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mixing & matching cassette cogs(19 posts)

mixing & matching cassette cogsweiwentg
Nov 28, 2001 8:38 PM
I've got a 11-21 Dura Ace cassette. problem is, it won't get me up the monster hills. can I use the 23 and 25t cogs from my old Tiagara cassette to replace the top 2 cogs?
re: most likelydzrider
Nov 29, 2001 6:09 AM
I've done this stuff over the years with little or no difficulty. The jumps between your last 3 cogs would be awkward. I suspect you'd go 19-23-25. 19-21-25 would be more useful if it's possible to replace only the largest one.
re: most likelyweiwentg
Nov 29, 2001 7:56 AM
i don't think it's possible - the last 2 cogs on the DA cassette are connected. I dunno about the old cassette. anyway, awkward for me isn't a problem, just so long as the bike can handle it.
Not just,TJeanloz
Nov 29, 2001 8:29 AM
The simple answer is no.

The long answer is: on the 11-21 Dura-Ace cassette, the 19 and 21 are pinned together, and the 16 and 17 are pinned together. And they aren't pinned the old way- they cannot be disassembled. If you have a Tiagra cassette, depending on what your old ratio was, you'll probably have the 17-19-21-23-25 pinned together. I believe these are also stuck to their carrier, though I'm not as familiar with Tiagra.

So you could probably have the bottom 4 gears be DA, followed by 5 Tiagra gears- but at that point, why not use the whole Tiagra cassette?
re: mixing & matching cassette cogsLC
Nov 29, 2001 10:04 AM
Get rid of the 11 that you do not use anyway and just add the 25. Drill out the rivets heads and pry the 25 off. I have done something like this and it works great.
You have never done anything like this...TJeanloz
Nov 29, 2001 10:10 AM
If you were to drill the rivets off a Dura-Ace cassette, the cog that you were left with would have no splines on it. It would be pretty tough, no, impossible, to install that on a freehub body.
You have never done anything like this...LC
Nov 29, 2001 6:30 PM
The 25 is on the Tiagra cassette, and that can be separated without problem.
re: mixing & matching cassette cogsKStone
Nov 29, 2001 12:45 PM
One way to get the cassette choice you want is do this. You will need an old used 8spd xx-23 cassette for the 23 cog and will be adding it to the 9spd setup while removing one of the loose 9spd cogs.

Remove the 23 cog from an old 8 spd xx-23 cassette. Remove the 9spd cassette from the wheel, put on the single 23 cog and one of the loose 9spd spacers.
Replace the 9spd 3 cog spider and check the shift ramp alignment with the 23 cog. The correct alignment will be visually obvious and can be corrected by removing the 23 cog and filing the wide spline narrow to match the rest. The 23 cog can now be indexed on the freewheel hub for shift ramp alignment (8 different ways). Reassemble the rest of the 9spd cassette leaving out the l biggest single 9spd cog.
I've done this many times and regularly switch back and forth for hilly terrain. I've never experienced any shifting or chain problems but suggest you try this setup yourself.
re: mixing & matching cassette cogsKStone
Nov 29, 2001 1:02 PM
Hold on there... I just read your prior question..." guys, how do I install a new cassette? do I just put the chainrings down on the hub and tighten the screw? do I have to align them in some specific manner? or do I HAVE to get the LBS to do it?"

My previous advise of swapping cogs is NOT for the mechanicaly challenged.

re: mixing & matching cassette cogsmclements
Nov 29, 2001 5:30 PM
You've gotten some complex answers to a simple question.

I've done exactly what you are talking about and have a simple answer for you. I customized my Shimano cassette to the following: 11-12-13-15-17-19-21-23-25. I've been using this for about a year now and it totally rocks! This is the setup Shimano should ship out-of-the-box. It gives a wide range of gears, with smooth transitions between the ratios. And contrary to what one person said, the 53/11 gear ratio is very useful for those > 40 mph descents.

It's very easy if you are starting with a 12-25, but since you're starting with a 11-21 you'll have to buy more parts. That's because only the smaller sprockets are individual; the larger ones are grouped together.

I wrote up the simple procedure here:

Just go to a good bike shop with the above numbers, and you will be able to order the parts to put together the cassette you want.

P.S. the Ultegra sprockets will last longer than the Dura Ace ones.

Good luck,
He got complicated answers,TJeanloz
Nov 30, 2001 7:22 AM
He got complicated answers because they were the correct answers to his question, which was: Can I use the 23 and 25 tooth cogs from my Tiagra with my new Dura-Ace cassette.

The question that you answered, quite easily, was: Can I make an 11-25 cassette?

The answer to your question is a simple yes, the answer to his question is a complicated no.
He got complicated answers,weiwentg
Nov 30, 2001 7:34 AM
so, I can't make a hill-climbing cassette out of my old one and my new one, BUT if I get the properly-sized Dura Ace cogs, I CAN make a new cassette. right?
frankly, I think computers are FAR more easy to fix than bikes. I've been biking for 3 months and am terribly confused. I sat down and assembled my computer over a course of 3 days. it was tough, but doable.
Nov 30, 2001 7:47 AM
You could get the big Dura-Ace cogs- but because they're titanium, they're really expensive individually. You'd be better off getting the set of three large Ultegra cogs.
re: Am i stupid or what....Rusty Coggs
Nov 29, 2001 6:17 PM
Why not just buy a 12x25 or 12x27 either Da or ultegra and be done with it?
re: Am i stupid or what....mclements
Nov 30, 2001 8:11 AM
I agree that the 12-25 is the best "OTB" set of ratios that Shimano provides. But it is nice to have an 11 for those fast downhills.

So then you'd have to modify it to get the 11, which really means an 11-12-13 instead of 12-13-14, to smooth out the ratio transitions.

However, of all the different Shimano cassettes, the 12-25 is the best to start with because it can be converted to the 11-12-13-15-17-19-21-23-25 with minimal changes.
re: Am i stupid or what....weiwentg
Nov 30, 2001 6:43 PM
I think I'll get a set of 23-25 cogs. then I'll ditch the 12 and the 14 during races. that will leave me with a 11-13-15-16-17-19-21-23-25. 25 for the insane uphills, 11 for when I get over the top. does that sound sensible, or does that sound like an insane scheme by a demented young biker? :P
seriously, does that sound all right?
re: Am i stupid or what....mclements
Nov 30, 2001 6:53 PM
The gears you suggest will probably work, but the ratio transitions might not be as smooth as you'd like. The 16-17 will be a 1-tooth delta surrounded by 2-tooth deltas.

If you can put this together in your garage without having to buy any parts, why not give it a try? But if you have to order parts anyway, you might as well order up a set of gears with smoother ratio transitions (e.g. 11-12-13-15-17-19-21-23-25).
re: Am i stupid or what....weiwentg
Nov 30, 2001 8:13 PM
i'd like that. but 16 and 17 are, sadly, stuck together. and no, I will not cut off one tooth from the 16 :P
re: mixing & matching cassette cogsmclements
Dec 2, 2001 11:11 AM
One thing that I forgot to mention (and nobody else mentioned either):

There are two different sizes of the round end caps for the Shimano cassettes. The one used on the casettes that have a 12T smallest gear, is different from the one on those that have an 11 T smallest gear. The 11T end cap has a slightly smaller diameter, and the threaded "neck" is about a millimeter or so longer.

So if you ever change your smallest cog, you might need to get a different end cap. The 11 T end cap _might_ work with a 12T end gear, but the 12 T end cap definitely will _not_ work with an 11 T end gear.