Quote:
Originally Posted by benb
For me personally I would really like to continue to use cranks that actually matched whatever group I picked that just have the PM added. Either OEM or something like what Stages or 4iii do, not stuff that is a completely new/different crank design that doesn't match anything else.
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There are power meter cranks that will completely match the rest of the groupset from all 3 major makers (Shimano, SRAM, Campagnolo), but there are serious disadvantages to all 3 options. Shimano's power meter crank has major accuracy issues, so it is more of a power guesser than a power meter; the SRAM power meter crank appears to be accurate and reliable, but it is disposable - the power meter is built in the chainring, so when the chainring is worn out you'll need to replace the power meter; and Campagnolo's new power meter is not only very expensive, but first reports are that it has poor accuracy.
The next closest option is to use OEM cranks with replaceable spiders, and use an aftermarket spider. Several SRAM cranksets have replaceable spiders, and there are multiple makers of SRAM compatible power meter spiders (both 3 bolt and 8 bolt). The same crank arms used in Campagnolo's power meter cranks are also used by SRM and Power2Max, so these will also closely match Campagnolo drivetrains. For Shimano, the only options I'm aware of are Stages and 4iiii, which will mount their power meter modules to OEM crank arms. A single sided crank arm system will be cheaper, but it may provide less accurate results if a rider's legs have different power outputs; a double sided crank arm will be more accurate (and can show how much power is contributed by each leg) but will be more expensive than a spider based power meter.