[ad_1]
On June fifteenth 2023, a patent filed by SRAM was revealed to the USPTO database detailing a wi-fi chainring-integrated entrance shift mechanism for a 2x drivetrain. Therein, the standard entrance derailleur is changed by a shift equipment that’s mounted to the chainring itself, shifting because the chainring is rotated via every pedal stroke. That’s in nice distinction to generally out there entrance derailleurs which, with the notable exception of the Labeled Powershift Hub, are virtually solely mounted to the entrance triangle.
Let’s dig into the proposed workings of this entrance derailleur that’s housed totally on the crankset.
![sram chainring coupled front derailleur shift apparatus](https://bikerumor.com/wp-content/uploads/2023/07/SRAM-Chainring-Derailleur-Concept-patent-patrol_downshift-paddles-Fig-59-800x640.jpg)
SRAM Chainring-Coupled Entrance Derailleur
Earlier than detailing how the chainring-coupled derailleur (for need of a greater identify) works, the SRAM patent in query (US 20200140035 A1) discusses numerous drawbacks related to the present crop of entrance derailleurs. First up, as they’re virtually solely mounted to the seat tube, their mere presence forces constraints on body designers, stopping them from getting too inventive with body form for bikes which might be destined for a 2x drivetrain.
![sram force axs wide review](https://bikerumor.com/wp-content/uploads/2020/05/sram-force-wide-front-derailleur-test-ride-01-800x263.jpg)
Then, there’s the shifting efficiency to think about. A standard entrance derailleur consists of two steel plates that push the chain inboard or outboard, guiding it to a bigger or smaller chainring of the crankset, respectively. The SRAM patent says that this mechanism may cause tough transitions, which may turn out to be problematic below very excessive hundreds.
Additionally, tying the shifting mechanism to the seat tube successfully makes the entrance triangle a key part of the shift equipment. If it flexes below excessive torque, or when the bike hits a bump within the street (assume Paris-Roubaix), the place of the entrance derailleur will transfer away from its excellent place relative to the chainrings, placing the system susceptible to misalignment with imprecise shifting consequently. I don’t actually understand how usually that situation really causes subject, however the authors of the SRAM patent noticed motive to level this out.
SRAM suggest overcoming the aforementioned drawbacks with a brand new derailleur mechanism that {couples} the shifting system to the crankset itself. It reads, “The disclosed entrance shifting techniques shift easily and constantly, even whereas below heavy chain hundreds… [they are] simpler to put in and arrange than a conventional entrance gear changer or derailleur and don’t require particular expertise or coaching”.
![sram chainring integrated front derailleur upshift downshift](https://bikerumor.com/wp-content/uploads/2023/07/SRAM-Chainring-Derailleur-Concept-patent-patrol_shift-arms-Fig-4-800x480.jpg)
How does it work?
SRAM’s Chainring-Coupled Entrance Derailleur idea packs the entire equipment essential to information the chain from the large chainring onto the small chainring, and vice-versa, into the the large chainring itself.
In numerous the drawings, the inner workings of the distinct up-shift and down-shift parts are out of sight. They’re tucked beneath what the patent describes as an aerodynamic cowl that will additionally function a structural part that brings further stiffness to the system.
![sram chainring coupled front derailleur shift](https://bikerumor.com/wp-content/uploads/2023/07/SRAM-Chainring-Derailleur-Concept-patent-patrol_feature-800x533.jpg)
In fact, that is no mechanically-actuated shift mechanism. It is a wi-fi system, whereby up-shift and down-shift instructions are despatched from a bar-mounted distant – through Bluetooth or the like – to a receiver unit housed beneath that aero cowl. Accompanying the receiver is a detachable and rechargeable battery (purple) – that’s related in look to plain AXS batteries – a management unit, and a PCB. Seen externally, there’s a button for pairing the derailleur with the shifter (blue), and an LED that might be used to point battery life (yellow).
Additionally beneath that aero cowl is a motor and a collection of drivers, hyperlinks, shafts and pivots which might be rotatably linked to 1 one other in such a approach as to drive clockwise or counter-clockwise rotation of the up-shift and down-shift equipment (Fig. 11). We gained’t concern ourselves with the intricacies of that, solely with the intricacies of how the chain is transferred from one chainring to the opposite.
![sram chainring coupled front derailleur internal motor shafts pivots drivers rotate up-shift down-shift apparatus shift chain between chainrings](https://bikerumor.com/wp-content/uploads/2023/07/SRAM-Chainring-Derailleur-Concept-patent-patrol_complete-mechanism-Fig-11-800x640.jpg)
![sram chainring integrated derailleur holes on big chainring body missing teeth on big small chainrings](https://bikerumor.com/wp-content/uploads/2023/07/SRAM-Chainring-Derailleur-Concept-patent-patrol_bare-chainrings-Fig-37-800x640.jpg)
Earlier than we get began, take note of the structure of the chainrings proven in Fig. 37 (above). Right here, the chainrings are proven with out the chain or any of the shifting equipment hooked up. The buildings labelled 264a-d are literally holes that permit for protrusion and retraction of the up-shift equipment (seen in inexperienced in later photos). And, very importantly, each the large chainring and small chainring look like lacking one tooth, one other attribute that’s important to the workings of the up-shift mechanism, as will turn out to be clear.
Onward, and upward…
The Upshift Mechanism
Right here, we’ll delve into the up-shift mechanism; how the chain is transferred from the small chainring to the large chainring. To kick off this clarification of the up-shift mechanism, we’re going to counter-intuitively begin by trying on the components of the downshift equipment – 212a and 212b, proven in purple.
![sram chainring integrated front derailleur upshift downshift](https://bikerumor.com/wp-content/uploads/2023/07/SRAM-Chainring-Derailleur-Concept-patent-patrol_shift-arms-Fig-4-800x480.jpg)
When the chain is working on the small chainring, these two hooked arms are positioned excessive of the large chainring, taking over the area that the chain will accomodate as soon as the up-shift is full. So, it is smart that the up-shift begins with the outboard rotation of those downshift components away from the tooth of the large chainring.
![sram chainring coupled front derailleur 2x drivetrain down-shift arms in upshift mode](https://bikerumor.com/wp-content/uploads/2023/07/SRAM-Chainring-Derailleur-Concept-patent-patrol_shifting-section-Fig-13-800x762.jpg)
The up-shift driver (yellow), and its connecting hyperlinks (blue), are proven clearly in Fig.13. Because the up-shift driver rotates counter-clockwise, the hyperlinks of the mechanism pull the arms of the down-shift components via a clockwise arc, re-positioning them away from the tooth of the large chainring. That’s step one, which is subsequently adopted by the inboard rotation of the up-shift equipment (inexperienced)… however solely when the timing is true.
![sram chainring derailleur front shift mechanism up-shift apparatus green](https://bikerumor.com/wp-content/uploads/2023/07/SRAM-Chainring-Derailleur-Concept-patent-patrol_inner-view-Fig-41-800x533.jpg)
The up-shift equipment (inexperienced) is simply allowed to fall inwards, slotting the information pegs (inexperienced) via the complementary holes of the large chainring, when the chain is obvious of these holes, i.e. when the chainring has been pedaled right into a place whereby the up-shift equipment is in a rearward place, as proven in Fig. 41.
From right here, the sequence of occasions is kind of intuitive (beneath, Figs. 47-51). In the entire drawings, the small chainring seems to be lacking a tooth. That area is stuffed by the primary information peg of the up-shift equipment (inexperienced) when it rotates inboard. From right here, it is ready to catch maintain of the chain, through the internal floor of an outer plate, as it’s pulled via the pedal stroke.
![sram chainring coupled front derailleur upshift mechansim guide pins transfer chain to big ring](https://bikerumor.com/wp-content/uploads/2023/07/SRAM-Chainring-Derailleur-Concept-patent-patrol_Figs-47-51-upshift-sequence-1-800x576.jpg)
![sram chainring derailleur concept frontshift integrated into crankset guide pins transfer chain from small to big chainring](https://bikerumor.com/wp-content/uploads/2023/07/SRAM-Chainring-Derailleur-Concept-patent-patrol_upshift-pins-Fig-70-800x480.jpg)
Fig. 70 exhibits how every information peg is strategically positioned such that every subsequent one sits barely additional outboard (radially) than its neighbor. The anatomy of these information pegs is crucial to the up-shift mechanism. Figs. 53 & 54 present how every peg (inexperienced) has a tip with a chamfered prime floor (290) that enables the chain to slip down the peg, pulling it additional outboard because it slides.
![sram chainring coupled front derailleur up-shift guide peg anatomy contacts chain outer plate](https://bikerumor.com/wp-content/uploads/2023/07/SRAM-Chainring-Derailleur-Concept-patent-patrol_chain-lifter-section-Figs-53-54-800x410.jpg)
Through the sequence seen beneath in Figs. 47-51, the outer plate of the chain hyperlink (orange) that originally contacts the primary information peg is progressively moved away from the airplane of the small chainring, and into the airplane of the large chainring, with a closing, bigger up-shifting peg finishing the transition. That up-shifting peg (320) then stays in place, thereafter functioning as a daily tooth of the chainring. The big plate (206, burgundy in some drawings) that sits outboard of the large chainring tooth acts as a information to forestall the chain falling off the large ring within the outboard path throughout an up-shift.
The Downshift Mechanism
Now, we take a better have a look at the down-shift mechanism of SRAM’s chainring-coupled entrance derailleur, whereby the chain is transferred from the large chainring to the small chainring. This mechanism shouldn’t be so completely different to how conventional seat-tube mounted entrance derailleurs information the chain off the large chainring towards to airplane of the smaller chainring.
![sram chainring coupled front derailleur down-shift initiation](https://bikerumor.com/wp-content/uploads/2023/07/SRAM-Chainring-Derailleur-Concept-patent-patrol_Fig-13-46-downshift-800x533.jpg)
To mediate a down-shift, the linkage controlling the positioning of the down-shift components (212a and 212b in Crimson) articulates about its varied pivots with a purpose to rotate the down-shift components via a counter-clockwise arc. It strikes from the place proven in Fig. 13, to the place proven in Fig. 46, re-positioning the protruding arms of the down-shift components inboard, to the purpose the place the highest floor (338) overlaps the airplane of the large chainring.
Along with this rotation, the information pegs of the up-shift equipment are concurrently retracted away from the small chainring and again right into a devoted recess throughout the physique of the massive chainring.
![sram chainring coupled front derailleur down-shift elements positioned to initiate derailing of chain from big ring](https://bikerumor.com/wp-content/uploads/2023/07/SRAM-Chainring-Derailleur-Concept-patent-patrol_downshift-paddles-Fig-52-800x640.jpg)
Once more, the timing is essential. A down-shift ingredient will solely have the ability to rotate into the place proven in Fig. 46 when it’s positioned rearward of the chainring. i.e. at a place the place the chain shouldn’t be engaged with the tooth of the large chainring – see Fig. 52. That’s as a result of the presence of the chain on the tooth will bodily stop motion of the down-shift arm into its down-shift place.
![sram chainring coupled front derailleur shift apparatus](https://bikerumor.com/wp-content/uploads/2023/07/SRAM-Chainring-Derailleur-Concept-patent-patrol_downshift-paddles-Fig-59-800x640.jpg)
When the downshift arm is free to rotate inward to a place the place it overlaps the airplane of the large chainring, it’s then able to de-rail the chain off the large chainring. Because the rider continues via the pedal stroke, the chamfered floor (338) of the “main” down-shift arm (212a) contacts the chain, deflecting it out of alignment with the large chainring, and into alignment with the small chainring.
After not more than half a pedal stroke, the chain is picked up by the small chainring. After a full revolution, all hyperlinks of the chain shall be engaged with the tooth of the small chainring, and the down-shift is accomplished.
Is the SRAM Chainring-Coupled Derailleur an Trade First?
SRAM is certainly not the primary model to research options to the standard, seat tube-mounted entrance derailleur. Labeled Biking supply essentially the most sturdy, confirmed answer with their Powershift Hub. By advantage of inside gearing packed away contained in the hub of the rear wheel, the Powershift Hub is ready to supply two distinct gear ratios for each single sprocket of the cassette. So, when you’re working a 12-speed cassette, you even have 24 discrete gears at your disposal.
![Classified Powershift Boost MTB 2x internal gear mountain bike hub for Shimano or SRAM 12-speed, Bike Connection Agency photo by Mirror Media, exploded view](https://bikerumor.com/wp-content/uploads/2023/04/Classified-Powershift-Boost-MTB-2x-internal-gear-mountain-bike-hub-for-Shimano-SRAM-12sp_Mountain-Bike-Connection-Winter_Mirror-Media_exploded-view-800x480.jpg)
Really, this isn’t even the primary time we’ve seen an organization try to combine the entrance shift mechanism into the chainring-crankset meeting. Vyro, an organization that’s seemingly not in existence, tried to convey one thing just like market in 2015.
![vyro amen1 2x drivetrain crankset shift mechanism](https://bikerumor.com/wp-content/uploads/2016/03/Vyro-AmEn1_2x-two-speed-self-shifting-crankset_gearbox-alternative_17_dirty-crank-600x450.jpg)
The Vyro Am En1 cranks, geared toward All-Mountain and Enduro purposes, featured an enormous chainring that was successfully segmented into 4 quarters, every capable of transfer radially outboard independently of each other with a purpose to permit the chain to fall from the large ring to the small ring because the rider pedaled the cranks via a full rotation. It was a neat answer that allowed the rider to shift below load, however in apply there have been some actual points with its sturdiness, and our EU Tech Editor, Cory Benson, had the misfortune of some key part failures whereas testing the system.
![2023 specialized sirrus carbon x compliant frame strut](https://bikerumor.com/wp-content/uploads/2023/03/2023-specialized-sirrus-carbon-strut-frame-compliance-800x533.jpg)
Potential Implications for a Entrance Derailleur That Lives on the Chainrings
The answer proposed by SRAM is kind of completely different to the abovementioned designs, but nonetheless claims to supply higher shifting below load than a conventional seat tube-mounted entrance derailleur. And, it ought to permit body designers the liberty to re-shape the entrance triangle within the data they not want to offer a structural member for the mounting of it.
For some uncommon body designs, just like the Rondo Ruut 2.0 and the 2023 Specialized Sirrus, the implications are clear. Whereas their lack of a suitably-positioned seat tube at the moment prevents them benefiting from a two-chainring crankset, SRAM’s chainring-coupled derailleur appears to be an inexpensive answer.
![2024 Rondo Ruut v2 all-new unique carbon gravel bike, interrupted seattube frame detail](https://bikerumor.com/wp-content/uploads/2023/07/2024-Rondo-Ruut-v2-unique-adjustable-carbon-gravel-bike_up-close-800x533.jpg)
There’s additionally scope right here for an enormous enchancment within the aerodynamic properties of the drivetrain as an entire. Depending on how well-executed that aerodynamic cowl for large chainring is, this might lead to markedly decreased drag as in contrast a entrance derailleur clamped onto the seat tube the place it is extremely uncovered, with the wind hitting it from all angles.
![sram force axs wide review](https://bikerumor.com/wp-content/uploads/2020/05/sram-force-wide-front-derailleur-test-ride-03-800x533.jpg)
Definitely, there appears to be some good arguments for this new entrance shifting mechanism. On prime of these already talked about, this method would absolutely be a lot simpler to arrange than a conventional drivetrain, wouldn’t it? That mentioned, we additionally foresee numerous downsides.
First up, shifting in both path is more likely to be slower than the shifting enabled by present entrance derailleur designs. Per revolution of the crankset, just one alternative is offered for an up-shift, with two alternatives offered for a down-shift.
So, depending on cadence, the rider may expertise a noticeable lag in shift initiation as they await the shift equipment to hit the proper level within the pedal stroke. That compares to common entrance derailleurs that may provoke a shift on demand, the place the lag is successfully depending on the ramps and pins of your chainrings, usually offering 3-5 shift factors per rotation on premium drivetrains.
Additionally, it seems as if it will be very troublesome to execute a modular model of this method whereby chainring sizes may be switched as much as the rider’s choice, and the gradients and elevation profiles in numerous components of the world. We reckon the up-shift mechanism no less than shall be distinctive to a selected pairing of chainring sizes. That’s in distinction to the present crop of entrance derailleurs which supply some extent of adjustability to go well with completely different chainring sizes and combos.
Then, there’s the query of sturdiness. As proven, giant parts of the up-shift and down-shift mechanism shall be uncovered to moisture, in addition to filth and dirt from the street floor. That’s the case with any derailleur after all, however this mechanism does function numerous pivots which might be all susceptible to untimely put on if the system isn’t sufficiently sealed.
Additionally, these down-shift parts are going to see a substantial quantity of grime kicked up from the entrance tire via each single rotation of the crank, and I don’t think about any of it will likely be a stroll within the park to scrub.
Lastly, I do marvel how Q-Issue could be impacted by the housing of all that infrastructure on the large chainring. It appears attainable the design may require a barely wider Q-Issue, which can be an undesirable function for some riders.
Equally, for these liable to heel rub points, the extra actual property packed beneath an outboard cowl on the chainring may pose additional subject with clearance all through the pedal stroke. Definitely, the clocking of the parts and their packaging would wish to think about this very fastidiously.
Hypotheses apart, we’ll not be able to completely perceive any of the above until SRAM can, and even need to, execute on this design.
We have now reached out to study of their plans for this new shifting expertise, but it surely’s a “no remark” for now. In fact, a patent serves solely to guard the inventors’ concepts from implementation by rivals; it doesn’t imply SRAM really plan to convey this chainring-coupled entrance derailleur to market, nor does it essentially imply they also have a working prototype.
I’m prepared to wager they do, although. We predict this can be a cool thought from SRAM, and wouldn’t be shocked in the event that they ultimately introduced this, or one thing very related, to market over the following few years. Even when it by no means sees the sunshine of day, it’s all the time tremendous attention-grabbing to see what the brains behind the large manufacturers are engaged on behind the scenes.
[ad_2]