. I'll check into the the Suntours. Thanks.

To Jim: Thanks for the tip. I would like to keep the bike period correct. The orignal derailleur is a Sachs-Huret Duopar Eco. I'm on my second Duopar in less than a year so haven't had very good luck with them despite there high reputation. I'll check into the the Suntours. Thanks.

I'm sorry to hear that, my Duopar is still going strong after about 30 years (most of them weren't me). Try a pre-Sachs one, it may just be luck, but my experience with them has been better (mostly just luck I'm sure)

SteveD: If you would like an Ultegra GS, how about paying $40 for one - brand new? No joke:

http://www.cambriabike.com/shopexd.asp?id=68265&page=SHIMANO+ULTEGRA+RD-6500+REAR+DERAILLEUR

I have 2 of them. They are excellent derailleurs. They will work fine on your combination. I have one running on a 13 - 28 9spd and triple front. Shimano specs are notoriously conservative.

I'm sorry to hear that, my Duopar is still going strong after about 30 years (most of them weren't me). Try a pre-Sachs one, it may just be luck, but my experience with them has been better (mostly just luck I'm sure)

My wife's bike is an '84 Trek 720 and we are having problems the Duopar on that bike too. I keep them cleaned, oiled, and adjusted, but they still wear out after 1500 miles or so. Is that normal?

Specifically what happens is the derailleur cage get's bent (somehow, probably us) and the chain keeps falling of the top jockey wheel. And there seems to be a lot of play in the derailleur linkages. Thanks!

SteveD: If you would like an Ultegra GS, how about paying $40 for one - brand new? No joke:

http://www.cambriabike.com/shopexd.asp?id=68265&page=SHIMANO+ULTEGRA+RD-6500+REAR+DERAILLEUR

I have 2 of them. They are excellent derailleurs. They will work fine on your combination. I have one running on a 13 - 28 9spd and triple front. Shimano specs are notoriously conservative.

Nice price on the Ultegra. Thanks for that!

Also, you have 13-28 in the rear. What are your front chain rings sizes? My setup got a granny gear (50/45/28) so I may need more "Total Capacity". Thanks for you help.

My wife's bike is an '84 Trek 720 and we are having problems the Duopar on that bike too. I keep them cleaned, oiled, and adjusted, but they still wear out after 1500 miles or so. Is that normal?

Specifically what happens is the derailleur cage get's bent (somehow, probably us) and the chain keeps falling of the top jockey wheel. And there seems to be a lot of play in the derailleur linkages. Thanks!

That's how my sachs met it's end. Happened when I really botched a shift, and rode with the chain in between gears for a lot longer than I should have (downtube shifters don't work well offroad).

It should be repairable, as soon as I can figure out how to get the upper pulley off.

Well, you only need 37T of Total Capacity, so it seems that Ultegra GS will be perfectly adequate. As for the Maximum Sprocket rating of 27T, that is a very conservative rating, it is sure to work with a 28T.

Cannondale made an Ultegra work on their triple, but they call it an "Ultegra Triple", which is probably some OEM-only or otherwise hard to find Ultegra SGS. Perhaps it is made specifically for Cannondale.

That $40 Cambriabike Ultegra RD-6500 will surely work, as long as it uses the same kind of attachment as your current derailleur. Then again, so would this $22 Deore SGS. (http://www.cambriabike.com/shopexd.asp?id=33426&page=SHIMANO+DEORE+RD-M510+SGS+REAR+DERAILLEUR)

The Deore SGS, having more capacity and being rated for a larger maximum sprocket, would let you use a wider range freewheel. With an SGS derailleur, you'd most likely be able to upgrade to a 7-speed freewheel like a 14-34 Megarange (http://harriscyclery.net/itemdetails.cfm?ID=778) if you wanted.

Nice price on the Ultegra. Thanks for that!

Also, you have 13-28 in the rear. What are your front chain rings sizes? My setup got a granny gear (50/45/28) so I may need more "Total Capacity". Thanks for you help.

My front triple is the Ultegra crankset - 52 -39-30. I also had it running on a front, cheap-Shimano-triple I replaced that was - 48-36-26. The Ultegra RD's seem to work on all road combinations commonly encountered. It's when you get into mountain-gearing, say 13 - 34, that it would need a mountain-bike RD. I'm also running an Ultegra on my vintage Puch with Campy Super Record 52-42 front and a Mich 8spd 12 - 25 rear.

Happy Trails!

My gearing "Total Capacity" would equal the Ultegra's "Total Capacity". My largest rear cog is one tooth over the "Maxium Sprocket" spec. Is that going to be a problem ?

Slack take up capacity, as you have already figured out, is adequate.

While the large cog capacity is 1 tooth outside of spec, that's a pretty conservative spec. Guys report exceeding that all the time so I doubt you'll have any difficulty. I suspect that Shimano's 27t maximum spec has more to do with Shimano road cassettes topping out at 27t.

Okay then, I will get either the Ultegra for the looks, or the Deore for long term upward compatibility. Thanks for the help. You guys rock!

I use an Ultegra GS on one of my mountain bikes. I like the polished finish and it works great.

The Ultegra RD mentioned from Cambria looks real nice.... it would fit right in on a vintage bike. I like that the printed "Shimano Ultegra" is understated.... unlike the mtb stuff . If you wanted it to look very retro, you could remove the Print using Brasso. I do this all the time with stems and such that have logos I'd rather not see. Brasso is a very mild metal polish, and preserves the anodized finish. On non anodized Al.... it makes stuff shine like a jewel :)

Don't worry about the product ID, as of course they are all imprinted with the model ## on the back.

I use paint stripper. It removes the painted logo instantly and has no effect on the anodizing.

To Jim: Thanks for the tip. I would like to keep the bike period correct. The orignal derailleur is a Sachs-Huret Duopar Eco. I'm on my second Duopar in less than a year so haven't had very good luck with them despite there high reputation. I'll check into the the Suntours. Thanks.
What has happened to them that you've decided to replace them?

What has happened to them that you've decided to replace them?

The chain frequently falls off the top derailleur pulley and wedges between the pulley and left cage plate. I am pedaling at the time this happens so the derailleur cage gets jerked hard. So I stop, put the chain back on the top pulley, straighten the cage out this best I can by eyeballing and continue on my way. The more this happens, the more the top pulley becomes worn from the chain scraping it when it is wedged, the more the cage becomes fatigued from twisting, and consequently the more likely this will happen again as a downward spiral.

From what I can tell, this happens after hitting a bump in the road that causes the chain to jump off the top pulley. The left side of the Duopar cage does not have much of a "guard" on that side to keep the chain from falling off that side. Also the top pulley has an unusually design, making a replacement almost impossible to find.

We prefer to keep the bike original and are actively looking for a replacement Duopar. But meanwhile the Ultegra will do fine based off the comments here. Thanks!

Thanks Dirtdrop and Garthr. Agreed and noted. Your comments are very helpful.

The chain frequently falls off the top derailleur pulley and wedges between the pulley and left cage plate. I am pedaling at the time this happens so the derailleur cage gets jerked hard.
Have you checked the alignment of the hanger tab?

I would also like to know if the sensation of drag that is experienced periodically on the 720 would be a result of the wear on the duopar derailleur. The drag feels like a sudden added weight or resistance on the rear of the bicycle, almost like the brakes are engaging but in actuality, they are not. Could this be added friction from the worn parts and slop in the components of the duopar? I love keeping the bike original and realize that the original derailleur has shown great service, but is just wearing out and that it might be a good idea to have a backup original and use a more replacable one for our extended touring miles. I ride this bike all the time and absolutely love it. It is so true! The Mrs.

Have you checked the alignment of the hanger tab?

No I haven't. Good idea though. I'll have my mechanic check it. Thanks.