Choice of SRM's Power Control head units does require an additional wireless sensor to pick up the speed. Choosing a Garmin as a head unit eliminates this due to their GPS capabilities.(Image credit: Richard Tyler)
SRAM's Quarq crankset saves some 36 grams over its SRM counterpart.(Image credit: Richard Tyler)
A magnet mounted near the bottom bracket registers cadence.(Image credit: Richard Tyler)
The Quarq doesn't have a dedicated head unit. ANT+ compatibility makes Garmin's Edge 705 a front runner to fulfill the role.(Image credit: Richard Tyler)
A user-replaceable battery is a big plus for the Quarq unit. SRAM suggest most users will get around nine months of use before having to replace the battery.(Image credit: Richard Tyler)
Eponymous with power meters, SRM have joined forces with SRAM for 2010.(Image credit: Richard Tyler)
The challenge of accomodating the power measurement hardware led SRAM to develop new unidirectional carbon fibre crank arms.(Image credit: Richard Tyler)
The SRM's data is transmitted wirelessly via an inconspicuous sensor mounded beneath the bottom bracket. Both the SRM and Quarq versions of SRAM's crankset are compatible with the BB30 design.(Image credit: Richard Tyler)
SRAM's SRM is compatible with the Power Control 7 head unit. The soon-to-be-released PC8 will also mate with the cranks.(Image credit: Richard Tyler)
SRAM has thrown itself headlong into the world of power measurement with fully-integrated crankset collaborations with both South Dakota-based company Quarq and German power pioneers, SRM. After reporting strong uptake of the systems through the Australian summer, SRAM is hopeful of similar success as the US and European thaw out from their record-breaking winters.
SRAM's power cranksets are based around Quarq's relatively new CinQo Saturn and the SRM's long-standing and well proven unit. Compatible with all of SRAM's road groupsets the cranksets do however differ from the design formula for the company's standard crank options.
The spider-mounting of both the Quarq and SRM systems meant SRAM couldn't simply transfer the carbon arms from their Red and Rival groupsets. Instead, the carbon arms featured on the power units were specifically designed to accommodate the necessary hardware. Each version includes its own unique spider and both use a 130mm BCD for standard-sized chainrings. Available crank lengths range from 170mm to 177.5mm.
In terms of frame compatibility, the cranksets can either be coupled with SRAM's GXP bottom bracket or the growing list of BB30 options.
Adorned in SRAM livery, the SRM version is of course compatible with the Germany company's own PowerControl VI head unit and will also work with the forthcoming PowerControl VII. Quarq doesn't offer its own computer head at all but since both systems employ the ANT+ digital wireless protocol, power-ready third-party units such as the Edge 705 and 500 from Garmin, iBike's iAero, and CycleOps' new Joule 2.0 will readily pair up.
Direct-measurement power meters still remain premium products cost-wise but with the cranksets sold independent of the head unit options, there are some significant levels of leeway in the the outlay required for each system. For example, with an MSRP of US$2300 for the SRM crankset option, the cost difference between the SRM PowerControl VI (US$1,000) and Garmin Edge 500 (US$250) allows some flexibility for prospective purchasers.
Specifications
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Product: SRAM S975 Quarq Power Meter crankset Crank arms: Unidirectional carbon over internal aluminium skeleton (170mm, 172.5mm, 175mm or 177.5mm) Spider: 130mm BCD Chainrings: SRAM Red PG Chainrings (53/39T) Weight: 884g (with SRAM GXP bottom bracket) MSRP: US$1,800
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