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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 09-11-06, 09:51 AM   #1
garysol1 
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Sunrace Cassette and Deore Question

I am trying to fix a shifting problem on my Burley. The bike is factory equipped with a Taigra STi's, Deore rear derailer and a Sunrace 9-speed 11-32 cassette. The chain is a SRAM pc951 chain. I have adjusted the cables to get a perfect upshift(from small to big) but when I try to go down through the cassette the chain will stay on the cog it was on until I have shifted down twice. The chain will then go down 2 gears so I have to upshift one to get my desired gear ratio. If I only click down one gear nothing really happens except a bit of noise until I shift a second time. Anyone else had this issue? I am thinking maybe it is just a miss match combo but really the only thing non factory is the SRAM chain.
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Old 09-11-06, 10:08 AM   #2
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Sounds like dirty, crimped or burred cable housing won't let the slack out of the cable correctly.
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Old 09-11-06, 01:17 PM   #3
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What he said . . . or something else

Yes, it might be something binding between the cable and housing (a burr, kink, friction). You might try dripping a little chain lube into the housing.

Or, it might be too much adjustment. You might have made the downshifting (shifting to larger cogs / easier gears) TOO good. I've worked on indexed shifting systems before and got them where they seemed to shift flawlessly from smaller to larger cogs, but then they wouldn't shift back without hesitating.. Screwing the adjusting barrel back in a turn or 2 usually balanced things out.

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Old 09-11-06, 02:28 PM   #4
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Asides of possible cable/housing issue mentioned, some lube on the STI inner workings could help.
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Old 09-11-06, 02:54 PM   #5
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A couple of thoughts...

Terminology: Even though the chain is being move "up" the cassette, upshifting is technically the opposite... you upshift into gears that are "harder to push" and you downshift into gears that are "easier to push". I understood what you were trying to say, but it's worth while to keep the terminology straight or -- if you're like me -- limit your comments to describing what the chain is doing which you also did.

OK..... Question Time

1. Was it working well to begin with on the road when you took possession from KnoxBreezer?

2. If not, what was the chain doing as it ran up and down the cassette before you started to adjust it, in what direction, and between which number sprocket(s) (e.g., moving up from 2nd to the 3rd smallest sprocket).

3. What all did you adjust or change?

4. Have you been doing all of your adjusting in the workstand without any resistance on the rear wheel or have you road tested it with your stoker to see how it is shifting under load?

5. Before doing anything else, have you made sure that the B-screw is adjusted correctly? If you aren't sure, take a few minutes to review the infomation on Park Tool's rear derailleur adjustment "how-to" guide:
http://www.parktool.com/repair/readhowto.asp?id=64

Anxiously awaiting your feedback (well, not really... but feel free).
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Old 09-11-06, 03:26 PM   #6
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Also, especially with a tandem, because of the extra long cables and frame, it might be adjusted just fine empty, but when loaded, the frame sags a bit, pulling the cables a little tighter. Therefore, you may have to tweak it "on the fly." Tandems are persnickity that way.
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Old 09-11-06, 05:02 PM   #7
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Quote:
Originally Posted by Old Hammer Boy
when loaded, the frame sags a bit, pulling the cables a little tighter. Therefore, you may have to tweak it "on the fly." Tandems are persnickity that way.
Good point Hammer. I removed the cable today and there was a bit of a kink where the outer cable fits into the sleeve that goes into the cable adjuster. I lubed her up real good and I also lubed up the STi shifter the best I could. Shifting was much improved with just me on the bike. I will have to wait to load her down to see if I really fixed the problem. Thanks for the tips guys.
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Old 09-11-06, 05:13 PM   #8
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Quote:
Originally Posted by TandemGeek
OK..... Question Time

1. Was it working well to begin with on the road when you took possession from KnoxBreezer?
No, I dont think so. But it did take a few miles for me to get used to the bike and really notice it. Something may have gotten knocked around between Knoxville and here.

Quote:
Originally Posted by TandemGeek
2. If not, what was the chain doing as it ran up and down the cassette before you started to adjust it, in what direction, and between which number sprocket(s) (e.g., moving up from 2nd to the 3rd smallest sprocket).
The problem is pretty much limited to going from larger to smaller. 7 to 6 shift is almost impossible. I will click twice and shift from 7 to 5...then back UP to 6

Quote:
Originally Posted by TandemGeek
3. What all did you adjust or change?
Primarily just the barrel. Today just before I posted this I did lube and clean the cables and shifter and it seems to have cleared up alot of the problem. I may need to replace the rearmost outer cable.

Quote:
Originally Posted by TandemGeek
4. Have you been doing all of your adjusting in the workstand without any resistance on the rear wheel or have you road tested it with your stoker to see how it is shifting under load?
Without the Stoker. Shame on me. I never even thought about the flex till Hammer boy mentioned it

Quote:
Originally Posted by TandemGeek
5. Before doing anything else, have you made sure that the B-screw is adjusted correctly? If you aren't sure, take a few minutes to review the infomation on Park Tool's rear derailleur adjustment "how-to" guide:
http://www.parktool.com/repair/readhowto.asp?id=64
The B-screw I assume is a high or low stop. The stops seem fine but I shall read the guide.



Quote:
Originally Posted by TandemGeek
Anxiously awaiting your feedback (well, not really... but feel free).
I feel the love But seriously guys....I so much appreciate the real help. As soon as I learn more I promice to repay the board by being as helpful to other tandem newbies as you guys have been to me.
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Old 09-11-06, 07:42 PM   #9
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Reinforcement....

1. The closer the upper jockey wheel is to your cogs as it travels up and down the cassette, the more precise the shifting will be. The "B Screw" should be nearly all the way in, as illustrated on Park's web site given that you have a 32t, even closer to being all the way in for a 34t. Something to keep in mind if you have reason to change the size of your rear cassette...




2. For tandems, more so than single bikes, you will need to make a final "tweak" to the rear derailleur using the in-line cable adjuster (found on bikes that use indexed shifting) while riding the tandem with a stoker. This has more to do with how the drive chain will perform while under the very high tension that is developed by a tandem team and less to do with potential frame flex-induced shifting issues which are fairly rare nowadays. Learn how to use your in-line adjusters while you're working on the bike in the stand so that you can make "on the fly" tweaks to dial out chain chatter... it doesn't usually take more than 1/2 a turn, but you need to be sure you're able to know which way to turn the adjuster's barrell to get the desired effect otherwise you may find that you make things worse, not better.

3. Anytime you cannot dial-out shifting problems with your rear derailleur, suspect a bent derailleur hanger and have a bike shop check it with an alignment tool.

Last edited by TandemGeek; 09-11-06 at 09:29 PM.
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Old 09-16-06, 10:10 PM   #10
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Quote:
Originally Posted by TandemGeek

3. Anytime you cannot dial-out shifting problems with your rear derailleur, suspect a bent derailleur hanger and have a bike shop check it with an alignment tool.
A dead giveaway that the hanger is out of alignment is when you get good shifts from the rear derailleur with the chain on one ring, but you no longer get good shifts in back when you shift the chain to another ring.

If you have a steel frame or the frame has a steel derailleur hanger, a hanger alignment tool is nice to have. I often pack one with me when I travel with the bike in a soft case, as the frame sometimes gets bashed in wierd ways in transit and you never know what's going to be bent at the other end of the trip. The derailleur hanger is pretty vulnerable to bending in transit.

- L.
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Old 09-17-06, 07:50 AM   #11
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Quote:
Originally Posted by TandemGeek
3. Anytime you cannot dial-out shifting problems with your rear derailleur, suspect a bent derailleur hanger and have a bike shop check it with an alignment tool.
Absolutely agree! If for no other reason than to rule it out as a source for your shifting problem. My experience has been that more than half of the time, that's it.
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