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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 06-08-11, 05:56 PM   #1
rdtompki
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The Great 12-28 Experiment

I'm replacing our 11-32 Shimano cassette with a 12-28 SRAM for all but the less than 10% or our rides that have sustained climbs at or above 9 or 10%. The spacing on this cassette (12-13-14-15-16-17-19-21-24-28) will really help our cadence mismatch and make the majority of our riding more enjoyable. I also have one of the Harris 13-30 cassettes, but I had some difficulty getting it to shift well.

This will take a bit of getting used to since I'll be shifting more cogs in the back as I change chain rings, but I don't see that as much of an issue.

Anyone else running this cassette on their tandem? It does look like it will work well on our unusual quad chainring setup, but I don't know about a normal road triple.
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Old 06-08-11, 06:19 PM   #2
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That cassette should work well. We use a Shimano 12-27 same cogs with the exception of a 27 rather than 28. I like it with a triple 24/36/50 chain ring set. We only rarely use the 24 and find the 36-27 is generally low enough on most climbs. Top speed pedaling is about 34. We usually coast above 30 anyway.

If I recall you have Davinci with quad chain rings. Is that correct?
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Old 06-08-11, 06:23 PM   #3
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What is on the front (e.g. 52/42/30)?
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Old 06-08-11, 07:43 PM   #4
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Confession: we have a daVinci with (effectively) a 24-36-48-60 chainring setup. No way could be go to anything higher than 24-28 as our low gear. If we know the terrain I'll be able to pick the right cassette and on most organized rides in these parts I'll stick with 11-32. Solvang, for example, which is considered an easy Century, had a nasty 10% stretch at 80 miles.

I actually think I'll be less fatigued on longer rides since I'll be able to spend more time at a higher cadence.
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Old 06-09-11, 03:35 AM   #5
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Our setup has been for a long time 24/32/44/54 with a SRAM PG970 11/26 9 speed DH Cassette, (11,12,13,15,17,19,21,23,26).

In hand already, waiting for the next replacement when worn out we'll be the same front selection of 24/32/44/54 but will swap away from the DH cassette to a standard PG970 12/26 (12,13,14,15,17,19,21,23,26) which will close the gap on a portion of gear choice we normally ride.

Our 4 speed front is a something I was able to accomplish on account of us running flat bars and XO twist shifters with a road front triple der. We seldom use the 24 or 32, but they are still there for when needed. Initially we ran the 54 a lot more but have upped the revs and have better alignment running the middle 44 most of the time.

Seems we have enough gear spread and close enough steps to keep it easy to find a good balance of speed/rpm/effort. It works for us to have fun.

PK
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Old 06-09-11, 06:02 AM   #6
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We made a switch to a SRAM 11-28 soon after purchasing our Trek T1000. We couldn't stand the large gaps between gears on the stock 11-34. The 11-28 works great, nice linear shifting without huge gaps. We can use it for short climbs of up to 15% and for over 10% sustained climbs.
When I bought it I thought we'd swithch back to the 11-34 when needed but even though we live in a hilly area we haven't used the 11-34 at all since buying the 11-28. We'll save the 11-34 for when we go to Vermont where there are many 15-20% climbs.

Our front gears are 52/42/30
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Old 06-09-11, 02:08 PM   #7
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rdtompki - We use a 52-39-30 triple with a 12-27 cassette and find it to be ideal, for us. The close gearing allows me to tweak for cadence. We tend shift quite a bit because of this but it is really not an issue with the brifters and we are almost always in a very comfortable cadence. I tend to stay in the middle ring nearly all of the time and run through the cassette from 2nd to lowest to 2nd to highest gear, only shifting to a different chain ring when we want to go above or below that range. I choose not to use the extreme cogs in the cassette from the middle ring to minimize cross-chaining.

As we get older I may look for a way to get a lower gear but I think I will keep the 12-27 cassette and seek lower gears via a different chain ring selection.
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Old 06-09-11, 09:32 PM   #8
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12-28 Currently in a "fail" state

I could not get the 12-28 SRAM cassette to shift correctly after spending a couple of hours working the H limit and the cable tension. The strange thing is that I put the Shimano 11-32 back on and it shifted perfectly with no adjustment whatsoever. I'm not sure what other options I have regarding and SRAM cassette. I can go to a 12-27 Shimano (I think I have one sitting around), but that's a further compromise of our low end. IRD has a 12-28 so that might be something to think about; maybe I should sell some of my excess gear to further fund the experiment.

I'm open to suggestions!
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Old 06-09-11, 11:35 PM   #9
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I wasn't aware that SRAM now also offer a 12-28, that is good to know. I'm a big fan of that combination, and have used 3 different versions in the past couple of years. IRD and BBB both make 12-28 cassettes which have closer spacing in the lower gears in exchange for not having a 16 tooth cog:
12-13-14-15-17-19-21-23-25-28
They both shifted OK for me, but never as reliably as the Shimano 105 or Ultegra cassettes that I've used. The BBB cassette is pretty heavy because it is all individual steel cogs, the IRD is a bit lighter because it uses aluminum carriers for the larger cogs. When I started to miss not having a 16 tooth cog I then made a custom combination of parts of 3 cassettes to get:
12-13-14-15-16-18-20-22-25-28
This is the ideal gear combination IMO and I was lucky that it actually shifts pretty well.

We had been using the IRD 12-28 on the tandem with 26/39/53 chainrings, but I've had multiple problems getting smooth shifting on the tandem with this cassette and others. I've now gone for a 12-32 cassette and increased the inner chainring size to a 28. This has improved both front and rear shifting. The cassette is a Shimano XT 11-32, with the 11 and 12 tooth cogs swapped out for 12 and 13 tooth cogs from an Ultegra cassette to make it:
12-13-14-16-18-20-22-25-28-32
I'm really happy with this setup and plan to keep it for a while now.

Based on TandemGeek's recent blog postings on the matter, I've also just switched from a Dura Ace shifter with XT rear derailleur to a Campy Record 10-speed shifter and SRAM X-9 10-speed rear derailleur (without any cable pull adaptor). It seems to be working better than ever, but so far I've only used it on the stand and on a short test ride. I'm looking forward to giving it a proper workout, but it's looking really promising so far.

Last edited by Chris_W; 06-10-11 at 11:45 AM.
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Old 06-10-11, 08:29 AM   #10
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Chris, I like your switch to the 12-13 on the 11-32 cassette. This may be enough of an improvement to satisfy my search for perfect cassette. I have a new 12-27 laying around to I should be able to try this tomorrow.

I also have the Campy/SRAM setup and it does work perfectly (on the road) with the Shimano cassette. It's bafflng that the SRAM cassette wasn't even close to working.
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Old 06-10-11, 09:51 AM   #11
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We have used an Ultegra 12 - 27 for flat rides which we liked and switched to an XT 11 - 34 for hilly rides. We really felt the jumps after the Ultegra cassette and found it easier to stick with the XT 11 -34 all the time. Since then we have gone to chainrings of 26/39/50 with a 12 - 32 cassette. It gives us less top end but over all we like it better. Santana has a nice 10 speed cassette with 2 tooth (teeth?) jumps which I like on a tandem but it is $$$. Our shifters are Shimano STI. Barcons can shift a wider range than STI.
Sheldon and Martha Hall
Greenfield, IN
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Old 06-10-11, 06:18 PM   #12
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The custom 12-13-14-15-17-19-21-23-25-28 cassette looks great. I get all gaps at less than 13.4%.

I actually would like the Campy 13-28 cassette except I need it in Shimano spacing. It has 13-14-15-16-17-19-21-23-26-29 for one gap of 13% and others all less than 12%.
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Old 06-10-11, 08:29 PM   #13
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I borrowed the 12t and 13t from a Shimano 12-27 road cassette and replaced the 11t and 12t on my 11-32. Shift fine on the stand. The 13t with built-in spacer is definitely about .3mm thicker than the 12t mountain cog it's replacing, but the shifting still seems ok. We'll see how it goes tomorrow. I know I'm going to like th 12-13-14 better thant the 11-12-14. The 12-14 is a pretty big step. As for SRAM, I'm giving up, but this has been a good discussion.
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Old 06-11-11, 12:54 PM   #14
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In my experience, SRAM 10-speed cassettes shift as well as Shimano (and may last longer), but I prefer to use Shimano chains on both. Our PeriScope triple has a SRAM 11-28 ten-speed cassette. Works like a charm with STI. The 11t might be overkill on a two-fer with 700c wheels, but comes in handy on our looong bike with 26" wheels. The only drawback is the missing 16t, but I/we don't notice it that often.

YMMV, as always. Enjoy the ride.
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Old 06-11-11, 02:25 PM   #15
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I don't have a Shimano chain to experiment with (and I need two chains), but I might consider buying a couple of the least expensive chains keeping in mind that the SRAM cassette seemed pretty far"off". It's possible that the Shimano chains are a bit narrow - I've got one off a single that I can measure versus the KMC that I'm using on our tandem.

I did ride the modified 11-32 today and it was acceptable, but the shifting in the smallest cogs (12-13-14) was not as crisp as the original 11-12-14. I attribute this to the increased spacing between the second and third cogs. I'm going to try and find a Shimano 12t and 13t that have the same spacing as the orignal 11t and 12t.
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Old 06-11-11, 05:31 PM   #16
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We are running an Ultegra 11/28 on our new tandem along with FSA 53/42/30 chainrings and are very happy with the gearing and shifting, everything shifts great so far. DA front and rear derailleurs with new Ultegra brifters.
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Old 06-11-11, 10:17 PM   #17
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Regarding chain longevity, I recently read an independent test of chain wear using about 15 different chains, I think it was in the German Tour magazine. All the new series of Shimano chains (5700, 6700, 7900) came out on top as having stretched/worn less after a few thousands kms of simulated riding, with the other chains tested being old series Shimano, SRAM, KMC, and Campy; SRAM were some of the worse IIRC. Also, there wasn't much of a different between the new series of Shimano chains, with 5700 being about the same as the other two, so I plan to only use those from now on.

As for switching the 11 and 12 tooth cogs in a 11-32 cassette for 12 and 13 tooth cogs, I've not had any troubles on two bikes that I've done it with. The only place in the cassette where the shifting is sometimes not perfect for me is actually between the 22 and 25 tooth cogs on one of the cassettes, I'm not sure why.

Last edited by Chris_W; 06-11-11 at 10:21 PM.
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Old 06-16-11, 12:38 PM   #18
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I switched my 28/42/54 with 11-32 9 spd using a DaVinci modified SRAM X9 rear derailleur and Campy Record Ergo 10's to a a full Campy Record Long Cage with a 11-29 cassette and 26/39/53 rings up front. BEST thing I ever did. Highs and lows are comparable and way less overlap and more gears. Bike shifts flawlessly throughout the entire range. Using FSA front rings and a Shimano Dura Ace triple front derailleur.
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