Tandem Cycling - most appropriate derailleur for my tandem?

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gregm
08-12-07, 12:58 PM
Looks like my front derailleur may be getting a bit beat up. Can folks toss out some ideas for the most appropriate replacement? Here's the setup:

o Shimano 105 brake/shift levers (105s are double/triple ready - same part for doub or trip)
o Thorn 160mm stoker cranks with 28/38/48 steel ramped & pinned chainrings
o 31.8 stoker seat tube outer diameter
o frame has bottom pull cable routing
o stock derailleur is bottom swing, with clamp between H2Obottle cage screws; top swing might find clamp interfering with bottle cage mounting hole
o 9 speed rear

I won't tell you the older, stock model that's currently on there, as it may not be quite the most suitable, and I don't want to influence your responses. ;)

So, would a SRAM mountain derailleur be a good value and do a superb job, or would it not play nicely with the shifter? Would an Ultegra road triple be best friends with the shifter, and do well enough with a 48 big chainring? Whaddya think??

Thanks!
-Greg

SDS
08-12-07, 03:17 PM
I used to use 24/36/48 rings with an Ultegra triple front derailleur operated by the Ultegra STI lever to climb Mount Evans in Colorado on my single bike. I just slid the FD down the seat tube until it was close to the chainrings and it worked fine. If I did it again I would use 53/39/28 and probably an 11-33T cassette.

In North Texas I find the best tandem rings to be 53/39/28. It's true that the nominal FD capacity is 22 teeth, but 25 works well enough.
gregm
08-12-07, 05:20 PM
Cool! Thanks. An example that works. :)

Performance has 'em on sale, I may just go with this. I also have another tandem crankset with bigger rings, so the flexibility would be nice.

Cheers,
-Greg

gregm
08-12-07, 10:53 PM
A follow-up...

Would a current Ultegra triple front derailleur, presumably intended for a 10speed chain, travel far enough across my three (possibly MTB-spaced?) Thorn chainrings with my 9speed chain, when driven by the 105 shifter?

-Greg
sch
08-15-07, 04:49 AM
Ultegra triple for 10spd likely to have a slightly narrower cage, hence
a bit more chain rub will occur. Should have more than enough
reach, assuming the CWs don't sit too far out from the BB shell. You
can eyeball this from above and compare with another DF.