A new patent from SRAM suggests the American components manufacturer is plotting its entry into turbo trainers with a unique double-chain design that could make indoor cycling more straightforward.
Published on Thursday, the patent is for an indoor trainer with a “closed loop component”.
The design appears to work by attaching the bike directly into a mount, and disengaging the chain from the cassette. The chain is then placed onto a separate cog, itself attached to another cog, which drives another chain linked to the resistance wheel.
The bike is attached to the trainer with “axle supports”, meaning the only element that needs to be moved is the chain. Neither the back wheel nor the cassette are engaged, and are therefore not set in motion.
SRAM’s entry into the smart trainer market seems like a natural progression, given the brand’s expertise in power meters, groupsets, and wireless communication - all foundational elements of a high-quality trainer.
The design shown here appears to use a single sprocket, eliminating traditional gearing. This approach mirrors the Wahoo Kickr Core Zwift One trainer, which simulates gear changes through digital resistance adjustments. Zwift achieves this with its Zwift Play system, a handlebar-mounted controller that lets riders shift virtually.
However, SRAM’s advantage lies in its wireless shifting technology. If SRAM integrates bike-mounted shifters directly with the trainer, it could offer a seamless indoor riding experience. This innovation would represent a significant leap forward in smart trainer design.
SRAM’s design – potentially the company's first turbo trainer – seeks to resolve the limitations of existing trainers, which are split into wheel-off and wheel-on categories.
In the first instance, where users have to remove the rear wheel, a separate cassette is often needed, as well as adjustments to the derailleur.
Wheel-on trainers do not require the rear wheel to be removed, but can cause wear on the tyre, which is typically engaged for resistance. So as to not deteriorate their road tyre, wheel-on trainer users tend to fit a separate training tyre to their bike.
“In both cases [wheel-off and wheel-on], installing a bicycle on a trainer may require significant mechanical aptitude, time, and additional bicycle components,” the SRAM patent says. “In addition, various components may experience additional wear with either type of trainer, whether in the drivetrain and/or on the rear tire.”
SRAM’s proposal allows users to leave the rear wheel on the bicycle while bypassing the cassette and rear wheel. This, the patent says, means wear on the tyre and cassette “may be greatly reduced”.
“In addition, the bicycle may be quickly and easily installed on the trainer without the need to remove or adjust various components.”
As with all patents, there is no guarantee that this product will ever be made into reality. The patent filing means SRAM has protected the design, and may do with that what it wishes.
Last month, SRAM also published a patent for a ‘smart wheel accessory’ – a bike wheel with an integrated sensor capable of feeding back live data on tyre pressure, rim health, and wheel lean.
Cycling Weekly has approached SRAM for comment on the indoor trainer design. In the past, a SRAM spokesperson has said the company does not comment on patents.
