Campagnolo Super Record Ultra Torque 12Sp ChainsetA super-lightweight and high-quality chainset, engineered to take your riding to the next level.Amazingly Light and Robust Road chainsetThe Super Record UltraTorque chainset (12Sp) from Campagnolo has been specially designed with the thrill-seekers in mind for a faster and more stable shifting experience when out on the road. Made from carbon fibre which is not only ultra-lightweight but also ultra-tough for years of long-lasting use.Equipped with the Ultra-Torque bracket system with a titanium axle which allows you to transfer all your pedalling power directly into the drivetrain for a faster gliding experience. By using ceramic Cult bearings, you'll notice how impressively smooth rolling your bike becomes when out on the road. The newly designed outer chainring guarantees a faster, quieter derailing experience thanks to the contoured pin while the symmetrical design of the inner chainring teeth proves more enhanced stability and control during chain crossovers.The Campagnolo Super Record UltraTorque chainset (12Sp) is the perfect choice for keeping you at the top of your game, whether you're competing or cycling for leisure.Features: Material: Carbon Fibre Length: 165; 170; 172.5; 175mm Combinations 39/53 - 36/52 - 34/50 Ultra-Torque bracket system with a titanium axle Aerodynamic super design Ceramic Cult bearings Unchanged Q Factor (145.5) Symmetrical inner chainring teeth Optimised design for every chainring combination. Ceramic Cult bearings Weight 0.618kg Buy Campagnolo Components from Chain Reaction Cycles, the World's Largest Online Bike Store.
Campagnolo Record Ultra Torque 12 Speed ChainsetA high quality and durable chainset featuring a new hole-free design for the right-hand crank that optimises aerodynamics. The Record Ultra Torque chainset (12 Sp) from Campagnolo comes fully equipped with state-of-the art technology that will keep your bike running in peak condition.Powerful and Faster than beforeThe Ultra-Torque bracket system located on the steel axle ensures the perfect transmission of power, so you can soar past your competitors when out on the road. This chainset can be installed on any type of frame and doesn't have to have disc brakes fitted due to it optimising the chain line of your frame with a rear hub flange measuring 130, 135 or 142mm while the Q factor remains constant at 145.5mm.The Record Ultra boasts an impressive new outer chainring design which guarantees faster and quieter derailing thanks to the contoured pin. The symmetrical construction on the inner chainring teeth adds more improved stability with chain crossovers than ever before.The Campagnolo Record Ultra Torque chainset (12 Sp) is the perfect choice for keeping you at the top of your game when out on the road.Features: New design, same dimensions: Compatible with all frame systems, regardless of the width of the rear chainstay. Unchanged Q Factor (145.5): Both the dimensions and the pedalling biodynamics remain unchanged. Unidirectional carbon fibre hand cranks, steel axle and aluminium chainrings: Substantial stiffness and excellent power transfer. Symmetrical inner chainring teeth: Fluid and precise drivetrain, even with the greater crossovers. Optimised design for every chainring combination: Maximum performance, always. Double wheel sizing standards: Improved system stiffness and reduced weight due to increased use of carbon fibre. Superficial treatment of the chainrings for a longer lifespan Buy Campagnolo Components from Chain Reaction Cycles, the World's Largest Online Bike Store.
Campagnolo Record Ultra Torque 12 Speed ChainsetA high quality and durable chainset featuring a new hole-free design for the right-hand crank that optimises aerodynamics. The Record Ultra Torque chainset (12 Sp) from Campagnolo comes fully equipped with state-of-the art technology that will keep your bike running in peak condition.Powerful and Faster than beforeThe Ultra-Torque bracket system located on the steel axle ensures the perfect transmission of power, so you can soar past your competitors when out on the road. This chainset can be installed on any type of frame and doesn't have to have disc brakes fitted due to it optimising the chain line of your frame with a rear hub flange measuring 130, 135 or 142mm while the Q factor remains constant at 145.5mm.The Record Ultra boasts an impressive new outer chainring design which guarantees faster and quieter derailing thanks to the contoured pin. The symmetrical construction on the inner chainring teeth adds more improved stability with chain crossovers than ever before.The Campagnolo Record Ultra Torque chainset (12 Sp) is the perfect choice for keeping you at the top of your game when out on the road.Features: New design, same dimensions: Compatible with all frame systems, regardless of the width of the rear chainstay. Unchanged Q Factor (145.5): Both the dimensions and the pedalling biodynamics remain unchanged. Unidirectional carbon fibre hand cranks, steel axle and aluminium chainrings: Substantial stiffness and excellent power transfer. Symmetrical inner chainring teeth: Fluid and precise drivetrain, even with the greater crossovers. Optimised design for every chainring combination: Maximum performance, always. Double wheel sizing standards: Improved system stiffness and reduced weight due to increased use of carbon fibre. Superficial treatment of the chainrings for a longer lifespan Buy Campagnolo Components from Chain Reaction Cycles, the World's Largest Online Bike Store.
Campagnolo Record Ultra Torque 12 Speed ChainsetA high quality and durable chainset featuring a new hole-free design for the right-hand crank that optimises aerodynamics. The Record Ultra Torque chainset (12 Sp) from Campagnolo comes fully equipped with state-of-the art technology that will keep your bike running in peak condition.Powerful and Faster than beforeThe Ultra-Torque bracket system located on the steel axle ensures the perfect transmission of power, so you can soar past your competitors when out on the road. This chainset can be installed on any type of frame and doesn't have to have disc brakes fitted due to it optimising the chain line of your frame with a rear hub flange measuring 130, 135 or 142mm while the Q factor remains constant at 145.5mm.The Record Ultra boasts an impressive new outer chainring design which guarantees faster and quieter derailing thanks to the contoured pin. The symmetrical construction on the inner chainring teeth adds more improved stability with chain crossovers than ever before.The Campagnolo Record Ultra Torque chainset (12 Sp) is the perfect choice for keeping you at the top of your game when out on the road.Features: New design, same dimensions: Compatible with all frame systems, regardless of the width of the rear chainstay. Unchanged Q Factor (145.5): Both the dimensions and the pedalling biodynamics remain unchanged. Unidirectional carbon fibre hand cranks, steel axle and aluminium chainrings: Substantial stiffness and excellent power transfer. Symmetrical inner chainring teeth: Fluid and precise drivetrain, even with the greater crossovers. Optimised design for every chainring combination: Maximum performance, always. Double wheel sizing standards: Improved system stiffness and reduced weight due to increased use of carbon fibre. Superficial treatment of the chainrings for a longer lifespan Buy Campagnolo Components from Chain Reaction Cycles, the World's Largest Online Bike Store.
Campagnolo Ekar 13 Speed Single Gravel ChainsetStiff, elegant and created for optimum power transfer over challenging terrain, Campagnolo’s 1x13-Speed Ekar chainset boasts carbon fibre crank arms for a low weight with high strength. It combines with the Ekar system to bring you the range, efficiency, durability and chain retention you need to thrive off-road.Gravel Bike ChainsetThe 1x chainset is a crucial element in Campagnolo's gravel & all-road specific Ekar drivetrain design. Lightweight, secure and simple, with no wasted overlapping gears or unnecessary moving parts to collect trail dirt. The Ekar chainset will convince you that one chainring and no front mech is the way to go, whatever your off-road ambitions!Strong Carbon Fibre Crank ArmsDon’t let the apparent simplicity fool you, this chainset has been designed from the ground up. Just like the whole Ekar system, the cranks combine strength and lightweight materials. The 2-piece crankset features a strong, durable 630-grade steel alloy axle mated to a polyamide-carbon spider and beautiful UD Carbon arms. The ergonomics of this chainset mean it is suitable for any size of rider, with 4 crank arm lengths available. The outer chainrings are also easily interchangeable, with no need to disassemble the chainset if you want to alter your gearing.Features: Material: UD Carbon Fibre crank arms, polyamide-carbon spider and Ultra-Torque 630 Steel axle Speed: 1x13-Speed Recommended Chain: Campagnolo Ekar 13-speed Axle Profile: Ultra-Torque integrated axle Designed specifically for Ekar 1x13 groupsets Suitable for Gravel and All-Road riding Crank boots included to protect the crank arms Easily interchangeable chainrings Easy access external bearings Narrow-wide chainring tooth for design efficient drive & maximum chain security Easily interchangeable alloy rings - no need to disassemble crank Narrow Q-Factor of 145.5mm ensures compatibility with all modern frames Bottom bracket cups not included Weight: 615g (based on 172.5mm, 38T)Technologies: Pro-Tech: Patented dual-sealing ProTech technology securely connects the two semi-axles inside the bottom bracket and protects the BB bearings from ingress of water and mud, providing longevity of high performance, even in the worst riding conditions. A gravel-orientated development from Campagnolo's innovative and proven Ultra-Torque technology, the ProTech system's central Hirth joint features self-centring and self-aligning frontal teeth located in the middle of the crank where the ends of the integrated semi-axles meet. Buy Campagnolo Components from Chain Reaction Cycles, the World's Largest Online Bike Store.
Campagnolo Ekar 13 Speed Single Gravel ChainsetStiff, elegant and created for optimum power transfer over challenging terrain, Campagnolo’s 1x13-Speed Ekar chainset boasts carbon fibre crank arms for a low weight with high strength. It combines with the Ekar system to bring you the range, efficiency, durability and chain retention you need to thrive off-road.Gravel Bike ChainsetThe 1x chainset is a crucial element in Campagnolo's gravel & all-road specific Ekar drivetrain design. Lightweight, secure and simple, with no wasted overlapping gears or unnecessary moving parts to collect trail dirt. The Ekar chainset will convince you that one chainring and no front mech is the way to go, whatever your off-road ambitions!Strong Carbon Fibre Crank ArmsDon’t let the apparent simplicity fool you, this chainset has been designed from the ground up. Just like the whole Ekar system, the cranks combine strength and lightweight materials. The 2-piece crankset features a strong, durable 630-grade steel alloy axle mated to a polyamide-carbon spider and beautiful UD Carbon arms. The ergonomics of this chainset mean it is suitable for any size of rider, with 4 crank arm lengths available. The outer chainrings are also easily interchangeable, with no need to disassemble the chainset if you want to alter your gearing.Features: Material: UD Carbon Fibre crank arms, polyamide-carbon spider and Ultra-Torque 630 Steel axle Speed: 1x13-Speed Recommended Chain: Campagnolo Ekar 13-speed Axle Profile: Ultra-Torque integrated axle Designed specifically for Ekar 1x13 groupsets Suitable for Gravel and All-Road riding Crank boots included to protect the crank arms Easily interchangeable chainrings Easy access external bearings Narrow-wide chainring tooth for design efficient drive & maximum chain security Easily interchangeable alloy rings - no need to disassemble crank Narrow Q-Factor of 145.5mm ensures compatibility with all modern frames Bottom bracket cups not included Weight: 615g (based on 172.5mm, 38T)Technologies: Pro-Tech: Patented dual-sealing ProTech technology securely connects the two semi-axles inside the bottom bracket and protects the BB bearings from ingress of water and mud, providing longevity of high performance, even in the worst riding conditions. A gravel-orientated development from Campagnolo's innovative and proven Ultra-Torque technology, the ProTech system's central Hirth joint features self-centring and self-aligning frontal teeth located in the middle of the crank where the ends of the integrated semi-axles meet. Buy Campagnolo Components from Chain Reaction Cycles, the World's Largest Online Bike Store.
Campagnolo Ekar 13 Speed Single Gravel ChainsetStiff, elegant and created for optimum power transfer over challenging terrain, Campagnolo’s 1x13-Speed Ekar chainset boasts carbon fibre crank arms for a low weight with high strength. It combines with the Ekar system to bring you the range, efficiency, durability and chain retention you need to thrive off-road.Gravel Bike ChainsetThe 1x chainset is a crucial element in Campagnolo's gravel & all-road specific Ekar drivetrain design. Lightweight, secure and simple, with no wasted overlapping gears or unnecessary moving parts to collect trail dirt. The Ekar chainset will convince you that one chainring and no front mech is the way to go, whatever your off-road ambitions!Strong Carbon Fibre Crank ArmsDon’t let the apparent simplicity fool you, this chainset has been designed from the ground up. Just like the whole Ekar system, the cranks combine strength and lightweight materials. The 2-piece crankset features a strong, durable 630-grade steel alloy axle mated to a polyamide-carbon spider and beautiful UD Carbon arms. The ergonomics of this chainset mean it is suitable for any size of rider, with 4 crank arm lengths available. The outer chainrings are also easily interchangeable, with no need to disassemble the chainset if you want to alter your gearing.Features: Material: UD Carbon Fibre crank arms, polyamide-carbon spider and Ultra-Torque 630 Steel axle Speed: 1x13-Speed Recommended Chain: Campagnolo Ekar 13-speed Axle Profile: Ultra-Torque integrated axle Designed specifically for Ekar 1x13 groupsets Suitable for Gravel and All-Road riding Crank boots included to protect the crank arms Easily interchangeable chainrings Easy access external bearings Narrow-wide chainring tooth for design efficient drive & maximum chain security Easily interchangeable alloy rings - no need to disassemble crank Narrow Q-Factor of 145.5mm ensures compatibility with all modern frames Bottom bracket cups not included Weight: 615g (based on 172.5mm, 38T)Technologies: Pro-Tech: Patented dual-sealing ProTech technology securely connects the two semi-axles inside the bottom bracket and protects the BB bearings from ingress of water and mud, providing longevity of high performance, even in the worst riding conditions. A gravel-orientated development from Campagnolo's innovative and proven Ultra-Torque technology, the ProTech system's central Hirth joint features self-centring and self-aligning frontal teeth located in the middle of the crank where the ends of the integrated semi-axles meet. Buy Campagnolo Components from Chain Reaction Cycles, the World's Largest Online Bike Store.
Campagnolo Ekar 13 Speed Single Gravel ChainsetStiff, elegant and created for optimum power transfer over challenging terrain, Campagnolo’s 1x13-Speed Ekar chainset boasts carbon fibre crank arms for a low weight with high strength. It combines with the Ekar system to bring you the range, efficiency, durability and chain retention you need to thrive off-road.Gravel Bike ChainsetThe 1x chainset is a crucial element in Campagnolo's gravel & all-road specific Ekar drivetrain design. Lightweight, secure and simple, with no wasted overlapping gears or unnecessary moving parts to collect trail dirt. The Ekar chainset will convince you that one chainring and no front mech is the way to go, whatever your off-road ambitions!Strong Carbon Fibre Crank ArmsDon’t let the apparent simplicity fool you, this chainset has been designed from the ground up. Just like the whole Ekar system, the cranks combine strength and lightweight materials. The 2-piece crankset features a strong, durable 630-grade steel alloy axle mated to a polyamide-carbon spider and beautiful UD Carbon arms. The ergonomics of this chainset mean it is suitable for any size of rider, with 4 crank arm lengths available. The outer chainrings are also easily interchangeable, with no need to disassemble the chainset if you want to alter your gearing.Features: Material: UD Carbon Fibre crank arms, polyamide-carbon spider and Ultra-Torque 630 Steel axle Speed: 1x13-Speed Recommended Chain: Campagnolo Ekar 13-speed Axle Profile: Ultra-Torque integrated axle Designed specifically for Ekar 1x13 groupsets Suitable for Gravel and All-Road riding Crank boots included to protect the crank arms Easily interchangeable chainrings Easy access external bearings Narrow-wide chainring tooth for design efficient drive & maximum chain security Easily interchangeable alloy rings - no need to disassemble crank Narrow Q-Factor of 145.5mm ensures compatibility with all modern frames Bottom bracket cups not included Weight: 615g (based on 172.5mm, 38T)Technologies: Pro-Tech: Patented dual-sealing ProTech technology securely connects the two semi-axles inside the bottom bracket and protects the BB bearings from ingress of water and mud, providing longevity of high performance, even in the worst riding conditions. A gravel-orientated development from Campagnolo's innovative and proven Ultra-Torque technology, the ProTech system's central Hirth joint features self-centring and self-aligning frontal teeth located in the middle of the crank where the ends of the integrated semi-axles meet. Buy Campagnolo Components from Chain Reaction Cycles, the World's Largest Online Bike Store.
Campagnolo Chorus 12 Speed Ultra Torque ChainsetFeaturing high-quality carbon fibre crank arms, this 12 speed chainset offers excellent stiffness, durability and low weight performance for the demands of road cycling. Thanks to this model's carbon fibre build, it delivers a smooth and responsive pedal stroke without adding any unnecessary excess grams to your ride. Campagnolo has also equipped this model with a robust steel Ultra Torque axle and two aluminium chainrings for fantastic strength and reliability, wherever your next road journey takes you. Suitable for use with disc or rim brake groupsets, this chainset's chainrings also benefit from a special surface treatment for increased longevity.Carbon Fibre 12 Speed Road ChainsetThe updated Chorus chainset is a true concentrate of technology and versatility. Technically advanced thanks to unidirectional construction technology in carbon fibre, it is directly moulded without any surface coating and has an Ultra-Torque steel axle like the Record chainset. The revised 12x cranks are more versatile thanks to the bolt PCD of 123mm, giving it an extremely solid structure, also ensuring a wider variety of uses. The smaller bolt circle on the Chorus chainset makes it compatible with 36/52, 34/50 and the brand new 32/48 ratio chainrings (options available to select from the menu).Features: Crank Arm Material: Carbon Fibre Chainrings Material: Aluminium Axle Material: Steel Ultra Torque axle Use: Road Speed: 12 Speed Q Factor: 145.5mm Bolt: 4-bolt Brake Compatibility: For use with the disc or rim brake groupsets Weight: 718g (172.5mm, 34/50T Option)Technologies: The Q Factor remains the same (145.5mm): The widths and biodynamics of the stroke are the same. Unidirectional carbon fibre cranks, steel axle and aluminium chainrings: Good stiffness and optimum power transmission. Symmetrical teeth on the internal chainring: Fluid, precise transmission, even with extreme cross-chaining.The Q Factor remains the same (145.5mm): The widths and biodynamics of the stroke are the same. Optimised design for any chainring combination: Maximum performance, whatever the course style. Double Fixing: Assembly of the large chainring onto the crank is secured by a ring of 123mm bolts, while the inner chainring is attached to the outer by way of 96mm PCD bolts. Surface treatment of the chainrings for longer life. 12x Chorus Ultra-Torque chainset for use with the disc or rim brake groupset.Manufacturer's Part Numbers: CPB820A Black Carbon 170mm 32/48T CPB820B Black Carbon 170mm 34/50T CPB820C Black Carbon 170mm 36/52T CPB821A Black Carbon 172.5mm 32/48T CPB821B Black Carbon 172.5mm 34/50T CPB821C Black Carbon 172.5mm 36/52T CPB822A Black Carbon 175mm 32/48T CPB822B Black Carbon 175mm 34/50T CPB822C Black Carbon 175mm 36/52TBuy Campagnolo Components from Chain Reaction Cycles, the World's Largest Online Bike Store.
Campagnolo Chorus 12 Speed Ultra Torque ChainsetFeaturing high-quality carbon fibre crank arms, this 12 speed chainset offers excellent stiffness, durability and low weight performance for the demands of road cycling. Thanks to this model's carbon fibre build, it delivers a smooth and responsive pedal stroke without adding any unnecessary excess grams to your ride. Campagnolo has also equipped this model with a robust steel Ultra Torque axle and two aluminium chainrings for fantastic strength and reliability, wherever your next road journey takes you. Suitable for use with disc or rim brake groupsets, this chainset's chainrings also benefit from a special surface treatment for increased longevity.Carbon Fibre 12 Speed Road ChainsetThe updated Chorus chainset is a true concentrate of technology and versatility. Technically advanced thanks to unidirectional construction technology in carbon fibre, it is directly moulded without any surface coating and has an Ultra-Torque steel axle like the Record chainset. The revised 12x cranks are more versatile thanks to the bolt PCD of 123mm, giving it an extremely solid structure, also ensuring a wider variety of uses. The smaller bolt circle on the Chorus chainset makes it compatible with 36/52, 34/50 and the brand new 32/48 ratio chainrings (options available to select from the menu).Features: Crank Arm Material: Carbon Fibre Chainrings Material: Aluminium Axle Material: Steel Ultra Torque axle Use: Road Speed: 12 Speed Q Factor: 145.5mm Bolt: 4-bolt Brake Compatibility: For use with the disc or rim brake groupsets Weight: 718g (172.5mm, 34/50T Option)Technologies: The Q Factor remains the same (145.5mm): The widths and biodynamics of the stroke are the same. Unidirectional carbon fibre cranks, steel axle and aluminium chainrings: Good stiffness and optimum power transmission. Symmetrical teeth on the internal chainring: Fluid, precise transmission, even with extreme cross-chaining.The Q Factor remains the same (145.5mm): The widths and biodynamics of the stroke are the same. Optimised design for any chainring combination: Maximum performance, whatever the course style. Double Fixing: Assembly of the large chainring onto the crank is secured by a ring of 123mm bolts, while the inner chainring is attached to the outer by way of 96mm PCD bolts. Surface treatment of the chainrings for longer life. 12x Chorus Ultra-Torque chainset for use with the disc or rim brake groupset.Manufacturer's Part Numbers: CPB820A Black Carbon 170mm 32/48T CPB820B Black Carbon 170mm 34/50T CPB820C Black Carbon 170mm 36/52T CPB821A Black Carbon 172.5mm 32/48T CPB821B Black Carbon 172.5mm 34/50T CPB821C Black Carbon 172.5mm 36/52T CPB822A Black Carbon 175mm 32/48T CPB822B Black Carbon 175mm 34/50T CPB822C Black Carbon 175mm 36/52TBuy Campagnolo Components from Chain Reaction Cycles, the World's Largest Online Bike Store.
Campagnolo Chorus 12 Speed Ultra Torque ChainsetFeaturing high-quality carbon fibre crank arms, this 12 speed chainset offers excellent stiffness, durability and low weight performance for the demands of road cycling. Thanks to this model's carbon fibre build, it delivers a smooth and responsive pedal stroke without adding any unnecessary excess grams to your ride. Campagnolo has also equipped this model with a robust steel Ultra Torque axle and two aluminium chainrings for fantastic strength and reliability, wherever your next road journey takes you. Suitable for use with disc or rim brake groupsets, this chainset's chainrings also benefit from a special surface treatment for increased longevity.Carbon Fibre 12 Speed Road ChainsetThe updated Chorus chainset is a true concentrate of technology and versatility. Technically advanced thanks to unidirectional construction technology in carbon fibre, it is directly moulded without any surface coating and has an Ultra-Torque steel axle like the Record chainset. The revised 12x cranks are more versatile thanks to the bolt PCD of 123mm, giving it an extremely solid structure, also ensuring a wider variety of uses. The smaller bolt circle on the Chorus chainset makes it compatible with 36/52, 34/50 and the brand new 32/48 ratio chainrings (options available to select from the menu).Features: Crank Arm Material: Carbon Fibre Chainrings Material: Aluminium Axle Material: Steel Ultra Torque axle Use: Road Speed: 12 Speed Q Factor: 145.5mm Bolt: 4-bolt Brake Compatibility: For use with the disc or rim brake groupsets Weight: 718g (172.5mm, 34/50T Option)Technologies: The Q Factor remains the same (145.5mm): The widths and biodynamics of the stroke are the same. Unidirectional carbon fibre cranks, steel axle and aluminium chainrings: Good stiffness and optimum power transmission. Symmetrical teeth on the internal chainring: Fluid, precise transmission, even with extreme cross-chaining.The Q Factor remains the same (145.5mm): The widths and biodynamics of the stroke are the same. Optimised design for any chainring combination: Maximum performance, whatever the course style. Double Fixing: Assembly of the large chainring onto the crank is secured by a ring of 123mm bolts, while the inner chainring is attached to the outer by way of 96mm PCD bolts. Surface treatment of the chainrings for longer life. 12x Chorus Ultra-Torque chainset for use with the disc or rim brake groupset.Manufacturer's Part Numbers: CPB820A Black Carbon 170mm 32/48T CPB820B Black Carbon 170mm 34/50T CPB820C Black Carbon 170mm 36/52T CPB821A Black Carbon 172.5mm 32/48T CPB821B Black Carbon 172.5mm 34/50T CPB821C Black Carbon 172.5mm 36/52T CPB822A Black Carbon 175mm 32/48T CPB822B Black Carbon 175mm 34/50T CPB822C Black Carbon 175mm 36/52TBuy Campagnolo Components from Chain Reaction Cycles, the World's Largest Online Bike Store.
Taking many features from pro-level equipment this 2-piece cap-free design Tiagra chainset offers unbeatable performance2-piece cap-free design is quick and easy to install whilst being lighter and stiffer than a traditional crank/ bottom bracket assemblySG-X chainrings feature strategically placed chain pick-up pins and tooth profiles to ensure fast and positive shiftingDesigned to work with HollowTech II type bottom bracket cupsCompatible with 10-speed HG-X chainsAnodized aluminium crank armsLightweight aluminium chainrings4 arm 110 mm bolt circle diameter