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Discussion Starter · #1 ·
Is it possible to assemble a 13-27 Shimano 9-speed Ultegra cassette out of a 12-27 and a 13-23?

The only one Shimano lists with a 27 cog is a 12-27 and a 12t cog would be just wasting a gear.
 

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You would be better off using a 13-25 and a 12-27.
The 13-25 ends with a 21-23-25 unit and the 12-27 ends with a 21-24-27 unit.

You would end up with two good cassettes. A 13-27 and a 12-25
 

· A wheelist
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Discussion Starter · #3 ·
MR_GRUMPY said:
You would be better off using a 13-25 and a 12-27.
The 13-25 ends with a 21-23-25 unit and the 12-27 ends with a 21-24-27 unit.
You would end up with two good cassettes. A 13-27 and a 12-25
Point taken. The reason I mentioned the 13-23 is that it's the only one of the three to have an 18. It would give me the ability to try the 18 in the mix. Of course, something else in the middle cogs would have to go to accomodate this and that's not great either.

Even if I had gone 10-spd from the start, the only 10-spd with a 27 (which I really want) is the 12-27 and it doesn't have the 18 and the 12 is useless to me. The 10-spd with an 18 is the 13-26.

Arrgghh! I guess I should just go ride eh?
 

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13-23's have a 13-14-15-16-(17-18)-(19-21-23)
If you use the (21-24-27) from a 12-27, you would have an 18 to 21 jump in gears (not good)

If you need the 18, you would need to start with a 14-25 cassette and end up with a 14-27
 

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Discussion Starter · #5 ·
MR_GRUMPY said:
13-23's have a 13-14-15-16-(17-18)-(19-21-23)
If you use the (21-24-27) from a 12-27, you would have an 18 to 21 jump in gears (not good)
Yep I've been playing with the numbers all day and that 18-21 jump isn't good.

If you need the 18, you would need to start with a 14-25 cassette and end up with a 14-27
I have a 14-25 on The Bike right now and really, the 25 isn't low enough and the 14 not high enough. I struggled up my biggest hill yesterday and I can't pedal fast enough to get much above 28mph with that 14.

I was checking Andy Hampsten's Dirt Road Bike and he has 12-27 ten-speed. I need a 12 like a hole in the head so with a 13-27 I'd have the same gears as Andy if you look at his lowest nine cogs. Of course he's a bit stronger and a lot younger than me :rolleyes: and that's why he has 50/34 on his bike and I have 46/34.

After much deliberation I think I'll be ok with a custom 13-27. I can sell the left-over cassette on e-bay after I've robbed it.

Thanks for your help Grumpy!
 

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Now this is ...

MR_GRUMPY said:
You would be better off using a 13-25 and a 12-27.
The 13-25 ends with a 21-23-25 unit and the 12-27 ends with a 21-24-27 unit.

You would end up with two good cassettes. A 13-27 and a 12-25
...creative!

TT
 

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A number of years ago, I was pissed about the cassettes available for mountain bikes because I hated the 3 to 4 tooth jumps on the larger cogs. So I purchased a dura ace 12-25 cassette along with a boone(maybe?) single 27 tooth cog. I removed the 14 from the cassette and stuck the spacer behind the 25 and stuck the 27 on. I ended up with a 12-13-15-17-19-21-23-25-27. I was planning on finding an 11 to replace the12 but never got around to it. The shift from the 25 to the 27 isn't quite as smooth as the 23 to th 25, but it's still shifts nicely IMHO. You could do a similar setup and the nice thing about it is that you can remove the 27 if-when your fitness level allows it. Looks like you'd need a 12-25 to start with, unless a 13-25 is made.
 
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