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SRM DuraAce 9000 (11-speed)
The SRM Power Meter 9000 is the latest SRM power meter supporting DuraAce 11 speed.
With up to 3000 hours of battery life, it’s a multi-year install-and-forget solution. That’s so long that the chainrings are likely to wear out before the battery.
Your author has used SRM power meter for over three years as this was written (with PC7 head unit), and they have proven highly reliable.
The Moot Vamoots RSL is still running a 10-speed Shimano DuraAce Di2 drive train and 10-speed chain (as of Spring 2014, see notes on Lightweight wheels also). This combination is working just fine with the DuraAce 9000 crankset.
WIND weighed the SRM 9000 50 X 34 crankset before it was installed on the bike.
Right crank and chainrings: 555g
Left crank: 181g
+6g for cadence magnet as shipped
A plain (non-SRM) 9000 crankset is spec'd at637 grams (not independently verified by WindInMyFace.com by weighing), so the SRM setup extracts an approximate weight penalty of a very reasonable ~104 grams.
- Add +102g on the Vamoots RSL with PressFit 30 BB for a Chris King PressFit 30 bottom bracket adapter = 843g installed.
- SRM Cannondale Hollowgram SL with Praxis chainrings weighs in at 678g, but the unit weighed is a single-battery unit (double battery units presumably heavier). Add +74g for the SRAM PressFit 30 BB adapter = 752g installed.
In short, the SRM 9000 DuraAce penalty is no more than 90 grams over the Hollowgram, and probably much less for the latest dual-battery Hollowgram setups. Of course one can run flimsy warpable chainrings on the Hollowgram to save more grams, but that is not a serious proposition for reliable use.
Data has to be displayed and recorded to be useful: the PC7 head unit and its mount add 65+ 15 = 80 grams.
Summarizing: for an SRM DuraAce power meter, there is a weight penalty of ~190 grams versus going without a power meter and without a head unit of any kind.
When one considers that a Garmin or similar with mount and cadence magnet and speed sensor chews up about half that difference, the SRM power approach looks pretty awesome for what it does.
Power measurement is transmitted to the Power Control 7 wirelessly from the strain gauges in the SRM Power Meter crankset. Other head units can be used also, such as the Garmin Edge 500 or 800 models.
See the discussion of how SRM measures power. As shown, the power shipped from SRM.
View larger, view HD.
Overall description as per SRM
The new SRM PowerMeter 11-Speed is the next generation of seamless drivetrain integration for Shimano groupo users and Power enthusiasts.
Improving over the 7900 series SRM PowerMeter, the 11-Speed now boasts 3000 hours of battery life! Electronic shifting systems make gear changes faster and virtually eliminate missed shifts, but the forces on the chain rings are much higher than with mechanical derailleurs.
With this in mind Shimano developed new Dura-Ace 9000 chain rings which are 20% stiffer than previous rings. This not only benefits the shift, but also in power transfer from the crank arm through the spider and into the drivetrain. If you ride Shimano DuraAce 9000 mechanical or Di2 electronic, you will benefit from increased power transmission!
Available models: SRM-Shimano 11-Speed: 110mm BCD (53/39), (50/34), (52/36)
Details as per SRM
Powered By Experience — Each SRM PowerMeter and PowerControl head-unit is made one at a time, by hand. Our production facilities are located in Jülich, Germany and Colorado Springs, USA. Every step of production is carried out by highly trained engineers and technicians who have a passion for quality craftsmanship .
Accuracy is Everything — SRM uses a 144 point calibration protocol against a known mass measured to the exact gram. With precise calibration and our Auto-Offset feature, the resulting power measurement of the SRM has error of less than 1%. The scientific community has been publishing peer reviewed research for over 20 years using the PowerMeter as the bench mark for measuring power in physiological and human performance research studies. We don't claim anything, our accuracy is proven.
Dependability you can count on — Each SRM system is designed to withstand the rigors of training and racing in all conditions! The internal battery of the SRM PowerMeter allows for worry-free training while maintaining the industry's leading waterproof PowerMeter design. A three-year global warranty against defects backs up your investment and offers peace of mind. SRM maintains its hard earned industry leading accuracy and data transmission to yield unrivaled power measurement performance!
Race Proven Durability — PowerMeters are designed to take whatever you can throw at them. Each SRM is sealed against water, snow, mud, sand, and cleaning solvents. SRM PowerMeters are designed to work. We back that up with a three-year global warranty. If you can break it, we'll fix it.
WIND would add that SRM service has been excellent. A product is the sum of hardware and software and service; it is not a box and a spec sheet.