Bicycle Mechanics - Use DA 7700 Cranks for Triple
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10-04-09, 05:00 PM
Are there any problems with using a pair of 7700 Dura Ace cranks (double) with the DA or TA triplerizer gears i.e., DA 7703 D chainrings (53D, 39D, 30D) or with similiar TA Shimano compartible rings in a triplerizer format? I would use the 118.5 BB.
Recall, the DA triplerizer hangs the granny from the 39D rings, not from 5 supports on the cranks.
Got spare 7700 cranks and would like to them use as a triple, most likley with smaller TA rings (48/36/28)
10-04-09, 07:40 PM
The only problem I can think of with respect to what you are attempting to do is that you won't be able to mount a 36T ring on a 130mm BCD crank. The smallest ring you can mount on that BCD is a 38T. Other than that, I see no reason why it wouldn't work.
How did you decide on the 118.5mm bottom bracket? The double and triple cranks obviously use different forgings so I would not assume that the double crank with the standard triple bottom bracket would yield the appropriate chainline. I would adjust the double's bottom bracket length by the amount of chainline difference between the triple and double crank (1.5mm on the drive side).
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