A patent filed by SRAM in September and first spotted by Bicycle Retailer and Industry News
could reveal a version of electronic shifting that has the potential to be cheaper than its current AXS offerings.
SRAM's current electronic drivetrain is totally cable-free and uses a small electric motor, two clutches and a gearbox to actuate the derailleur, plus an encrytped wireless network to relay inbetween the shifter and the derailleur. In short, it's a very complex, high-tech piece of equipment that sits right at the top of SRAM's range and it carries a justifiably sizable price tag along with it.
This new design is totally different from that, and looks similar to a device we tested in the past from Archer Components
. This system uses a standard mechanical derailleur, but instead of the cable being routed inside or along the frame to a shifter on the handlebars, it is cut short and fed into the cable puller that sits on the chainstay on the drive side of the bike. This cable puller is then operated wirelessly from a handlebar switch. It's easiest to think of it as a chainstay-mounted shifter that you operate from your handlebars.
There are definitely similarities between the Archer D1x we tested in 2018 and SRAM's new patented design.
The Archer D1x gives a pretty good idea of how the SRAM patented design might work
The main difference between the SRAM and Archer pullers comes in how they are powered. Whereas the Archer 1Dx uses a small removable battery, much like SRAM's own AXS, this new design will rely on the power of an e-bike's battery. The patent says: "Previous designs of electronic cable pullers were self-powered, often relying on batteries... The present disclosure provides examples of electronic cable pullers that may be powered by a centralized battery of an electric power assisted bicycle ("e-bike") and may not be internally powered."
Translating that patent-ese, we believe this design will be something that is integrated into the electronics of an e-bike. This is something we've seen previously with headlights, ABS and even 4G computers
but this would be the first time derailleur shifting would be involved with that as well.
On top of this, SRAM even hints that the product wouldn't necessarily need rider input and could shift automatically to provide the best cadence for a rider depending on the terrain they are riding, or if they change the power mode of the motor. While the patent does include a diagram of a potential shifter design, the patent also says, "Additionally or alternatively, the shift control may send the gear change signal to the electronic cable puller without user input. For example, in response to a sensed change in terrain or heading, the shift control may automatically send a signal to the electronic cable puller to change gears. In some cases, the shift control may be part of or in communication with a controller of an e-bike. The shift control may send a gear change signal to the e-bike controller which may send a signal to the electronic cable puller via the wire to change gears.
So, why would SRAM make this product when it already produces a wireless drivetrain? Simply, this strips away a lot of the intricacies of the AXS system so will likely be a cheaper and simpler way to get rid of handlebar clutter. There's still a lot we don't know about this system though. Is it designed with mountain bikers in mind? How much is it expected to cost? Will it ever even see the light of day? And does SRAM have more plans for e-bike integrated technology? SRAM is tight-lipped about its patents so we'll have to keep guessing until it's ready for the market.
View the patent, here