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Discussion Starter · #1 ·
I am looking to purchase a 30T Shimano rear cog (NOT chain ring) to convert my 10 speed triple with a 12-27 road cassette to a 12-30.

I once talked to a guy who had a 12-27 Shimano cassette and removed the 16T cog and added the 30T cog and was able to keep the same rear derailleur and chain length.

The existing cassette is a Shimano Ultegra 12-27 road cassette.

Can anyone help me find a single 30T Shimano cog compatible with this cassette?

Thanks,
Bornin53
 

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You can't do that with 10sp. The last (largest) cog needs to be offset or dished, and Shimano doesn't make single cogs like that. I don't know of any current 10sp 30t solution.

Your rear gearing options are a 12- or 11-28 IRD cassette, or a 12- or 11-32 IRD. The latter may require a mountain bike rear derailleur.... a road triple RD may work even though it's over spec by quite a ways.

Possibly a better way would be to get a smaller small chainring. If you still have the 30t, a 28 or 26t should work on 105 and Ultegra. DA uses a special Shimano-only BCD for their triple and only 30t rings are available for it.
 

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bornin53 said:
I am looking to purchase a 30T Shimano rear cog (NOT chain ring) to convert my 10 speed triple with a 12-27 road cassette to a 12-30.

I once talked to a guy who had a 12-27 Shimano cassette and removed the 16T cog and added the 30T cog and was able to keep the same rear dérailleur and chain length.

The existing cassette is a Shimano Ultegra 12-27 road cassette.

Can anyone help me find a single 30T Shimano cog compatible with this cassette?

Thanks,
Bornin53
Might as well go all the way and get an MTB cassette. 12-32. Get yourself an XT rear dérailleur and you're set.
 

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ericm979 said:
You can't do that with 10sp. The last (largest) cog needs to be offset or dished, and Shimano doesn't make single cogs like that. I don't know of any current 10sp 30t solution.

Your rear gearing options are a 12- or 11-28 IRD cassette, or a 12- or 11-32 IRD. The latter may require a mountain bike rear derailleur.... a road triple RD may work even though it's over spec by quite a ways.

Possibly a better way would be to get a smaller small chainring. If you still have the 30t, a 28 or 26t should work on 105 and Ultegra. DA uses a special Shimano-only BCD for their triple and only 30t rings are available for it.

Both Contador and Hondo ran a 34-30 for today's stage in the Giro. I cannot imagine they are not using 10 spd. stuff.

I have no clue what to buy or how to set it up, but I suspect it can be done if they are any indication...

ZAch
 

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Discussion Starter · #8 ·
Ken:

Thanks. This is what I was looking for. I appreciate the suggestion of the 12-32 MTB cassette, and derailleur, but I'd prefer to have a spare wheel with the 12-30 cassette and use it only when there are extreme climbs on the route.
 

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Another alternative is the IRD 11-30 10-speed Shimano compatible cassette. It's a fairly new item and not listed on IRD's website yet. I've got one and use it with a 34-50 compact crank set.
 

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I think that Sram has a 12-30 or 11-30 cassette announced but not yet available to the general public. Since Astana's on Sram, that's probably what they used.

That Aviotek is a Miche, and I'm not sure it's available in the US, or that it has the same spacing to work correctly with Shimano cogs.

CycleDynamics used to make custom ti cogsets up to 30t but they seem to have stopped answering the phone.
 

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Discussion Starter · #13 ·
Here's Where I am at.........

First off, I appreciate ALL of the advice received.

Let me first state my "requirements". The club rides I go on are in the Santa Cruz mountains in Northern CA. 100% of my miles are road miles. Maybe once a year I'll go to the Sierra Nevada mountains near Lake Tahoe. The typical ride is 80 - 100 miles with an elevation gain of 7,000 - 11,000 feet.

I have a DA 52/39/30 triple and a 12/27 10 speed cassette. I just switched to an Ultegra cassette for durability. Its pretty rare that I wish I had a lower gear, but about 2 - 3 times per year, the Saturday ride will on a diabolical route with extended grades approaching and occasionally exceeding 20%, where I am out of the saddle for as much as a half mile at a time (worst case example).

For these rides, I would like to be able to just pop on a spare wheel with lower gears, make a B screw adjustment and not have to worry about chain length or a different rear derailleur. I do understand I have to be careful not crosschain and go big/big.

Another guy in the club has a Shimano 9 speed 12/27, but he removed the 15T cog and put a 30Tcog in the last position. If I recall correctly, the 30T cog was flat, not dished, but that was a 9 speed and I am seeking to do the same with a 10 speed.

A question I would like the answer to is whether I can take an Ultegra 12/27, remove the 16T cog and put the Marchisio Aviotek 30T Shimano 10 spd compatible cog (see photo in Ken's first post above) in the last position. Earlier ericm979 said the last cog has to be offset or dished. The Marchisio in Ken's photo certainly looks dished to me. Still, ericm979's not sure the spacing would be right. I emailed this question to Parker International and to http://clemenzo.com, but have not received a reply yet.

Since I already have a spare 12/27 Ultegra cassette, the above solution would cost me $28 plus international shipping.

If the answer to the above question is "No" (or nobody knows for sure) the the next cheapest/least hassle route would appear to be purchasing an fill 11/30 or 12/30 SRAM, IRD or Miche cassette. Either of these options would meet my requirements, its just a matter of cost.

Dave - You said you have the IRD 11-30 10-speed Shimano compatible cassette. Do you know where I can get one and what the price is? Does anyboy else know where I can get a 12/30 or 11/30 Shimano compatible 10 spd cassette at a reasonable price?

Thanks to all !!
 

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If the spacing's not close enough (there is some lattitude) you may be able to make up a spacer using some Shimano 1mm 10sp spacers and some of those thinner shims that used to come with 9sp cassettes or certain wheels (I can't remember where I got them, but the LBS should have them). I'd try it. You'd only be out $28 plus shipping if it doesn't work.

One thing I forgot to mention is that you'd better have a steel or Ti freehub body if you want to run a large solo cog. It'll eat up an aluminum freehub, especially a 9sp style freehub with the shallow splines.

9sp doesn't need a dished large cog. I've built custom 9sp cassettes exactly the way you're wanting to do, using a solo cog from Harris Cyclery.


Any decent shop should be able to order IRD stuff. Spokesman in santa cruz or cupertino bikes should do.

Where's the diabiolical 20%er? I'm in the SC mountains.
 

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I also ride in the mountains from Palo Alto to Santa Cruz and set my Dura Ace up with a 12-27 on the back but with an Ultegra triple up front. The 30 inner ring was replaced with a 28 by Salsa. We had to go with the Ultegra crank so that the bolt patterns would line up.

The shifting is perfect. It is nice for those occasional 17% grades to have the extra gear.

My other bike uses Campy Chorus and I had the LBS combine a 13-29 with an 11-25 to get an 11-29. This gives the same low gearing as the above Shimano but there is one difficult shift where the combination occurred. It is not a major problem because it appears when going faster and the shifting does not have to be as precise.
 

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Will the following setup work?

I ride a lot of mountains and currently am running a triple crankset. I want to switch to double.

Bottom line. . . will the following set up work on my road bike?

50/34 compact crankset; 12/30 -10sp cassette; medium cage (7800-GS) dura ace rear derailleur; dura ace 7800FD front derailleur.


Next, how about using a short cage rear derailleur such as Dura ace 7900-SS?
 

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I ride a lot of mountains. I currently ride a triple drivetrain. I am building a new Parlee z2 and want to switch to a double ring setup.

Bottom line. . . Will the following setup work without to much chain slap?

Compact double 50/34 crankset; 12-30 - 10sp cassette; Medium cage dura ace 7800GS derailleur.

Next:
Same as above except use a dura ace 7900SS derailleur.

Thanks!!!
 

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MeWebdog said:
I ride a lot of mountains. I currently ride a triple drivetrain. I am building a new Parlee z2 and want to switch to a double ring setup.

Bottom line. . . Will the following setup work without to much chain slap?

Compact double 50/34 crankset; 12-30 - 10sp cassette; Medium cage dura ace 7800GS derailleur.

Next:
Same as above except use a dura ace 7900SS derailleur.

Thanks!!!
Your proposed set-up is virtually identical to what I run: 50/34 cranks, IRD 11/30 cassette and a short cage Ultegra 6700 derailleur. All components play together very nicely! Your 7800GS derailleur will also work very well with no issues.
 
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