# Mountain Cassette and R. Derailleur w/ Road STI shifters



## Grim Jones (Jun 17, 2010)

Hey all, I've searched and couldn't find the exact question/answer. If it's here, feel free to yell at me and point me in the right direction. If not, please lend a hand with an answer.

I'm running a 2008 Fuji Cross Comp with Shimano 105 STI's (2x10, but left is 3sp compatible), FSA 36-46t double crank, and ultegra 12-25 cassette, Ultegra rear derailleur.

The problem: I'm using the bike for commuting and touring and am getting ready to do some pretty serious elevations. I'm concerned that the gears just won't give me enough. Climbing is going to be difficult and going downhill I won't have that extra gear to give me that real kick. I'd like to have that "granny gear" to make uphills easier. Also, I'm spinning out going downhill and really would like to be able to really crank it out and get some serious speed.

The question: Can I switch the rear cassette to an 11-32 10 speed? I haven't seen any road cassettes with that ratio and in looking for mountain cassettes and derailleurs I'm finding the dyna-sys that isn't compatible (or so I've read) with my road shifters. 

I want to stay with my 2x10 setup. What can I do? Help me, please!


----------



## TomH (Oct 6, 2008)

a 46/12 combo will go 30mph at 100rpm.. At 30mph, you'd actually go faster going into a tuck and not pedaling. 

You can change your 36t ring to a 34t ring for more range. That, with a 27t cassette is a significantly lower gear. You should be able to use the shimano 10 speed mountain stuff, and and a shimano long cage road rear d, but id try the ring swap first.


----------



## Grim Jones (Jun 17, 2010)

Hmmm...that's an idea. I've seen some 12-28 road cassettes. That with the 34t ring could help. To be honest, though, I'm more concerned about the climbing than anything. I'm wondering how close that will get me. Thanks for the tip!

edit: the 12-28 isn't 10 speed. 12-27 it is then.


----------



## rloftus (Nov 21, 2006)

The SRAM 1050 cassette comes in an 11-32 version, and is 10 speed, and is compatible with your STI shifter. You would need a new derailleur to accommodate the wider gear range and larger cassette. The ideal choice would probably be the Shimano SLX RD-M662 derailleur in the shorter 'GS' version which has the capacity to handle your gear range with the 11-32, or most any other Shimano high-normal mountain unit would work.


----------



## TomH (Oct 6, 2008)

http://www.sheldonbrown.com/gears/

36/25 to 34/27 is a pretty good jump. You'll definitely feel it. 

Im a fatty with a 28 tooth cassette.. for the most part I can make it up most hills in my 39 tooth ring (triple). Going from a 25 to 28 tooth cassette was huge! The granny crank ring is almost useless with the 28 cassette.


----------



## Grim Jones (Jun 17, 2010)

TomH said:


> http://www.sheldonbrown.com/gears/
> 
> 36/25 to 34/27 is a pretty good jump. You'll definitely feel it.
> 
> Im a fatty with a 28 tooth cassette.. for the most part I can make it up most hills in my 39 tooth ring (triple). Going from a 25 to 28 tooth cassette was huge! The granny crank ring is almost useless with the 28 cassette.


Thanks, Tom! I think I'll take your advice and swap my ring to a 34. I did see the 11-28 Ultegra cassette. Will I need to make any adjustments to the cabling or derailleur with that setup?


----------



## Grim Jones (Jun 17, 2010)

rloftus said:


> The SRAM 1050 cassette comes in an 11-32 version, and is 10 speed, and is compatible with your STI shifter. You would need a new derailleur to accommodate the wider gear range and larger cassette. The ideal choice would probably be the Shimano SLX RD-M662 derailleur in the shorter 'GS' version which has the capacity to handle your gear range with the 11-32, or most any other Shimano high-normal mountain unit would work.


Ah! Missed this post. Thanks! That's certainly another option.


----------



## TomH (Oct 6, 2008)

That 1050 comes in a 28 tooth for 62 bucks too.. hell of a deal.

I, personally, like bigger gaps between cassettes. Most people dont. I like shifting to actually do something and find a big spread great. Its something to consider when buying though.


----------



## Grim Jones (Jun 17, 2010)

Hell, I may switch to the SRAM 1050 11-32 with a long cage RD, AND switch to a smaller 34 ring up front. That should give me all the gearing I could possibly want.


----------



## coachstevo (Sep 11, 2009)

Grim Jones said:


> Hell, I may switch to the SRAM 1050 11-32 with a long cage RD, AND switch to a smaller 34 ring up front. That should give me all the gearing I could possibly want.



I run a 34/32 on the really nasty climbing days-- wonderful to have the ultimate bailout gear. been doing it for ever now (5 years). FOr 10 speed you can go SRAM XX, Shimano XT 10, or now the road 11-32s.
You likely will NOT need to change your derailleur, just increase the B adjustment. I'm running an ultegra 6700 shortie, but have used 6600, 6500s as well.

With your "normal" derailleur you most likely won't be able to go to teh big ring and the 32, as you can't make the chain long enough to cover the 34/11, but certainly 54/28 is do-able.


----------



## charlox5 (Jan 31, 2011)

I run the SRAM 11-32 with a rival midcage rear derailleur and a compact double. 

has more range than my old triple + 12-27 setup and I like it very much.


----------



## Grim Jones (Jun 17, 2010)

Okay, so I ordered the SRAM pg1050 11-32 rear cassette. However, I have an Ultegra 6600 short cage rear derailleur. That apparently won't handle the setup. What rear derailleur will work? Keep in mind I'm running 105 brifters (2x10) and a 36-46 crank.

Help! I can't climb well and I spin out on the descents! ARRGH!


----------



## LongIslandTom (Apr 20, 2011)

I just did the swap on one of my bikes a few days ago and have ridden it a few times since. No problems.

The bike in question has a 50-34 compact double crankset, 12-25 10-speed cassette in the back, Ultegra derailleurs.

I replaced the rear Ultegra 6600 short cage derailleur with a new Ultegra 6700GS Medium Cage, put in the SRAM PG-1070 11-32T cassette, and a new 105 chain (it's heavier, but I've always had good luck with 105 chains so I'm sticking with it). The longer pulley cage on the medium-cage Ultegra 6700GS will have the capacity to take the longer chain to accomodate the biggest 32T rear cog.

The trick is to make sure you got the chain length right. If the chain is too short, when you accidentally crosschain big-big, it will lock up the drivetrain and damage the rear derailleur. So you need to make sure the chain is long enough to accomodate big-big crosschaining (big chainring front, big cassette cog back).

After getting the chain length right, you need to make sure the B-tension screw is adjusted so the rear derailleur pulley will clear the biggest 32T cog. Do a final adjustment on your derailleurs and you are ready to go.


----------



## Grim Jones (Jun 17, 2010)

LongIslandTom said:


> I just did the swap on one of my bikes a few days ago and have ridden it a few times since. No problems.
> 
> The bike in question has a 50-34 compact double crankset, 12-25 10-speed cassette in the back, Ultegra derailleurs.
> 
> ...


Thanks for the info. I was looking at the mountian derailleurs but could only find either 9 speed or dyna-sys. I guess I'll pick up the 6700 and have my LBS tune it up for me.


----------



## LongIslandTom (Apr 20, 2011)

Just keep in mind that there are TWO variants of the 6700 Ultegra rear derailleur. The 6700SS is the short cage version, and you don't want that. You need the medium-cage, which is the 6700GS.

I would also recommend getting a new chain if you already have more than 500 miles on your current chain. Even 500-mile chains would have developed a wear pattern meshing with the old cassette and a bit of chain stretch, which might cause chain-skip with a brand-new cassette.

I would encourage you to try the swap yourself. It's actually pretty straightforward if you have the tools (chain whip, lockring tool, adjustable hex wrench, chainbreaker tool, allen keys and screwdrivers). Good luck with your swap.


----------



## Grim Jones (Jun 17, 2010)

LongIslandTom said:


> Just keep in mind that there are TWO variants of the 6700 Ultegra rear derailleur. The 6700SS is the short cage version, and you don't want that. You need the medium-cage, which is the 6700GS.
> 
> I would also recommend getting a new chain if you already have more than 500 miles on your current chain. Even 500-mile chains would have developed a wear pattern meshing with the old cassette and a bit of chain stretch, which might cause chain-skip with a brand-new cassette.
> 
> I would encourage you to try the swap yourself. It's actually pretty straightforward if you have the tools (chain whip, lockring tool, adjustable hex wrench, chainbreaker tool, allen keys and screwdrivers). Good luck with your swap.


Thanks. I just found the right one for about $87 and free shipping. My chain has less than 500 miles on it. The bike's fairly new. Probably a little over 100 miles on it. 45 of them yesterday. I may do the swap myself. I'm fairly handy. If I run into an issue I can run it over to the shop where I bought it. They do free tune ups for a year and I ride with the owner on Friday mornings before work. It shouldn't be an issue.

I really appreciate the help. Cheers.


----------



## GFish (Apr 4, 2011)

I currently have the same gearing and considering making the same change for climbing. Except, I thought the Ultegra 6700GS was for a maximum 28T cog and the MTB RD-M771-SGS with a 34T maximum would work better with an 11-32 or even a 11-34 cassette. 

Is the Ultegra 6700GS really the right or best derailleur for the job? Also, is there any issue with cassette compatibility and would a Shimano XT M771 10-Speed cassette work better with a Shimano rear derailleur? 

I'm new to this, so still looking for more information, thanks. 



LongIslandTom said:


> I just did the swap on one of my bikes a few days ago and have ridden it a few times since. No problems.
> 
> The bike in question has a 50-34 compact double crankset, 12-25 10-speed cassette in the back, Ultegra derailleurs.
> 
> ...


----------



## LongIslandTom (Apr 20, 2011)

Hi GFish,

Yes, you can use an MTB derailleur if you wish, as long as it has the same cable pull ratio as your shifters.

Shimano does indeed recommend a conservative 28T maximum for its road derailleurs like the Ultegra. My guess on why would be that bigger cogs requires more B-tension to allow the pulley to clear the cog, and also the pulley cage needs to be extended very far forward to accomodate big-big crosschaining, both of which puts a lot of tension on the springs in the system. There seems to be enough headroom engineered into the derailleur to accomodate 32T, but now that I have done the swap and saw how much those springs had to strain, I wouldn't go above a 32T on the Ultegra 6700GS derailleur.

If you live in REALLY HILLY country and need a 34T cog on your road bike, then yes I'd go with an MTB derailleur that can accomodate that cassette size.


----------



## PJ352 (Dec 5, 2007)

LongIslandTom said:


> If you live in REALLY HILLY country and need a 34T cog on your road bike, then yes I'd go with an MTB derailleur that can accomodate that cassette size.


Since GFish mentioned having the same gearing as you (compact 50/34 crankset) I would also suggest he consider a triple.

Here's a gear calculator that may help:
http://sheldonbrown.com/gears/


----------



## GFish (Apr 4, 2011)

LongIslandTom said:


> Yes, you can use an MTB derailleur if you wish, as long as it has the same cable pull ratio as your shifters.


This is what concerns me most. I have 105 5600 STI and would like to avoid sloppy shifting. If going to a MTB derailleur creates poor shifting, I probably wouldn't make the change. How do you compare cable pull between shifters and derailleur's? 

I've been studying the gear calculator and noticed a lot of overlap when comparing compact vs triple. My current cassette is 12 - 25, changing this to an 11-28 would equal the lowest triple combination. I would still need to change the RD, since the short cage 105 won't cover a 28T. 

For now, I'm not in any hurry since all my rides are on mostly level roads. But I would like to go farther and that means a lot of climbing. So at some point, I'd like to change the gearing.


----------



## Grim Jones (Jun 17, 2010)

So, is the Ultegra 6700gs going to give me problems? I can always send it back, I suppose. I was trying to avoid the MTB derailleur because of the cable pull issue and the fact that anything decent in a 10 speed seems to be dyna-sys which isn't compatible with my shifters.


----------



## LongIslandTom (Apr 20, 2011)

No, no problems with the 6700GS. There is still some room to spare in the derailleur's range of motion after I put in the 11-32T. I just wouldn't use any cassettes larger than that with the 6700GS.


----------



## Grim Jones (Jun 17, 2010)

LongIslandTom said:


> No, no problems with the 6700GS. There is still some room to spare in the derailleur's range of motion after I put in the 11-32T. I just wouldn't use any cassettes larger than that with the 6700GS.


Yeah, I just did a search and it seems a lot of people are running this setup. It'll be nice to be able to climb a bit easier.


----------



## LongIslandTom (Apr 20, 2011)

GFish said:


> I've been studying the gear calculator and noticed a lot of overlap when comparing compact vs triple. My current cassette is 12 - 25, changing this to an 11-28 would equal the lowest triple combination. I would still need to change the RD, since the short cage 105 won't cover a 28T.


GFish, the 11-28T will work with your 105 short cage rear derailleur. The 105 short cage has a published cog capacity of 27T for the 5600SS, and 28T for the 5700SS. The 5600SS 27T is a conservative figure. Just one more tooth on the biggest cog will not come anywhere near maxing out the derailleur's range of motion, which is engineered with some headroom.

Throw on that 11-28T (and a new chain if you had more than 500 miles on the existing chain) and enjoy your hill climbs.


----------



## PJ352 (Dec 5, 2007)

GFish said:


> I've been studying the gear calculator and noticed a lot of overlap when comparing compact vs triple. My current cassette is 12 - 25, changing this to an 11-28 would equal the lowest triple combination. I would still need to change the RD, since the short cage 105 won't cover a 28T.


Since compacts offer a (good) compromise between std doubles and triples,overlaps are a given, but I disagree that going to a 28T (with your 34T inner ring) equals the lowest triple combo with a ~30T inner ring. It's lower by 14.3%, but that might not be worth the cost unless you also changed out the RD to accommodate a 32 or 34T cog. 

Also, a SS RD will work with a 28T cog, but you have to also watch the total tooth capacity.


----------



## GFish (Apr 4, 2011)

PJ352 said:


> I disagree that going to a 28T (with your 34T inner ring) equals the lowest triple combo with a ~30T inner ring. It's lower by 14.3%


That depends on the cassette. I see some triples have a 12-25 and others have an 11-28. To match the 11-28 with a triple, I would need the 11-32 with a compact 50/34. At least if I'm reading the chart correctly. 

What about the cable pull with 5600 105's? Can I change to a MTB RD without affecting the shifting? 

Honestly though, I really don't know how low I need, but I plan to find out soon enough. 

Thanks for the help.


----------



## PJ352 (Dec 5, 2007)

GFish said:


> *That depends on the cassette*. I see some triples have a 12-25 and others have an 11-28. To match the 11-28 with a triple, I would need the 11-32 with a compact 50/34. At least if I'm reading the chart correctly.
> 
> What about the cable pull with 5600 105's? Can I change to a MTB RD without affecting the shifting?
> 
> ...


Yes, of course it does. In my example I compared a 34/ 28 combo with a 30/ 28 and the latter is 14.3% lower. My mention of a triple was simply that it was an option, but cost-wise trying the cassette swap first makes the most sense.

Sorry, I can't answer your MTB RD cable pull question. I'm strictly a 'roadie'.


----------



## a_avery007 (Jul 1, 2008)

run a mtb rear der. and you can run an 11-34t rear cassette. (no triple needed)

hope this helps


----------



## Ngehe (Mar 29, 2011)

I actually had your problem not too long ago. Whatever crankset you have does not matter as long as you have the correct chain length. Simply get new chains for the new setup.

The real issue is the RD. I put a 10-speed XT cassette (11-36) on the rear wheel along with a 10-speed XT RD. It did not work. The Ultegra STI could not pull enough cable to shift to the lowest gear.

However, the RD is basically a dumb unit as there is no indexing on the actual RD — all indexing is done on the shifter. I changed out the 10-speed XT RD to an older 9-speed, and voila!, it worked perfectly. The difference between the 10- and 9-speed RD is the length of the arm anchoring the cable to the RD. The shorter arm of the 9-speed XT RD allowed for greater mechanical advantage to pull enough of the cage to the lowest gear.

Another small issue is the length of cable from the shifter to the RD. Road RD require a loop from the chainstay around to the anchor of the RD. MTB RD goes straight from the stay to the anchor. Switching from Road to MTB RD will be not problem, but if you decide to cut off the cable for MTB, you may not have enough to switch back to Road.


----------



## GFish (Apr 4, 2011)

Ngehe said:


> I changed out the 10-speed XT RD to an older 9-speed, and voila!, it worked perfectly. The difference between the 10- and 9-speed RD is the length of the arm anchoring the cable to the RD. The shorter arm of the 9-speed XT RD allowed for greater mechanical advantage to pull enough of the cage to the lowest gear..


Specifically, which RD model number and does Shimano sell this RD currently?


----------



## Ngehe (Mar 29, 2011)

GFish said:


> Specifically, which RD model number and does Shimano sell this RD currently?


I believe any 9-speed RD should work. The one I used specifically is a pre-Dynasys Shadow XT, RD-M772-SGS. I believe Shimano still sells them.


----------

