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2011/2012 Look 695 SR — Crankset Options
Related: bicycle power meter, Road Bikes, Shimano, SRM
I have direct feedback from a LOOK 695 SR 'Collection Unique' user that Shimano DuraAce DI2 electronic shifting is less than ideal with the LOOK chainrings (which are not as stiff and beefy as DuraAce).
Installing an alternative crankset
For Shimano DuraAce DI2 users, as well as those wishing to run an SRM power meter crankset, LOOK offers a bottom bracket adapter which allows installation of an alternative crankset (other than the LOOK ZED-2 carbon fiber crankset).
Weights
Palo Alto Bicycles (highly recommended) accommodated me for a second test ride with my SRM 7950 crankset installed, I had my usual Lightweight Obermayer wheelset on the bike, of course.
I weighed the LOOK 695 SR test bike with the SRM 7950 crankset installed, one bottle cage and no SRM mount at 14.6 pounds. Note that it was a demo bike without the E-Post.
Subtract about 1/20 pound for the seat weight difference and add 1/20 pound for the second bottle cage and subtract maybe 2/10 pound for the E-Post, and perhaps the bike could be built up with the SRM 7950 at 14.4-14.5 p0unds. My Trek Madone 6.9 SSL with two bottle cages, double-thick bar wrap, and the SRM mount is 14. 3 pounds (same wheels/tires/pedals).
That is what I wanted to know. No meaningful difference in terms of weight.
Crankset details
To replace the LOOK ZED-2 carbon fiber crankset with a Shimano or other crankset, one needs to install a bottom bracket adapter, as well as a bottom bracket.
Weights as weighed, parts weight could obviously have some minor variation (172.5mm crank arms):
LOOK crankset; rings, BB, pedal inserts (complete): 661.5 grams
LOOK bottom bracket adapter: 78.7 grams
Shimano DuraAce bottom bracket: 89.2 grams
Shimano DuraAce 7950 crankset: 661.4 grams
SRM Shimano 7950 50 X 34 crankset: 778.1 grams
In other words, the DuraAce setup costs you +168 grams, and the SRM 7950 power meter option costs you +285 grams (+117g over plain no-power DuraAce).
I deem a weight penalty of 168 grams to be well worth the improved shifting, and personally I won’t ride without a power meter, because it is so darn useful.
In summary, the 3 choices come down to:
LOOK ZED-2: 661.5 grams Shimano 7950: 829.3 grams = +167.8g (661.4+78.7+89.2)
SRM 7950: 946.0g = +284.5g (778.1+78.7+89.2 + mount, head unit)
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