SRAM Patent Shows Different Electronic Shifting System for e-Bikes

Nov 19, 2020 at 10:49
by James Smurthwaite  

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.
Archer Components review
There are definitely similarities between the Archer D1x we tested in 2018 and SRAM's new patented design.

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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.

One of the patent diagrams features an e-MTB but this product could have been designed with commuter e-bikes more in mind.

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.

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Member since Nov 14, 2018
1,770 articles

  • 156 15
 We want gearbox
  • 20 2
 That is the plus side to ebikes as they can overcome the inefficiency inherent in gearbox applications for human powered bikes.
  • 22 59
flag dwee (Nov 19, 2020 at 12:32) (Below Threshold)
 @juansevo: The only positive of ebikes is that Paul Bas can ride again, and others in a similar boat. Other than that, they are a nuisance
  • 14 3
 3 speed wide range gearbox at the front, paired with a tiny 4 speed rear derailleur. You could even move the freehub into the gearbox which would improve the performance of rear suspension due to less unsprung weight.
  • 10 10
 We don't need gear box. We need this to happen in MTB.
  • 9 0
 And wearable solar panels
  • 3 0
 We do!
  • 4 0
 CVT integrated into the motor unit and a belt drive to the rear wheel
  • 2 0
 @Flinty: is that like the Hammerschmidt I still have (and not used in 5 years)
  • 1 0
 Nicolai eboxx rohloff. Gates belt drive, 14 speed electronic rohloff. Expensive, heavy and draggy, but oh so low maintenance.
  • 6 0
 @Flinty: Why would you add the weight and drag of a gearbox w/out getting rid of the maintenance of a cassette and derailleur. Seems counterproductive.
  • 2 2
 @dwee: You know that's not gonna happen when this is SRAM you're talking about. They're gonna give you a bigger rear platter with a new XD driver that's incompatible with previous version. C'mon - gearboxes are passé - get with the program with the e-bike drivetrain. It'll Make America Great Again! Big Grin
  • 1 2
 @CSharp: I can’t wait for the day when I’m passing ebikes uphill using their 60t cog
  • 1 2
 @dwee: LOL....that is most tides for me...passing most ebikers...
  • 3 0
 @nigelh: actually, there is a company (Revonte) that announced a CVT unit in their electric bike... I have used CVT transmissions before in other applications and this would be the tipping point if they can figure out how to minimize weight and drag. However, the electric unit should be able to neutralize any nuance of drag so mostly weight... So, we are pretty close to having the best case technologies in eMTB's...
  • 2 1
 "A justifiably sizable price tag"

Manufacturer cost for AXS its about 30 percent of the retail price.
  • 4 0
 @endurocat: That's how business works!
  • 1 0
 @Flinty: SRAM Dual Drive.
  • 1 0
 @shawndashf1: Classified claim that there's no extra drag in the 1:1 ratio while the 1:0.7 ratio is said to be '99% efficient'. So much for the claims, only real world reviews can confirm.
You can use much smaller and lighter cassette than 10-51 and have the same gear range.
Imagine having narrow 7 or 8 speed cassette - less cross chaining means less drag,
Hub can have wider spoke flanges - no need for boost/super boost? Can be used on any bike, if you switch the frame, you keep the wheel and run it on new bike.
You can use any crank you want, no need for proprietary nonsense.
  • 4 0
 @chillaxin: Thanks for bringing us up! The Revonte ONE Drive System will distinguish itself in the current market in several ways, and the combined gearbox and motor is just one of them.

For those interested, check the articles linked below.
  • 1 0
 @juansevo: yeah but when are they going to mate the gearbox to an e-bike and be done with it!?

Also, handlebar clutter?! Really, we're talking one cable here as the shifter is still present... and also bear in mind that with a mechanism like this they'll probably lose the weight benefit of their current system over the standard cable actuated set up. I guess as it's solely for the e-bike crowd though weight won't matter so much.
  • 1 0
 @Revonte: is your system broadly similar in approach to the Toyota hybrid system? Looks to be from the diagram. Mechanically, it ought to be high 90s% efficient. I assume that, like the Toyota, at some "ratios", you end up with one motor absorbing and the other driving, and with electronics and so on, you'll be maybe 90% efficient for that bit. So, at a guess, your system efficiency might scrape past 90%? Given that you still need the chain or belt, surely the gearbox plus straight chain will be less efficient than the losses from a bent chain and a couple of jockey wheels. But maybe that's not sooo important when you're motorised.
  • 1 0
 @nigelh: continental made one
  • 1 0
 @Revonte: Welcome, I am a big fan of what you folks are doing in this space... In fact, I will touch base directly to continue dialogue.
  • 31 0
 It seems a little complicated just to save ~5 feet of cable and housing. And who the hell thought that placing electronics right where the chain slaps was a sensible idea?
  • 23 0
 Maybe the target market doesn’t even know that chain slap is a thing!
  • 7 0
 @aka-bigsteve: I just don't understand how this could be better. It's taking a system with two main parts (two main assemblies if we're being pedantic) that are connected with a cable (or wireless with axs) and replacing it with a three part system to save a few feet of cable. How does that make sense?
  • 5 0
 @kcy4130: It allows the e-bike computer to control the shifting with a less expensive system than currently exists.
  • 5 0
 @Skooks: Oh, it allows the ebike to reduce power while shifting. Thereby reducing the likelihood of breaking/wearing drivetrain parts if you shift under load. That is a solid plus.
  • 2 0
 @kcy4130: also all the other benefits of electronic shifting like a clean cockpit and better shift quality.
  • 3 0
 @kcy4130: yeah and you can get away with a bend hanger way better because the electronic systems could find the right spot for each gear. You can't do that with a simple mechanical shifter if each cable pull is the same. That is in my book the best thing about it.
  • 1 0
 @kcy4130: it makes cool robot sounds
  • 31 6
 You want a gearbox and a motor to overcome the inneficiency.... Have you considered that what you want is actually a MX bike?
  • 9 3
 I did consider it and decided that I don't want a bike that weighs 200 pounds and is more fun to go uphill than downhill. Plus wearing those heavy stupid boots and the risk of getting injured. I love watching moto racing but it's an easy sport to hate on.
  • 1 2
 @DoubleCrownAddict: you seem fun at parties...
  • 1 0
 @jts429: I'm guessing you recently bought a $10,000 motocross bike and realized you still need the stupid boots?
  • 20 4
 In all the years and years of cycling it is unbelievable we still use the derailleur and cassette for our gears. Of all the innovation this has remained stagnant apart from refinement. Isn't it about time we had a wicked compact lightweight gearbox with electronic shifting and retired the rear mech and shifter to the history books. Its long long over due.
  • 4 0
 People were saying this 10 years ago with regular bikes, the resistance to gearboxes is even more ridiculous now that e bikes are a thing. The reason Sram is pushing this garbage is because they aren't in the e bike game so this is the only way they can gain profit off it. I imagine the only reason e bike manufacturers aren't using gearboxes is because it would hurt their efforts to make e bikes look like regular bikes, using as small of motor as possible. So basically the people making fun of the big appearance of e bikes is what's holding us back from gearboxes, i.e. Pinkbike commentors.
  • 9 1
 How much are you willing to pay for this wicked compact lightweight dream catching dual overhead foxtail gearbox?
Fact is chain-on-sprocket is far better for power transfer than any spur gear assembly. Gear shifting mechanisms are extremely complex, requiring either engagement dogs shifting forks and barrels or planetary gears, sprag bearings, clutch plates and shoes.
  • 2 6
flag MattP76 (Nov 19, 2020 at 23:35) (Below Threshold)
 @JoshieK: Motorbikes and cars have been managing it for decades.
  • 8 0
 @MattP76: Have you seen the size of a car or motorbike gearbox recently? And have you done any research on the frictional loss of said gearboxes?
  • 2 5
 @JoshieK: Hang on let's get a grip here!! We live in 2020 do we not? Currently NASA are using a private taxi firm to shuttle Astronauts to the ISS. Yet you are suggesting there isn't the expertise and talent out to make a great gearbox for a mountain bike? Seriously???
  • 15 1
 @MattP76: ZOMG!!!! its the current year!!! I never knew!!! Drive train losses for spur gear driven boxes is still in excess of 10%, a chain by itself as used on bicycles is better than 97% efficient. Until Space X came along, the only way to put man into space was the R7 Platform Soyez rocket which was also the first rocket to put man into space. All of the airplane (as in not rocket propelled) speed and altitude records are set by a plane which first flew in 1963 - apart from some avionics this plane hand no upgrades. The F1 rocket dyne that powered the Saturn V was first tested in 1957. The point i am making is there hasn't been a whole lot of mechanical advancements in recent times. Since the late 1980s/early 1990s our advancement has been all electronic/software. There is expertise to do a lot, but changing the laws of physics isn't one of them.
  • 1 9
flag MattP76 (Nov 20, 2020 at 3:11) (Below Threshold)
 @JoshieK: Yawn!
  • 1 1
 @JoshieK: That 7% loss in efficiency isn't gong to make much difference on an e bike, especially if you are riding it in turbo mode. While it probably wouldn't appeal to the weight weenie/xc e bike consumer, I do think that the alot of the Enduro/ freeride/ Downhill e bikers would gladly trade away the efficiency of the outdated road bike derailleur system for the reliability of a gearbox. But the #1 factor preventing gearboxes isn't efficiency, it's appearances and cynical idiots complaining that the motors look too big so they won't ride them.

Both the manufacturers and the consumers of this sport are short-sighted, stubborn, and close minded to a certain degree, but especially the manufacturers. That's why there is only 1 manufacturer that makes a real DH e bike(Husquavarna), and it isn't anything special.
  • 2 1
 @mattP76 completey agree. The issue is probably that sram and shimano and LBS are making money from riders replacing worn out drive-train parts so there is no incentive for any of them to develop maintenance free and more efficient options.
  • 2 1
 @DoubleCrownAddict: 7% is insignificant - news to me. The rest is just hyperbolic and your opinion not "facts" or "factors".
  • 2 0
 @JoshieK: When you factor in the power of the e bike motor that 7% loss in drivetrain efficiency would mean hardly anything, no more than a 1 or 2% difference between an e bike with a gearbox and a e bike with the shitty, unreliable, outdated road bike derailleur system. Might not even be 1%, very insignificant.

If people still want derailleurs on their regular snail bikes that's understandable, they are so slow they need the efficiency. But it is time for derailleurs to be thrown into the trash bin of technology for the majority of e bikes.
  • 1 1
 @DoubleCrownAddict: wow 7% is equal to or less than 1%. Thats some brilliant maths there bruh.
  • 1 0
 scam would stifle anything that compromised their company with lawyers.
  • 12 0
 Are they patenting the 1995 AMP ebike too?
  • 5 0
 I think they are trying to show an early 2000s Stumpjumper FSR ebike conversion.
  • 11 4
 I wonder if all this AXS stuff is EMP safe?
Could a person with ill intent just blast a bike with a little EMP and completely ruin someone's day?

Note I would do such a thing because I'm not an a*shole, but plenty of those people do exist.
  • 24 0
 I am not sure if I would want to get out for a ride just after WW3 started.
  • 27 0
 @paulcgn: "I was JRA in the nuclear wasteland when my bike stopped shifting. Is that covered under warranty?"
  • 9 0
 I worry more about the lizard people than I do EMP's.
  • 5 0
 Only case we’d see an EMP blast is nuclear at the moment. It’s been a sort of holy grail of military weaponary goal for a long time, it has yet to become a reality on it’s own. Not really an issue.
  • 5 0
 It really depends on what levels of EMP you are talking about. Everything will fail at a certain amount, (including humans). All product sold in the world (Especially North America and Europe) is subject to electrical immunity and safety testing, which basically ensure that the products do not fail when exposed to large blasts of electromagnetic radiation, and that the system does not have any mechanisms of failure that would hurt the user.

Check out: IEC 61000-4-6 and IEC 60950-1
  • 5 0
 @steflund: That's very helpful. Thank you.
  • 5 0
 Its safe in the sense that in order to disrupt the communication from any real distance, you need a pretty powerful "jammer" which is a federal offense in US. If you have the skill to build one without being put on the list, Im betting you got better stuff to do than go after people riding bicycles.
  • 4 0
 All it takes is one solar flare to ruin your ride. Nuisance sun.
  • 5 0
 @ilovedust: 2020 isn't done yet!
  • 1 0
 @steflund: Just on the paper the other day i built a circuit with just a coil and a transistor, known as joule thieve, and I beefed up the power out, and with no load it gave off EMI strong enough to jam the FM reception of an hifi module and then shut it down and to change randomly the channel on a tv box a bit further away. And it was't its intent, it was to power LED series from a pc monitor. With load there's no EMI
  • 1 0
 @FCX250: Why do you need a joule thief to power an LED from a PC monitor? Normally they are used in battery applications.

Anyway, I would believe it and of course the switching frequency of your coil will dictate what gets jammed. FM is a continuous wave low-frequency transmission, so if you were switching in the 100 MHz range then that makes sense.

To jam AXS devices you need to have 2.4GHz transmitters which emit a continuous wave very close to the receiver, which in and of itself can be violating the specifications under which they were certified.
  • 1 0
 @steflund: Cheap self regulating VRM, I think it worked as a low power RF bomb emitting at several frequencies with a bit stronger centre, but I didn't investigate further as I don't have the equipment to measure and possibly optimize it for that purpose. (I think even my smarphone reacted to it by turning on the screen, not sure though, it was some time ago)

No, you don't need 2.4GHz to jam axs, you just need a frequency that interferes with any critical part of the circuit, as any length of conductive area in the PCB is potentially an antenna you just need to induce an high enough voltage, through the resonant frequency to disrupt correct functionality, the only hope is them having put enough RF decoupling capacitors and eventually coils, at least for GSM, LTE, etc, I believe they have.
  • 8 1
 While this is touted as a shifting system, I think the true potential lies in the possibility of integrating this system into a suspension lockout or other compression adjustment. Wireless remote lockout without two extra cables coming off of my handlebars? Yes please.
  • 2 0
 Is a suspension lockout, or a 'propedal' feature (reduced travel or increased damping) necessary, or even beneficial on an ebike?

Serious question because I've only tried ebikes a few times. I found that pedalling efficiency on the ebike was not an issue, so I'd prefer the suspension to be tuned to absorb the terrain and didn't care about support when cranking at all.
  • 1 0
 @ozhuck2flat: I'm not talking about on an ebike. I'm talking about regular bikes.
  • 5 0
 Looks similar to a previous design, therefore there is prior art and the patent pr patent application could be worthless.
Is it novel? Doesnt look novel. So what is the value in the parent?

It amused me some of the things we could patent and some of the things we couldnt.
Could this be a blocking patent rather than an application one?
  • 2 0
 Great points. Also, I'm not sure if Pinkbike understands the difference between an awarded patent and a patent application.
  • 1 0
 Im not very versed on Patents (including reach outside of the country it is filed in) but I was given advise as basically follows - If you are not willing and able ($$$$) to defend your patent in court then its a futile exercise.

When we see the likes of say Weagle apply for a patent because he moved a pivot point 3mm you realise for the most part they are nothing more than a dick measuring instrument.
  • 2 0
 @JoshieK: patents are very valuable in business.

Some companies encourage their R&D employees to come up with blocking patents, these are designed to block a competitor from further development of a product, both in direct technology and adjacancies.

Trying to come up with methods for patent avoidance can be part of the art of engineering.

There are countries who like making counterfeit goods or buying legitimate registeted goods from a country where they are cheaper and repackaging them. Both can be illegal if a product has to be registered for example. Companies may have teams who go after these counterfeit operations or patent infringement companies.

Different countries have different rules around patents and products and different registrations for patents/products etc. Knowing this landscape is a minefield and left to regulatory experts, both locally and globally.
  • 1 0
 @betsie: Sounds like the sort of bureaucracy that would follow such a thing. And you are saying that potentially because of the similarity to a previous product that a patent might not stand up in court?

I see Porsche came out with a variable pin height connecting rod for engines recently. The design is fraught with problems (such as hydraulic poggo, weight and piston slap due to the eccentric pin) and perhaps that is their intention - to block.
  • 6 1
 At this point why aren't they just building frames with solenoids, actuators and servos built in and powered by the ebike battery??
  • 5 0
 Perfect. eBike battery runs out of juice on highest (hardest) gear. No way you ride back.
  • 2 0
 That's probably pretty unlikely, if they design it right.
The power usage of tiny derailleur motors and its control system is tiny compared to the ebike motor and its drive circuitry. If they plan out a system shutdown sequence when the battery gets low, they could turn off the motor and still have enough charge for everything else on the bike (displays, handlebar controls, head and tail lights, derailleur, suspension controls etc) to work in low power modes for days. Of course, if they don't you have an expensive adult kick bike.

For example- you can still use your car stereo when your car battery is too flat to kick over the starter motor.
  • 5 0
 I wouldn't be surprised if this filing was only to keep Archer from optionally tapping into ebike batteries for power.
  • 1 0
 bullying lawyer tactics from scam. worse than specialized for stifling true innovation
  • 2 0
 I always thought the Archer stuff was well suited for working with manufacturing to make a chainstay that would either allow the unit to sit inside, or tuck in behind, secured in placed with bolt. Or hidden up inside the main triangle, removing at least half the house and cable from the shifting setup. Or better yet, bolted directly to the SRAM already has done. Why is SRAM working on this junk when it should just be looking to put AXS on everyones bikes (and at affordable prices)?
  • 2 1
 Solar Flares man, that's what you need to be worried about. Geomagnetic storms are going to knock us on our behinds one of these days. And I'll be riding circles around you E-bikers. Payback's a beeeeyotch! Long live pre-stretched shifter cables!
  • 1 0
 Sram released a really fantastic looking e-bike drive train a couple of years back called EX1 I was going to use called while building up my ebike recently so took a closer look

Seemed perfect , just 8 speeds with narrow width cassette made of steel and 11-46 gears, what more do you need / want ?

Prices looking good,

Shifter £48
Rear mech £140
Chain £25

The all steel cassette, must be cheap, just checking, oh must be an error, £425.

Double check, yep it really is £425, they decided to machine it out of single piece of steel.......

On top of that the chain is effectively a 10 speed which means it probably will not work with the 11/12 speed compatible X-Sync chainrings for the new motors. ( They did make compatible front rings for the earlier ebike motors though using the tiny cogs)

They should revisit this and make a cheaper pinned steel cassette like GX or even the cheaper NX and a 10 speed compatible front ring.

I sure they would get plenty of sales , would happily use it on a non-bike.
  • 2 1
 Are you seriously ??
back in 2017 I launched the news on
  • 6 1
  • 4 0
 I'm still waiting for voice-controls: "HEY SRAM, SHIFT UP!!!"
  • 2 1
 That's probably not too far off. Imagine the tricks you could play on your friends!
  • 2 0
 The axs electronics are so cheap already. They sell for a lot because there isn't a true competitor atm. They really don't need to do this sort of setup at all.
  • 2 0
 This patent is to stifle the small competitor Archer. To prop up scam´s margins for marketing koolaid.
  • 2 0
 The real question here is: Why does the hand piece shown look EXACTLY like a BOSCH Intuvia Control Unit??
  • 1 0
 I was thinking the same!
  • 2 3
 Fits with SRAM’s published strategy of making replacement parts crazy expensive - ‘oh, you damaged your ebike derailleur? No, you can’t use a normal one, you’ll need the eSRAMDM that’s 3 times the price of the others’
  • 1 1
 so much problems with Cable actuating derailleurs?

I do think most people that think about this BS, should ride more, and feel the real need of any MTB that spends some hours on the saddle.... in the moutains!
  • 4 2
 Archer components ripoff.
  • 1 0
 Not sure how this gets downvoted. They poached an employee then suddenly have this patent going through. Snide rip off and blocking tactics - if it was specialized acting like this it would be front page news.
  • 3 2
 Sram just out to rip off the ingenuity of smaller companies that are actually making the real changes in the
  • 2 1
 This patent is of course a cheap automatic shifting system for the commuter e bike market. Nothing else.
  • 3 1
 We don’t need your junk sram
  • 1 0
 Sounds like the Terminator
  • 1 3
 Field Test, Field Test, Field Test, Field Test, Field Test, Field Test, Field Test, Field Test, Field Test... You get the idea, I guess.
  • 1 1
 Cheaper than AXS, yes, but simpler? Not really.
  • 1 1
 Man, that's an old patent. From ~2003, by the looks of that specialized.
  • 2 3
 What a waste of time! Give us a gearbox.
  • 1 1

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