# 12/30 cassette with an Ultegra Short Cage RD..any issues?



## butzdogg (Sep 16, 2002)

According to Harris Cyclery and their website, theyare compatible. IS anyone running this set-up? Do any mods need to be made, such as shortening the RD cable housing? feedback is much appreciated as I am cosnidering this set-up for a hill climb race next weekend


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## everythingeverywhere (Oct 13, 2007)

i use a 9spd 105 rd with a 12-30 cassette and it works fine. the 30 is practically my secret weapon on steep climbs when others don't have proper gearing. they're standing and struggling and i'm sitting and spinning. hehe. 

but really, 12-27 is stock and is so similar to a 12-30...


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## Dr_John (Oct 11, 2005)

> i use a 9spd 105 rd with a 12-30 cassette and it works fine.


With a short-cage derailleur?


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## cyclust (Sep 8, 2004)

I run a 34-50 compact with a 12-27 rear and my shifting improved after I switched to a long cage derailleur. The short cage will handle it, but it maxes out the capacity.


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## Dr_John (Oct 11, 2005)

> I run a 34-50 compact with a 12-27 rear


I do too with a short cage, and I think the shifting is fine, even though it exceeds the Shimano recommended chain wrap length capacity by two. It's a very common configuration. And Specialized now uses a SRAM 11-28 cassette/Shimano short-cage on some of their bikes, which I thought would have to be the practical limit.


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## yakobo (Aug 22, 2006)

I use this setup (Ultegra 9speed short RD with a 30t) successfully with either a 39-53 or 34-50 up front, having first read about it when looking into Harris Cyclery's Century Special (13-30), which they say will work with any RD. I ended up just adding a 30t flat sprocket to a 12-27 cassette, removing the little used 13t when I put the hill buster 30t on to go to the mountains. Trying to fix a friend up with the a 30t using a longer deraileur cage I had trouble keeping the pulley from hitting the cassette cogs, even with the b screw fully screwed in. Not sure if it just works better with a shorter RD or what. Maybe someone else can answer this.


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## PeanutButterBreath (Dec 4, 2005)

The dimensions of the derailleur hangers are the likely cause of the differing results.

The cage length of a RD determines the amount of chain slack that it can take up. If you are running a 53T in the front and enough chain for a 30T in the rear (just to be on the safe side, since you shouldn't ride that combo), you are going to have a lot of slack at the opposite end of the spectrum (small chainring, smaller cogs).

The maxium sixe cog that an RD can shift to has nothing to do with the cage length.


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## ericm979 (Jun 26, 2005)

The solo flat sprocket will only work with 9sp, not 10speed.

A 50/34 and 12-27 is already beyond Shimano's chain wrap spec. A 12-30 and 50/34 will be too far past it. You won't be able to use the smallest 2-3 cogs without the chain sagging or rubbing on itself unless you set the chain length so short that if you accidentally shift into the 50x30 combo it will be too short and destroy the derailleur or chain hanger. I don't recommend that. It's too easy to make a mistake like that in a climbing race.

I'd get the "triple" rear derailleur so there's no worry. It's only about 20 grams extra.


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## DaveT (Feb 12, 2004)

ericm979 said:


> The solo flat sprocket will only work with 9sp, not 10speed.
> 
> A 50/34 and 12-27 is already beyond Shimano's chain wrap spec. A 12-30 and 50/34 will be too far past it. You won't be able to use the smallest 2-3 cogs without the chain sagging or rubbing on itself unless you set the chain length so short that if you accidentally shift into the 50x30 combo it will be too short and destroy the derailleur or chain hanger. I don't recommend that. It's too easy to make a mistake like that in a climbing race.
> 
> I'd get the "triple" rear derailleur so there's no worry. It's only about 20 grams extra.


I agree. I"m running a 50/34 compact with an IRD 11/30 cassette and was required to use a triple rear derailleur so I could use all of my rear cogs when in the big ring.


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## txn (Apr 4, 2006)

yakobo said:


> I ended up just adding a 30t flat sprocket to a 12-27 cassette, removing the little used 13t when I put the hill buster 30t on to go to the mountains. QUOTE]
> 
> What 30t sprocket did you use?


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## yakobo (Aug 22, 2006)

Nine speed flat sprockets available from Harris at: http://harriscyclery.net/itemdetails.cfm?ID=800

Some bigger 10 speed sprockets now available from Miche.

My bad. It is true with a 12-30 on the back and 50-34 up front one will have to deal with a chain too loose to use the smaller cogs in back, but then I just use this setup for big mountain rides and don't use those combinations . Yes, a triple RD would be a solution if one wants things to work all the way around. I do use the 50-30 combination some w/o problems. Comes in handy at the crests of short hills.


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## kneejerk (Feb 2, 2007)

pushing the limits of what a short derailer can handle for sure with a normal 2 ring crank setup,

going with a medium caged rear derailer doesn't reduce the efficiency of the system, it adds a few chain links and minor weight, the medium caged derailer may actually increase the efficiency compared to an overly stretched small cage,


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## esenkay (Jan 1, 2006)

After talking to the man himself (the late great Sheldon Brown) I used a 13-30 custom cassette from Harris Cyclery with a 53/39 up front for the 2006 Etape. 
This was a 9 speed set-up with a short cage Ultegra rear derailleur....no modifications were needed and no problems whatsoever.


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