ALPhillips

I have a Shimano 12-27 ultrega 10 speed cassette now. I'd like to convert it to a 14-34 by adding some flat clogs (30t and 34t) and a first position 14t (if it exists) to make a 14-15-17-19-21-23-25-27-30-34. I dont not like the 11-34 10 speed offered by IRD because i do not need the 11t, 12t, and 13t for my situation. Is this an option for my 10 speed? Any other suggestions?

Anyone heard of a 14t first position 9 speed cog being ground down to the width of a first position 12T 10 speed cog?

Thanks, Anthony

Ex Pres 

Shimano makes 14t first position cogs for their junior [racing] geared cassettes.

My guess is that cog is a little pricey from them, however.

HillRider

Shimano makes an Ultegra-level (SC-6600) junior-geared 14x25 10-speed cassette but they make no 10-speed cogs larger than 27T. You may be able to add a 9-speed 32 or 34T cog behind that cassette and remove one of the intermediate cogs to make room. I don't think you will be able to fit two or three 9-speed cogs into the stack as their greater thickness may not allow the lockring to thread on.

BTW, Shimano also makes a 16x27 10-speed SC-6600 cassette if you are really willing to give up any small cogs to get the 27.

I think it would be less expensive just to buy the 14x25 or 16x27 and add a 32T cog than trying to juggle the 12x27 with a bunch of loose cogs.

ALPhillips

thanks for the info. Anthony

Al1943

There have been postings saying that you can't add a single cog to the back side of a Shimano 10-speed cassette because of the conical design. I don't have any 10-speed Shimano cassettes so I'm not sure what that means. I have added single cogs to the back of 9-speed Shimano cassettes.
I'm wondering if it would be possible to start with the IRD 11-34 and change a few cogs.
I have ground down the built-in spacer on a first position 13 cog to make it the same thickness as a 9-speed. This is an easy job on a bench grinder, the steel is too hard for filing.

Al

mechBgon

I've seen several IRD 10-speed 11-34 cassettes, and they don't seem to be spaced right. Get the indexing dialed for the high end, and it's off on the low end. Get it dialed on the low end, and it's off on the high end. Different chains, different derailleurs, low-normal, top-normal, nothing really fixes the core issue: the spacing from cog to cog is wrong. So unless they fess up to a spacing problem and revise their design, I wouldn't bother with IRD's cassette if I were you.

Bill Kapaun

I don't have any 10 speed stuff, but it was my understanding that the 3 largest cogs are on a carrie and can't be separated???
I made an 8 speed cassette by using EIGHT, 7 speed cogs and thinning the 7 speed spacers to give me 8 speed spacing. (center to center)
Maybe you could buy a 9 speed cassette with the needed 3 larger cogs, and thin the spacers?
Maybe that's what IRD does, without being fussy enough about spacer thickness.
According to my info, a 10 speed cog is .0071" thinner and the spacer is .0083" thinner than 9 speed.

mechBgon

IRD's using alloy spiders for the larger cogs. But it's the same fundamental problem: the spacing's not correct.

As for the OP's overall goal, it might be possible to simply switch to a compact triple (22-32-44) to effectively turn the 12-27 into the equivalent of a 14-34, provided the necessary 10-speed chain jives OK with the crank's ring spacing. But I don't know what the OP's current crank setup is, so who knows. In that scenario, the Shimano SLX or DeoreXT cranks would be worth a look.

Deanster04

You would also need the get the XT FD and RD for that setup. The FD would be needed with the XT Triple front crank set and the RD would be needed to take up the wide range 22 x 27 using the long cage. An older 105 long cage DR would work as well. Good LUck.

Al1943

I don't know what kind of frame we're talking about but if the front derailleur is a braze-on type it's probably not going to adjust low enough for a chainring set smaller than 50-39-28 approximately.

Al

mechBgon

There would also be the question of front-derailleur indexing compatibility, which will depend on what type of shifters this person uses (road STI, bar-end, road flatbar, mountain flatbar). Unfortunately, we're working from scanty information here.