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Old 03-11-13, 04:11 PM
  #27  
Ritterview
Tandem Vincitur
 
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Join Date: Sep 2005
Location: Northern California
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Bikes: BMC Pro Machine SLC01, Specialized Globe, Burley Rock 'N Roll tandem, Calfee Dragonfly tandem.

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Originally Posted by Dean V View Post
How do you come to the conclusion that you need to keep your cadence within such a narrow range to get optimum performance? I find that it can be quite variable, for me anyway. I have also done a bit of fixie riding on the road and even though your cadence is all over the place performance only seems to really suffer at the extremes (<40,>140 rpm).
If we look at pro riders, they will have a lot of watts/kg, and so don't need the low range gears that a tandem needs. So, they could dispense with gears, and have the jumps of turbotandem's. Do they use 6 speeds cassettes, or go with a single chainring sans FD? No, they use a double and 11-speeds.

Pro cassette from Cycling News:




Apparently, professional cyclists find that 'a narrow range is needed to get optimum performance'. So, the argument is settled by appeal to authority of pro cyclists. For the rear cassette, narrow jumps > wide jumps.


Turbotandem's Di2 setup (top), compared to a typical pro rider set up (bottom).




For a tandem, there are a lot of watts, but many more kg. Lower gears are needed. The question is which is preferable in obtaining the greater range needed on a tandem, (1) sticking to a double, expanding the range of cassette cogs, and accepting the jumps, or (2) obtain the needed range with a third chainring, and thus maintain the narrow jumps of a tight cassette.

It would be nice to have EPS or Di2, no doubt, and that might be reason enough. But if just mechanical shifting, I really don't see what I am giving up with a triple. It shifts just fine. The Lightning triple weighs only about 100 grams more than the double (and the smaller cassette is lighter). Because of the granny I can have both the wide range we need, and the narrow jumps of a professional cyclist.
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Last edited by Ritterview; 03-11-13 at 04:30 PM. Reason: removed superfluous word
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