Periodic Reporting for period 2 - SEGSEQ (Segmented Chainring for Sequential Shifting in Bicycles)
Okres sprawozdawczy: 2021-09-01 do 2023-01-31
The bicycle is the most effective non-assisted form of displacement; thus, it has been extensively used as transportation vehicle, but also as a device for leisure and/or sportive competition. The different gearings in bicycle transmissions allow to comfortably ride on uphill or downhill terrain; indeed, there is a long-standing challenge to get the maximum gear range (large variation between the easiest and hardest gears in order to access a wide set of terrains) with minimum steps between gears (small variation between consecutive gears in order to adjust for a more consistent and efficient pedalling), i.e. the maximum number of effectively usable gear combinations is sought.
Since parallelogram derailleurs were introduced in the 1950’s, little changes have been observed in bicycle transmission technology. Even the most recent electronic derailleurs use the same parallelogram mechanism, just substituting the cable actuation by a motor actuation. There were high expectations that electronic shifting would bring sequential shifting, i.e. instead of the rider deciding whether to shift sprockets or chainring, a simple “harder” or “easier” transmission command would be provided, and the system would automatically operate on the corresponding sprockets or chainring, but it never happened.
The main challenge for improved gearing at present is still mechanical, as it was the case 60 years ago; i.e. pedalling force must necessarily be reduced if a front shift is going to be performed. The physics behind this issue are unavoidable: applying force on the pedals originates tension on the chain at the point where it engages the chainring, generating a downforce that keeps the chain firmly engaged. This is counterproductive for chainring shifting where a lateral force is applied by the front derailleur to disengage the chain in the upward direction and laterally displace it. In current transmissions, even when the chain is displaced under moderate tension, shifting results in high friction and is abrupt, and requires a high-powered motor to exert the necessary shifting force.
Therefore, as the problem is generated by trying to move the tensioned chain towards the chainring, the solution can be as simple as moving the non-tensioned chainring towards the chain. On the contrary, SEGSEQ segments can be displaced with no friction by low-powered actuators while they are on the “chain-free zone”, and they smoothly engage with the chain as pedalling rotation progresses. In this manner, the benefits of a smooth and reliable shifter can be fully exploited: shifting can be applied more often so that wide range and close-step transmissions can be designed for better performance. Also, as shifting is smooth during any situation (even under high pedalling loads), sequential or even automatic shifting are straightforward to implement for unprecedent ease-of-use.
Since parallelogram derailleurs were introduced in the 1950’s, little changes have been observed in bicycle transmission technology. Even the most recent electronic derailleurs use the same parallelogram mechanism, just substituting the cable actuation by a motor actuation. There were high expectations that electronic shifting would bring sequential shifting, i.e. instead of the rider deciding whether to shift sprockets or chainring, a simple “harder” or “easier” transmission command would be provided, and the system would automatically operate on the corresponding sprockets or chainring, but it never happened.
The main challenge for improved gearing at present is still mechanical, as it was the case 60 years ago; i.e. pedalling force must necessarily be reduced if a front shift is going to be performed. The physics behind this issue are unavoidable: applying force on the pedals originates tension on the chain at the point where it engages the chainring, generating a downforce that keeps the chain firmly engaged. This is counterproductive for chainring shifting where a lateral force is applied by the front derailleur to disengage the chain in the upward direction and laterally displace it. In current transmissions, even when the chain is displaced under moderate tension, shifting results in high friction and is abrupt, and requires a high-powered motor to exert the necessary shifting force.
Therefore, as the problem is generated by trying to move the tensioned chain towards the chainring, the solution can be as simple as moving the non-tensioned chainring towards the chain. On the contrary, SEGSEQ segments can be displaced with no friction by low-powered actuators while they are on the “chain-free zone”, and they smoothly engage with the chain as pedalling rotation progresses. In this manner, the benefits of a smooth and reliable shifter can be fully exploited: shifting can be applied more often so that wide range and close-step transmissions can be designed for better performance. Also, as shifting is smooth during any situation (even under high pedalling loads), sequential or even automatic shifting are straightforward to implement for unprecedent ease-of-use.
The main focus of the project has been on mechanical and electronic development of the system, including the proprietary SEGSEQ chainring, as well as all necessary systems (rear derailleur, cassette, cranks, levers, as well as custom electronics and communication) in order to achieve a highly efficient gear shifting groupset. Product development has been structured around several consecutive iterative design loops. The original "concept prototype” has evolved to a more refined “functional system” initially, a “road-ready system" afterwards and a "race-ready system" more recently. Then the system has been pilot tested with an Elite category cycling team in order to evaluate its performance against benchmark products in the market.
The project is organized in 3 work-packages:
The objective of WP1 is to develop the SEGSEQ groupset up to the required functional and quality requirements in the high-end road groupset market up to TRL7. Taking as a basis the original concept prototype, its weak points and main improvement areas were identified and further developed. To assist this process, several ad-hoc developed computational tools were used for allowing exploration of multiple designs so that the trial-error stage could be reduced. Some areas of work were:
Improved contact mechanics for optimal force transmission from segments to small chainring; improved guiding for avoiding segments getting stuck in the engaged position if activated under certain conditions (with vibrations, etc.); actuator development by evaluating different micromotor actuators with a laser-based position sensor and an internally developed monitoring system; construction of a static test-bench for structurally evaluating the developed prototypes; construction of a dynamic test-bench for emulating riding scenarios systematically in the lab; cassette development with new sprocket profiling technology for smoother shifts, as well as optimal synchronization of adjacent sprockets; development of a proprietary solution for the rear derailleur with advantages in terms of manufacturing, assembly, maintenance and product support.
The objective of WP2 is to evolve the Road-ready system developed in WP1 into a more robust and manufacturable system, in order to prepare it towards the industrialization stage.
The computational design tools developed in WP1 were adapted to consider additional restrictions until reaching a satisfactory outcome in all aspects, mainly: reduce chainring volume and improve aesthetics; and place all guiding and actuation elements in an auxiliary unit with flexible mounting access and advantages in sealing and fabrication aspects. Also, several manufacturing improvements were considered in all elements. Additionally, sealing elements were introduced in the guiding link area so that it can be protected from the environment.
The objective of WP3 is to pilot test the SEGSEQ system with an Elite cycling team in order to ensure the product is up to the required functional and quality level.
For optimal data acquisition and insight gathering during pilot tests, the idea of turning each bicycle in a test-bench was pursued. Overall a big potential for the product has been observed, especially with regard to the possibility of gear shifting in any circumstance (sprints, attacks, heavy pedaling) without any power loss, as well as the distinct features related to automatic gear shifting.
The project is organized in 3 work-packages:
The objective of WP1 is to develop the SEGSEQ groupset up to the required functional and quality requirements in the high-end road groupset market up to TRL7. Taking as a basis the original concept prototype, its weak points and main improvement areas were identified and further developed. To assist this process, several ad-hoc developed computational tools were used for allowing exploration of multiple designs so that the trial-error stage could be reduced. Some areas of work were:
Improved contact mechanics for optimal force transmission from segments to small chainring; improved guiding for avoiding segments getting stuck in the engaged position if activated under certain conditions (with vibrations, etc.); actuator development by evaluating different micromotor actuators with a laser-based position sensor and an internally developed monitoring system; construction of a static test-bench for structurally evaluating the developed prototypes; construction of a dynamic test-bench for emulating riding scenarios systematically in the lab; cassette development with new sprocket profiling technology for smoother shifts, as well as optimal synchronization of adjacent sprockets; development of a proprietary solution for the rear derailleur with advantages in terms of manufacturing, assembly, maintenance and product support.
The objective of WP2 is to evolve the Road-ready system developed in WP1 into a more robust and manufacturable system, in order to prepare it towards the industrialization stage.
The computational design tools developed in WP1 were adapted to consider additional restrictions until reaching a satisfactory outcome in all aspects, mainly: reduce chainring volume and improve aesthetics; and place all guiding and actuation elements in an auxiliary unit with flexible mounting access and advantages in sealing and fabrication aspects. Also, several manufacturing improvements were considered in all elements. Additionally, sealing elements were introduced in the guiding link area so that it can be protected from the environment.
The objective of WP3 is to pilot test the SEGSEQ system with an Elite cycling team in order to ensure the product is up to the required functional and quality level.
For optimal data acquisition and insight gathering during pilot tests, the idea of turning each bicycle in a test-bench was pursued. Overall a big potential for the product has been observed, especially with regard to the possibility of gear shifting in any circumstance (sprints, attacks, heavy pedaling) without any power loss, as well as the distinct features related to automatic gear shifting.
During the grant phase of the project, the plan of further developing the system and pilot testing it in cycling competition was achieved. Over ten patents have been pursued to protect developments with several more under preparation.
In the subsequent market deployment stage, it is believed that the disruptive technological proposal of SEGSEQ will introduce several characteristics that cannot be found currently in any product of a market very much monopolized by 2 companies. The system provides performance gains in all metrics: more usable gears, wider gear-range, closer gear-steps, less weight and the possibility to operate shifts in sequential form and even in automatic form using cadence, pedalling power and/or heart-rate feedback.
The final goal is to become the leading technological reference and the European contender to lead the global groupset market.
In the subsequent market deployment stage, it is believed that the disruptive technological proposal of SEGSEQ will introduce several characteristics that cannot be found currently in any product of a market very much monopolized by 2 companies. The system provides performance gains in all metrics: more usable gears, wider gear-range, closer gear-steps, less weight and the possibility to operate shifts in sequential form and even in automatic form using cadence, pedalling power and/or heart-rate feedback.
The final goal is to become the leading technological reference and the European contender to lead the global groupset market.