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Tandem Cycling A bicycle built for two. Want to find out more about this wonderful world of tandems? Check out this forum to talk with other tandem enthusiasts. Captains and stokers welcome!

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Old 12-01-08, 08:07 PM   #1
merlin2
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2008 IRD question

I have been reading about all the problems associated with IRD cassettes in the various threads. I see by their web site, IRD now offers an extended range(11-34) cassette that is Campy compatible. We would like to mate this with Campy Chorus shifters(10sp). It would seem this would eliminate the need for a J-tec shiftmate/Shimano cassette combination. Does anyone have current info on matching these with either current XT or XTR RD's? The info I have read is from 2007 or earlier and talks about compatability issues with certain Shimano RD's.
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Old 12-01-08, 09:34 PM   #2
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Originally Posted by merlin2 View Post
I have been reading about all the problems associated with IRD cassettes in the various threads. I see by their web site, IRD now offers an extended range(11-34) cassette that is Campy compatible. We would like to mate this with Campy Chorus shifters(10sp). It would seem this would eliminate the need for a J-tec shiftmate/Shimano cassette combination.
OK, I'm sitting here slack-jawed at that offering. If you haven't done so, do me a favor and send IRD's tech support folks a note and ask them what shifters and rear derailleur they're recommending you use with their Campy 10 speed cassettes ON TANDEMS.

I won't bother to outline all of the various other [Campy / Campy / Shimano] OR [Campy / Shimano / Shimano] configurations you can already run without a JTek as you should have also run across those during your IRD cassette searches. If you didn't, well, they're covered ad nauseam in the archives as well.

Last edited by TandemGeek; 12-02-08 at 07:59 AM.
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Old 12-02-08, 12:42 AM   #3
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Wow.

That would be pretty cool to use with a Campy Comp Triple RD, if it would work.

EDIT***
Here's the chart:

IRD (Campy) 11-34 (10s)
11,13,15,17,19,21,23,25,28,34

For comparison
SRAM PG-970 11-32 (9s)
11,12,14,16,18,21,24,28,32

Sorry... I don't like the jump from 28 to 34... sheesh!

Last edited by uspspro; 12-02-08 at 12:48 AM.
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Old 12-02-08, 12:52 AM   #4
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Now the 11-30 10-spd looks interesting

11,13,15,17,19,21,23,25,28,30

Why 28 instead of 27 though?
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Old 12-02-08, 07:59 AM   #5
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That would be pretty cool to use with a Campy Comp Triple RD, if it would work.
That's the operative question and the reason for my initial reply: just what rear derailleur are they recommending this thing be used with ON TANDEMS?

While I've heard folks say that they were able to make 34t cassettes "work" on tandems with earlier Campy Racing-T rear derailleurs with their medium/longish cages I found the upper limit to be 28t and a stretch at 30t on tandems running 28t - 32t granny gears with 54t big rings on tandems with standard length rear stays.

Since '02 we've been using up to 32t cassettes with Campy long cage Chorus & Record rear derailleurs on our Erickson tandems and it's a stretch with 30t and 32t granny gears coupled with 54t big rings. What I've found is that while you can shift into the 32t, the amount of chain required to wrap the 32t/54t "big/big" ring combinations causes the teeth of the rear derailleur's guide or jockey pulley (that's the upper one) to "kiss" the teeth on the 32t sprocket even with the B-screw set to it's max. Again, the combination "works" but you can hear a distinct mechanical noise coming from the jockey pulley and cassette in this combination. And, IMHO, you MUST always set up a tandem so that the chain is long enough to support the "big-big" combination, lest you bind up your drivetrain and/or damage your rear derailleur.

Now, I will note our Calfee's chainstays are about 1" shorter than the Ericksons (similar to a single bike) and only uses a 53t "big ring". The shortened stays & reduced tooth count on the big ring make for a drive chain that's 2" shorter than on our Erickson which has eliminated most of the interference between the derailleur's jockey pulley and 32t sprocket with the 30t granny ring. However, I'd be surprised if there wasn't a lot of interference with a 34t sprocket. I've never even bothered to check as I don't even own a 34t cassette even for our off-road tandems: 32t has always been "good enough" for road or off-road.

Now, at least for single bikes, I wouldn't see any interference issues with a 34t on a bike running a compact drive with a 50t or 48t "big ring", and I suspect that may be the target market for this cassette.

Anyway, take it for what it's worth... As I said, I'll be interested to see what they recommend since the defacto solution for anyone who has wanted to run a 34t cassette has been to spec a Shimano XT or XTR rear derailleur that is designed with the needed capacity.

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SRAM PG-970 11-32 (9s)
11,12,14,16,18,21,24,28,32
Shimano uses the same cog sizing for it's 11x32t 9 speed cassettes.
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Old 12-02-08, 09:09 AM   #6
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Now the 11-30 10-spd looks interesting

11,13,15,17,19,21,23,25,28,30

Why 28 instead of 27 though?
I think there is a typo there. Other places they list it as a 27. I sent them an email awhile ago but did not receive a reply.
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Old 12-02-08, 09:24 AM   #7
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On tandems and single bikes, I prefer to use a smaller inner front chainring, either a 26 or 28 tooth in place of the stock 30 tooth, instead of using a wide-range cassette on the back. Then you can use a standard road cassette (I use ones going up to anywhere from 25 to 28 teeth depending on the bike), a standard road rear derailleur, and still have super-low climbing gears. This gives the advantage of having tighter spacing between the gears when shifting between cogs on the back, but you have to accept the downside of needing to make bigger changes in cadence when shifting between chainrings on the front. However, shifts on the front happen far less often than shifts on the back, so the advantages outweigh the disadvantages IMO.
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Old 12-02-08, 01:18 PM   #8
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Does this cassette fit on a Shimano splined hub or a Campy Splined hub? I guess I'm too lazy to go to IRD's site...

Nevermind, I went to the site. It fits on a Campy hub. What Campy compatible hubs are out there for 140-160 spacing ? Coupled with the derailleur issue, this is a curious offering.

Last edited by dfcas; 12-02-08 at 01:31 PM.
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Old 12-02-08, 03:39 PM   #9
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What Campy compatible hubs are out there for 140-160 spacing?
Off the top of my head and at least for 145mm hubs: White Industries, Rolf, Topolino and most likely DT/Swiss. White and DT/Swiss most likely offer Campy compatible 140mm hubs, but none of them offer 160mm hubs (period).

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Coupled with the derailleur issue, this is a curious offering
Remember, there is no such thing as a "tandem-specific" cassette and I haven't seen anything that suggests this particular cassette is targeted for the tandem community. While I'm sure you could make it work on a tandem (poorly with some creative chainring / chain length configurations), I'd be more inclined to see this as something for the compact drive users who need something with shorter gearing than Campy's 13x29t and who just didn't want to use a triple crankset.
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Old 12-02-08, 05:00 PM   #10
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I sure wish Campy would pull their heads out of their you know whats and produce an 11-29 or better yet an 11-32 rear 10 speed cluster. While you can make your own 11-29 using I believe it's Veloce cogs since they are all individual and you can match up the correct A and B cogs (I run a Campy 11-26 on both my wife and my roadbikes) it's just not enough for us. I like have a bailout gear to spin on long long climbs.
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