# Shimano 105 wider range gearing



## Stogaguy (Feb 11, 2006)

My girlfriend has a Trek Madone 3.1 with Shimano 105 (5700) and wants a lower gear for long/steep climbs. I am writing to ask what Shimano rear derailleur I should use for this project.

Current set-up: 
Shifters: ST-5700
Front Derailleur: FD-5700
Rear Derailleur: RD-5700SS
Crank: Sram Apex 34/50
Cassette: CS-5700 11-28
Chain: KMC X10SL

Want to go to:
Shifters: ST-5700
Front Derailleur: FD-5700
Rear Derailleur: TBD
Crank: Sram Apex 34/50
Cassette: Sram PG-1050 12-32
Chain: KMC X10SL (but longer)

Bottom line, I plan on changing the chain, cassette and rear derailleur. My question is, what rear derailleur should I use?

I have a similar conversion on two of my bikes and have used a Shimano Deore XT RD-M771 GS rear derailleur. This has worked pretty well, but the shifting has never been as precise as the short cage road derailleur with a tighter cassette. I am wondering if there is anything better.

Thank you in advance for your help. I look forward to your thoughts.


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## victorscp (Nov 8, 2011)

i would just go with the sram apex rear deraileur mid cage


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## Stogaguy (Feb 11, 2006)

*Different cable pull per shift?*

victorscp, thank you for your reply. While I am more than willing to stand corrected on this point, I do not think that Sram derailleurs are compatible with Shimano shifters. While the spacing between cogs on Shimano and Sram cassettes is the same, the cable pull required per shift with their derailleurs is not. 

Can anyone chime in with a definitive answer on the cross compatibility of Shimano shifters and Sram derailleurs?


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## gp3d (Jul 6, 2011)

I wonder if the Ultegra rd-6700-gs rear derailleur would shift better than the Deore?


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## fun2none (Mar 16, 2010)

I used a Shimano *9-speed* RD-M592 rear derailleur to shift a SRAM PG1050 11-32 cassette via ST-5700 shifters. It works like a charm. *Shimano road shifters will not work with a SRAM rear derailleur or Shimano Dynasys 10sp mtb rear derailleur*.


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## MySpokeIsABroke (Sep 24, 2011)

Apologize in advance for not directly answering the question. But I wonder about the overall gearing and goal asI find my gearing to high, too closely spaced, and too not suited for my riding ( Sora triple). Wouldn't a chainring of 24 or 28 in lieu of the 30 be more of a gear change than the cassette change of 12-32 to 11-28 ???


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## Trek2.3 (Sep 13, 2009)

To go to 32 you don't have to change the RD. Only for 34 or larger. I've done this on my Trek 1.5 that I leave in Europe.


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## tihsepa (Nov 27, 2008)

I agree with Trek 2.3. You can run a 32 with a 5700 rear mech.


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## Stogaguy (Feb 11, 2006)

*SS or GS cage?*

Does this really work with the RD-5700SS or is the GS cage required? If the SS works, I will give this try. Interesting, because both the cog size and total wrap in this set-up is greater than Shimano specified maximums for the SS model. Shimano's spec's:

SS cage: capacity = 33 teeth, max cog = 28 teeth
GS cage: capacity = 39 teeth, max cog = 28 teeth

34/50 coupled with a 12-32 equates a 36 tooth capacity requirement.


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## tihsepa (Nov 27, 2008)

I bet you could do it with the SS. I would try it. Set your chain up big big and make sure it has tension in small small and run it.


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## Kerry Irons (Feb 25, 2002)

*Another approach*



tihsepa said:


> I bet you could do it with the SS. I would try it. Set your chain up big big and make sure it has tension in small small and run it.


If the RD doesn't have enough tension in the small-small combo, you could also just let that go since that is a cross chain situation that shouldn't be used. Most likely it couldn't be used because the chain would be scraping against the big chainring. I ran a wide range triple on a tandem with a stanard road deraileur and I just knew to never use the smaller cogs when I was in the granny.


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## AndrwSwitch (May 28, 2009)

I would start by just swapping in the new cassette and chain, same as others are suggesting. I've found that both the max. cog and max. wrap specs are a little conservative on Shimano derailleurs.

If you do need a MTB derailleur, it's not like you need to replace your chain and cassette again. So it's a little extra trouble, but no double-buys on gear. (Same with the GS. You can probably get a decent read on the situation by seeing if the B screw gets the SS derailleur to clear the 32t cog.)

I'm comfortable with the idea of a chain that's sometimes slack, but not with one that won't fit over big/big. While I like to see myself as smart, I sometimes do dumb things. I'd rather not have that mean I break my chain.

MySpoke: just do the math. I usually use Google Search because I'm too lazy to open Excel. Sheldon Brown's site also has a good gear calculator. If you change your smallest chain ring, you should think about what it will do to your shift patterns, and whether that's acceptable to you. You might also consider a compact triple, with a 110/74 bolt pattern, as an alternative. You can size your middle and big rings for a less drastic shift. velo-orange.com has some stuff like this in stock.


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## redlude97 (Jun 29, 2010)

Consider the new tiagra 12-30 cassette as well


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## Phredly (May 2, 2012)

I'm a heavy, old newbie and quickly realized I would need some help with long hills. I have a 105 5600 triple with 27 tooth max and I changed to 5700A GS which has a stated 30 tooth max and a 12-32 1070 sram cassette and it works like a charm. You may or may not need a longer B screw, to allow the top idler cog in the derailleur to clear the cassette cogs but this depends on the shape and length of your hanger. Longer B screws or bolts are readily available. I needed the GS to wrap the chain on the triple, but a short cage should work for the double.


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## Stogaguy (Feb 11, 2006)

*Thanks everyone*

Thank you all for your replies. Based on this discussion, I will simply change the cassette and chain and try it with the current RD-5700SS rear derailleur. If that works, project finished. If no, I will pick a new derailleur based on what I see relative to the chain tension and b-screw considerations.

In any event, I will report back on the results.


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## Mnkykng77 (May 7, 2012)

Stogaguy said:


> Thank you all for your replies. Based on this discussion, I will simply change the cassette and chain and try it with the current RD-5700SS rear derailleur. If that works, project finished. If no, I will pick a new derailleur based on what I see relative to the chain tension and b-screw considerations.
> 
> In any event, I will report back on the results.


ANy up date as to how this is going? I am debating if I want to change my rear cassette to the Tiagra 12-30 as I need more "help" getting up the steep hills and would like to have that 30T cog.


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## Stogaguy (Feb 11, 2006)

*In process*

I have determined:

1. My GF's derailleur is the RD-5700 SS as opposed to the RD-5700A SS.
2. The RD-5700 SS will easily clear the 32T cog , but does not produce sufficient tension in the small-small combination. I tried by swapping in my wheel with the 11-32.

I picked up a RD-5600 GS on eBay and am waiting for it to arrive. I will post an update when I actually do the conversion and it has been road tested.


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## Stogaguy (Feb 11, 2006)

*Final solution*

I am writing with an update on this project. The gearing conversion is finsihed and road tested. Everything is working well and the shifting is pretty crisp. Went with the following:

Rear Derailleur: RD-5600 GS
Cassette: Sram PG-1070 12-32
Chain: Sram PC-1051

The chain is sized per Shimano's reccomendations (cage perpendicular to the ground in high gear). I did have to install a longer B-screw to get the guide pulley to clear the 32T cog when on the small chainring. The bike will shift into and out of the "big-big" without hesitation. This makes the set-up pretty fool-proof. 

I started with the chain sized using the "little-little" method, but (interestingly) I could not get the guide pulley to clear the 32 in the lowest gear. I shortend the chain two links at a time and kept playing with the adjustments. The final lenght (Shimano's reccommendation) is six links shorter than the lenght I started with ("little-little" method). I would prefered a slightly longer chain but just could not get it to work right.

Here are a few pictures of the new set-up. You can see in the close up of the B-Screw that there is barely enough shoulder on the derailleur hanger to accommodate the longer screw.


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## MikeWMass (Oct 15, 2011)

You can always bend the b screw once you get it where you need it so it will contact the shoulder on the hanger. I have an old french frame with Simplex dropouts, which did not use shoulders. I had to file in a shoulder, and then bend the screw in order to use a non-Simplex derailleur, works fine.


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## Stogaguy (Feb 11, 2006)

*Simple and effective*

I salute you for rehabilitating an old French frame. My first race bike was a Gitaine Tour de France circa 1972; Mafac brakes, Stronglight cranks, Simplex shifters the whole nine yards... The old French stuff had its charms, but was a pain because of the lack of compatibility with the rest of the world.

I like the bending the B-screw idea, simple and effective. However, I would be worried about getting it out if I ever need to. My "plan B" was to flip the screw so the head would be against the shoulder. I would have cut a slot in the other end with a Dremel to be able to adjust it with a straight blade screw driver.


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