Help With Shimano Ultegra 11 Speed Di2 Rear Derailleur & 11/32t Cassette

[grecinos]

Hey guys,

I'm going to upgrade my current 10 Speed Ultegra Di2 Componentry to 11 Speed Ultegra Di2. My rationale is that I would like to have an 11/32T rear cassette, I currently have an 11/28T. My question is, what is the difference between a GS and an SS Cage?

Will this derailleur work with 11/32T?

http://www.performancebike.com/bikes/ProductDisplay?langId=-1&storeId=10052&catalogId=10551&productId=1158245&summaryOnly=true&quantity=1

TIA,

grecinos

 

[CAMPYBOB]

http://bike.shimano.com/content/sac-bike/en/home/components11/road/ultegra-di21/rd-6870-gs.html

The GS Long Cage version will handle a 11-32 cassette and wrap a maximum of 37T.

http://bike.shimano.com/content/sac-bike/en/home/components11/road/ultegra-di21/rd-6870-ss.html

The SS Short Cage version will handle an 11-28 cassette and wrap a maximum of 33T.

No, the SS version from Performance Bike that you referenced will not handle a 32T cassette.

 

[grecinos]

Thanks for the response.

Something doesn't correspond correctly. Take a look at the photo from my link. It corresponds to the first link (GS Long Cage) you provided. However, the overview from Performance Bike says "Short cage design". I think I'm going to hold off on the purchase and ask their techies tomorrow.

 

[alfeng]

Hey guys,

I'm going to upgrade my current 10 Speed Ultegra Di2 Componentry to 11 Speed Ultegra Di2. My rationale is that I would like to have an 11/32T rear cassette, I currently have an 11/28T. My question is, what is the difference between a GS and an SS Cage?

Will this derailleur work with 11/32T?

http://www.performancebike.com/bikes/ProductDisplay?langId=-1&storeId=10052&catalogId=10551&productId=1158245&summaryOnly=true&quantity=1

FWIW. Most-if-not-all of Shimano's Road & MTB mechanical rear derailleurs can actually handle the 32t Cog on most of the frames produced after 1998 ...

EITHER by making an adjustment to the B-screw on the rear OR by swapping the 11t upper jockey wheel with a 10t jockey wheel ...

BUT, as CAMPYBOB infers, the SS cage rear derailleurs will not be able to handle the amount of chain that you will need IF the chain is long enough to preclude a potential disaster if you were to have the chain on the Large-Large Chainring & rear Cog combination ...

UNLESS you are willing to have a slack lower chain when using the combination which includes the inner Chainring + some of the smaller Cogs ...

With a MTB, you are inviting disaster when the lower portion of the chain is slack ...

With a ROAD bike, a slack lower chain is mostly a cosmetic issue.

I do NOT know what the difference is between the 10-speed & 11-speed mechanisms may-or-may-not be ...

FYI. The cages on most Shimano's 9-speed and 10-speed MECHANICAL rear derailleurs are interchangeable ...

IF the cages on the Di2 rear derailleurs are connected the same way, then you can replace the SS cage on your current rear derailleur with one from almost any other Shimano Road or MTB rear derailleur ...

It's not very difficult UNLESS you have zero-or-limited manual skills.

I do NOT know if any 11-speed Di2 rear derailleur is compatible with 10-speed Di2 shifters, and vice versa ...

If you plan to buy a NEW rear derailleur, then you may want to inquire about the feasibility of using an XTR DI2/electronic rear derailleur with your Ultegra Di2 shifters to ensure maximum drivetrain configuration flexibility ...

Or, simply consider a "Compact" crankset + GS Di2 Road rear derailleur.

BTW. If you simply want a 32t Cog, then you don't need an 11-speed Cassette/etc.

 

[alfeng]

BTW. The point is that you could possibly cannibalize a mechanical Shimano rear derailleur for a longer cage which you may-or-may-not be able to graft onto your current Di2 rear derailleur.

 

[grecinos]

BTW. The point is that you could possibly cannibalize a mechanical Shimano rear derailleur for a longer cage which you may-or-may-not be able to graft onto your current Di2 rear derailleur.

Hehe. Sounds interesting and might be a fun challenge. But, I think I'm going to take the easy route and purchase the components that were designed specifically for my needs. If I start tinkering around, it might void the warranty and I wouldn't be able to return any purchased components. Plus, there's no telling how well the mods will hold up. I usually purchase from Performance Bike and Nashbar because they have price matching and you can return merchandise for a refund/credit even if you had the item for over a year. But the merchandise has to be in good condition to get a full refund, otherwise you only get partial. Tinkering would no doubt void this policy.

 

[swampy1970]

Hey guys,

I'm going to upgrade my current 10 Speed Ultegra Di2 Componentry to 11 Speed Ultegra Di2. My rationale is that I would like to have an 11/32T rear cassette, I currently have an 11/28T. My question is, what is the difference between a GS and an SS Cage?

Will this derailleur work with 11/32T?

http://www.performancebike.com/bikes/ProductDisplay?langId=-1&storeId=10052&catalogId=10551&productId=1158245&summaryOnly=true&quantity=1

TIA,

grecinos

Do you really have a need to use a 32?

 

[grecinos]

Do you really have a need to use a 32?

Yes. I live out in the country and there are mountains with gradients reaching 10%. With a 28T, I find myself out of the saddle half the time on this type of terrain. With a 32T, I should find it easier to stay in the saddle.

 

[grecinos]

An update:

I received all of the new components on Wednesday and finished installing it on Thursday. I've ridden twice since then. I'm still dialing in the settings. The results are promising. I was able to use the 32T today. It was somewhat awkward. I normally use my 28T on this climb, having that extra gear helped while in the saddle. I was still in and out of the saddle, but this was a welcome improvement.

I did run into a snag while installing the front derailleur. There is a support bolt (on the front derailleur) that is supposed to rest on the support plate (on the bike frame). The problem is, there is no support plate on my frame. I've contacted Trek via email and have yet to receive a response. If anyone has a suggestion, I'd greatly appreciate it. On the positive side, it doesn't appear to hinder the functionality of the derailleur, but no telling what will happen later down the road.

 

[oldbobcat]

I did run into a snag while installing the front derailleur. There is a support bolt (on the front derailleur) that is supposed to rest on the support plate (on the bike frame). The problem is, there is no support plate on my frame. I've contacted Trek via email and have yet to receive a response. If anyone has a suggestion, I'd greatly appreciate it. On the positive side, it doesn't appear to hinder the functionality of the derailleur, but no telling what will happen later down the road.

Yes. The backing plate is a derailleur component, not a frame component, so you would have more success contacting Shimano. Or you could call a couple of your local shops and see if they could spare you one. They come in a pack of two, a flat one and a curved one. Trek road frames have ovid seat tubes, so use the curved one.

Trek front derailleur mounting tabs are stiff and attached to a very stiff, and the base of the seat tube is stiff and possibly a little over-built. That's a good thing. I've seen some tabs attached to carbon tubing so thin the tab moves with every shift to the big ring. You can imagine what could happen to the frame if something got stuck.

If the bike is shifting fine, I wouldn't stop using it, but I'd install the reinforcement plate ASAP, if only to keep the warranties valid. They're not hard to get.

 

[grecinos]

Yes. The backing plate is a derailleur component, not a frame component, so you would have more success contacting Shimano. Or you could call a couple of your local shops and see if they could spare you one. They come in a pack of two, a flat one and a curved one. Trek road frames have ovid seat tubes, so use the curved one.

Trek front derailleur mounting tabs are stiff and attached to a very stiff, and the base of the seat tube is stiff and possibly a little over-built. That's a good thing. I've seen some tabs attached to carbon tubing so thin the tab moves with every shift to the big ring. You can imagine what could happen to the frame if something got stuck.

If the bike is shifting fine, I wouldn't stop using it, but I'd install the reinforcement plate ASAP, if only to keep the warranties valid. They're not hard to get.

Thanks for the response. That's exactly what I needed to know. I'm going to make some calls ASAP as per your suggestion.

Thanks.

 

[grecinos]

Update:

I called a local bike shop and inquired about the support/backing plate. The guy I spoke with knew exactly what I needed. He said the plate has a sticky back that adheres to the frame. Is that what is normally used?

FYI: I live about 1 hour away from his shop and asked if he could mail it to me, he said yes. (Of course I have to pay for it, no problems there).

 

[oldbobcat]

Yep, that's the one.

Here's a link to the dealer manual for the front derailleur: http://si.shimano.com/php/download.php?file=pdf/dm/DM-UL0001-02-ENG.pdf

Page 22 shows the placement of the plate.

 

[grecinos]

Yep, that's the one.

Here's a link to the dealer manual for the front derailleur: http://si.shimano.com/php/download.php?file=pdf/dm/DM-UL0001-02-ENG.pdf

Page 22 shows the placement of the plate.

Excellent. Thanks for that bit of info.