Best BB30 bearings ?
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Not necessarily. They are designed to deal with side forces, which should be minimal in a BB, so deep grove radial bearings should perform just as well. And you have to make sure you have the correct preload, something not at issue with deep groove radial bearings. But they are better for dealing with misalignments, which BB30 applications can experience if the frame shell is off; so if you are burning through radial bearings quickly, could be there is a misalignment at play. But all things being well aligned, deep grove bearings operating in a radial space like a BB, should have lower drag. At least as far as I have been able to determine.
#27
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Regarding the second question, any 6806 radial cartridge bearing you are likely to find that isnt an angualr contact bearing is likely to be deep grove. They have deep “raceway groves where the inner and outer rings have circular arcs centered in the middle of the rings. Angular contact bearings have arcs that run at an angle to eachother so contact the balls differently.
I dont know what preload adjustment capability is for hollowgram cranks but you need to be able to make that adjustment for the spacing in AC bearings to be correct. So I would go with radial deep grove bearings if I were using that crank just because thats what Cannondale specs with their stuff.
Last edited by DOS; 10-27-19 at 04:48 PM.
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To be honest, we are getting a bit beyond my expertise here so take this with a grain of salt. But...
Regarding the second question, any 6806 radial cartridge bearing you are likely to find that isnt an angualr contact bearing is likely to be deep grove. They have deep “raceway groves where the inner and outer rings have circular arcs centered in the middle of the rings. Angular contact bearings have arcs that run at an angle to eachother so contact the balls differently.
I dont know what preload adjustment capability is for hollowgram cranks but you need to be able to make that adjustment for the sacing in AC bearings to be correct. So I would go with radial deep grove bearings if I were using that crank just because thats what Cannondale specs with tneir stuff.
Regarding the second question, any 6806 radial cartridge bearing you are likely to find that isnt an angualr contact bearing is likely to be deep grove. They have deep “raceway groves where the inner and outer rings have circular arcs centered in the middle of the rings. Angular contact bearings have arcs that run at an angle to eachother so contact the balls differently.
I dont know what preload adjustment capability is for hollowgram cranks but you need to be able to make that adjustment for the sacing in AC bearings to be correct. So I would go with radial deep grove bearings if I were using that crank just because thats what Cannondale specs with tneir stuff.
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Well in the videos Hambini makes the point that most drag is due to seals. Some bearings have full contact seals, which make contact with the bearing races, and some have noncontact seals. The contact seals are better for keeping crap from getting inside the bearing so are more durable; noncontact create less drag so spin more feely. BBINFINITE’s thing seems to be low drag so I guess they use noncontact seals. Other brands are available in noncontact as well.
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I posted this in the 'Who is Hambini' thread also:
AC bearings can last longer in BB30 applications because they have higher load ratings than radial ball bearings. This is down to the filling method of the radial balls (look up Conrad filling method). So an AC of the same size will have more balls and a higher load rating than a radial bearing. So basically nothing to do with axial loads and/or preload. AC has slight rigidity benefit too as the 'effective centres' of the bearing are further apart. Forces are applied to the bearing where a line drawn through the contact angle bisects the axle centreline. However AC is only effective with fixed mechanical adjustment (e.g.screw thread). If your BB is preloading the bearings with a wavy spring then it wont be an AC under a radial load.
Now if you take a radial bearing with a higher radial clearance (C3) and apply preload it becomes an AC albeit with a low contact angle (typically 10~12deg). A bearing with lower clearance or 'standard' clearance CN will have a lower contact angle when preloaded. So C3 clearance will give you a marginal theoretical benefit but misses the main advantage of an AC which is the higher load rating. However the extra clearance in a C3 can be helpful if the machining of your BB is not very accurate and the two bearing positions are misaligned relative to each other.
OK so now lets have a look at precision bearings. Actually the P classes are ISO (Euro & Asia) and ABEC are ANSI (USA) but they are directly comparable P0 (ABEC-1) is standard then P6,P5,P4 & P2 (ABEC-3,5.7 & 9) are all improvements. Now consider that a BB30 bearing size 6806; the standard clearance, standard precision version of which is rated to run at max 15,000rpm and will do so all day long if so required. Now consider that the main benefit of higher precision bearings comes when you wish to exceed the max speed rating of a 'standard' bearing. Then consider that very few cyclists can get anywhere near a 200rpm cadence (yes that is 1.3% of the available speed capability!) Also higher precision bearings demand higher precision from the mating axle and housing journals so fitting them to standard parts has no benefit at all.
No matter how fast you think you are ALL BEARINGS IN BICYCLES OPERATE AT LOW SPEED. That is also why ceramics offer absolutely no tangible benefits for cyclists.
More than 50% of the drag in an unloaded bearing will come from the seals. This will reduce to less than 50% under load because mechanical drag is proportional to load and seal drag is constant. Now the 50% figure will apply to full contact seals (for example NTN seals have two contact lips at each side - which is why they last so well). This can be reduced by using low friction seals (single contact lip), non-contact seals or metal shields. There is no getting away from the fact that seal drag and sealing efficiency are directly related. As soon as you get any dirt inside a bearing you will massively increase the drag torque. This is down to the tolerances and clearances; again using the BB30 size 6806 as an example a CN version will have a radial clearance of 5~20microns (1 micron = 0.001mm) the C3 version 13~28microns. Now consider that a human hair has an thickness somewhere between 50 and 250microns; probably best to keep your helmet and shorts on when servicing your bearings!
If you want to give your cartridge bearings the best start in life try running them in before you fit them. Because bicycle application speeds are so slow the correct grease distribution does not happen. Therefore fix up your electric drill to spin them for 10 minutes at a few thousand rpm. This will help distribute the grease which has many benefits; reduced drag in bearing and seal, improved sealing efficiency, better corrosion protection & better lubrication.
Apologies if this is a bit heavy going but hopefully some of you will understand the key points here. Regarding the OP question any quality bearing is preferable SKF,***,NSK,NTN. Note that in terms of sealing efficiency the NTN full contact seals have a 2 lips on each side (NTN suffix LLU). These are by far the best options for keeping dirt out in my experience. You can halve the seal drag by removing the inboard seal if the BB housing bore has no access holes from the frame tubes.
AC bearings can last longer in BB30 applications because they have higher load ratings than radial ball bearings. This is down to the filling method of the radial balls (look up Conrad filling method). So an AC of the same size will have more balls and a higher load rating than a radial bearing. So basically nothing to do with axial loads and/or preload. AC has slight rigidity benefit too as the 'effective centres' of the bearing are further apart. Forces are applied to the bearing where a line drawn through the contact angle bisects the axle centreline. However AC is only effective with fixed mechanical adjustment (e.g.screw thread). If your BB is preloading the bearings with a wavy spring then it wont be an AC under a radial load.
Now if you take a radial bearing with a higher radial clearance (C3) and apply preload it becomes an AC albeit with a low contact angle (typically 10~12deg). A bearing with lower clearance or 'standard' clearance CN will have a lower contact angle when preloaded. So C3 clearance will give you a marginal theoretical benefit but misses the main advantage of an AC which is the higher load rating. However the extra clearance in a C3 can be helpful if the machining of your BB is not very accurate and the two bearing positions are misaligned relative to each other.
OK so now lets have a look at precision bearings. Actually the P classes are ISO (Euro & Asia) and ABEC are ANSI (USA) but they are directly comparable P0 (ABEC-1) is standard then P6,P5,P4 & P2 (ABEC-3,5.7 & 9) are all improvements. Now consider that a BB30 bearing size 6806; the standard clearance, standard precision version of which is rated to run at max 15,000rpm and will do so all day long if so required. Now consider that the main benefit of higher precision bearings comes when you wish to exceed the max speed rating of a 'standard' bearing. Then consider that very few cyclists can get anywhere near a 200rpm cadence (yes that is 1.3% of the available speed capability!) Also higher precision bearings demand higher precision from the mating axle and housing journals so fitting them to standard parts has no benefit at all.
No matter how fast you think you are ALL BEARINGS IN BICYCLES OPERATE AT LOW SPEED. That is also why ceramics offer absolutely no tangible benefits for cyclists.
More than 50% of the drag in an unloaded bearing will come from the seals. This will reduce to less than 50% under load because mechanical drag is proportional to load and seal drag is constant. Now the 50% figure will apply to full contact seals (for example NTN seals have two contact lips at each side - which is why they last so well). This can be reduced by using low friction seals (single contact lip), non-contact seals or metal shields. There is no getting away from the fact that seal drag and sealing efficiency are directly related. As soon as you get any dirt inside a bearing you will massively increase the drag torque. This is down to the tolerances and clearances; again using the BB30 size 6806 as an example a CN version will have a radial clearance of 5~20microns (1 micron = 0.001mm) the C3 version 13~28microns. Now consider that a human hair has an thickness somewhere between 50 and 250microns; probably best to keep your helmet and shorts on when servicing your bearings!
If you want to give your cartridge bearings the best start in life try running them in before you fit them. Because bicycle application speeds are so slow the correct grease distribution does not happen. Therefore fix up your electric drill to spin them for 10 minutes at a few thousand rpm. This will help distribute the grease which has many benefits; reduced drag in bearing and seal, improved sealing efficiency, better corrosion protection & better lubrication.
Apologies if this is a bit heavy going but hopefully some of you will understand the key points here. Regarding the OP question any quality bearing is preferable SKF,***,NSK,NTN. Note that in terms of sealing efficiency the NTN full contact seals have a 2 lips on each side (NTN suffix LLU). These are by far the best options for keeping dirt out in my experience. You can halve the seal drag by removing the inboard seal if the BB housing bore has no access holes from the frame tubes.
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I posted this in the 'Who is Hambini' thread also:
AC bearings can last longer in BB30 applications because they have higher load ratings than radial ball bearings. This is down to the filling method of the radial balls (look up Conrad filling method). So an AC of the same size will have more balls and a higher load rating than a radial bearing. So basically nothing to do with axial loads and/or preload. AC has slight rigidity benefit too as the 'effective centres' of the bearing are further apart. Forces are applied to the bearing where a line drawn through the contact angle bisects the axle centreline. However AC is only effective with fixed mechanical adjustment (e.g.screw thread). If your BB is preloading the bearings with a wavy spring then it wont be an AC under a radial load.
Now if you take a radial bearing with a higher radial clearance (C3) and apply preload it becomes an AC albeit with a low contact angle (typically 10~12deg). A bearing with lower clearance or 'standard' clearance CN will have a lower contact angle when preloaded. So C3 clearance will give you a marginal theoretical benefit but misses the main advantage of an AC which is the higher load rating. However the extra clearance in a C3 can be helpful if the machining of your BB is not very accurate and the two bearing positions are misaligned relative to each other.
OK so now lets have a look at precision bearings. Actually the P classes are ISO (Euro & Asia) and ABEC are ANSI (USA) but they are directly comparable P0 (ABEC-1) is standard then P6,P5,P4 & P2 (ABEC-3,5.7 & 9) are all improvements. Now consider that a BB30 bearing size 6806; the standard clearance, standard precision version of which is rated to run at max 15,000rpm and will do so all day long if so required. Now consider that the main benefit of higher precision bearings comes when you wish to exceed the max speed rating of a 'standard' bearing. Then consider that very few cyclists can get anywhere near a 200rpm cadence (yes that is 1.3% of the available speed capability!) Also higher precision bearings demand higher precision from the mating axle and housing journals so fitting them to standard parts has no benefit at all.
No matter how fast you think you are ALL BEARINGS IN BICYCLES OPERATE AT LOW SPEED. That is also why ceramics offer absolutely no tangible benefits for cyclists.
More than 50% of the drag in an unloaded bearing will come from the seals. This will reduce to less than 50% under load because mechanical drag is proportional to load and seal drag is constant. Now the 50% figure will apply to full contact seals (for example NTN seals have two contact lips at each side - which is why they last so well). This can be reduced by using low friction seals (single contact lip), non-contact seals or metal shields. There is no getting away from the fact that seal drag and sealing efficiency are directly related. As soon as you get any dirt inside a bearing you will massively increase the drag torque. This is down to the tolerances and clearances; again using the BB30 size 6806 as an example a CN version will have a radial clearance of 5~20microns (1 micron = 0.001mm) the C3 version 13~28microns. Now consider that a human hair has an thickness somewhere between 50 and 250microns; probably best to keep your helmet and shorts on when servicing your bearings!
If you want to give your cartridge bearings the best start in life try running them in before you fit them. Because bicycle application speeds are so slow the correct grease distribution does not happen. Therefore fix up your electric drill to spin them for 10 minutes at a few thousand rpm. This will help distribute the grease which has many benefits; reduced drag in bearing and seal, improved sealing efficiency, better corrosion protection & better lubrication.
Apologies if this is a bit heavy going but hopefully some of you will understand the key points here. Regarding the OP question any quality bearing is preferable SKF,***,NSK,NTN. Note that in terms of sealing efficiency the NTN full contact seals have a 2 lips on each side (NTN suffix LLU). These are by far the best options for keeping dirt out in my experience. You can halve the seal drag by removing the inboard seal if the BB housing bore has no access holes from the frame tubes.
AC bearings can last longer in BB30 applications because they have higher load ratings than radial ball bearings. This is down to the filling method of the radial balls (look up Conrad filling method). So an AC of the same size will have more balls and a higher load rating than a radial bearing. So basically nothing to do with axial loads and/or preload. AC has slight rigidity benefit too as the 'effective centres' of the bearing are further apart. Forces are applied to the bearing where a line drawn through the contact angle bisects the axle centreline. However AC is only effective with fixed mechanical adjustment (e.g.screw thread). If your BB is preloading the bearings with a wavy spring then it wont be an AC under a radial load.
Now if you take a radial bearing with a higher radial clearance (C3) and apply preload it becomes an AC albeit with a low contact angle (typically 10~12deg). A bearing with lower clearance or 'standard' clearance CN will have a lower contact angle when preloaded. So C3 clearance will give you a marginal theoretical benefit but misses the main advantage of an AC which is the higher load rating. However the extra clearance in a C3 can be helpful if the machining of your BB is not very accurate and the two bearing positions are misaligned relative to each other.
OK so now lets have a look at precision bearings. Actually the P classes are ISO (Euro & Asia) and ABEC are ANSI (USA) but they are directly comparable P0 (ABEC-1) is standard then P6,P5,P4 & P2 (ABEC-3,5.7 & 9) are all improvements. Now consider that a BB30 bearing size 6806; the standard clearance, standard precision version of which is rated to run at max 15,000rpm and will do so all day long if so required. Now consider that the main benefit of higher precision bearings comes when you wish to exceed the max speed rating of a 'standard' bearing. Then consider that very few cyclists can get anywhere near a 200rpm cadence (yes that is 1.3% of the available speed capability!) Also higher precision bearings demand higher precision from the mating axle and housing journals so fitting them to standard parts has no benefit at all.
No matter how fast you think you are ALL BEARINGS IN BICYCLES OPERATE AT LOW SPEED. That is also why ceramics offer absolutely no tangible benefits for cyclists.
More than 50% of the drag in an unloaded bearing will come from the seals. This will reduce to less than 50% under load because mechanical drag is proportional to load and seal drag is constant. Now the 50% figure will apply to full contact seals (for example NTN seals have two contact lips at each side - which is why they last so well). This can be reduced by using low friction seals (single contact lip), non-contact seals or metal shields. There is no getting away from the fact that seal drag and sealing efficiency are directly related. As soon as you get any dirt inside a bearing you will massively increase the drag torque. This is down to the tolerances and clearances; again using the BB30 size 6806 as an example a CN version will have a radial clearance of 5~20microns (1 micron = 0.001mm) the C3 version 13~28microns. Now consider that a human hair has an thickness somewhere between 50 and 250microns; probably best to keep your helmet and shorts on when servicing your bearings!
If you want to give your cartridge bearings the best start in life try running them in before you fit them. Because bicycle application speeds are so slow the correct grease distribution does not happen. Therefore fix up your electric drill to spin them for 10 minutes at a few thousand rpm. This will help distribute the grease which has many benefits; reduced drag in bearing and seal, improved sealing efficiency, better corrosion protection & better lubrication.
Apologies if this is a bit heavy going but hopefully some of you will understand the key points here. Regarding the OP question any quality bearing is preferable SKF,***,NSK,NTN. Note that in terms of sealing efficiency the NTN full contact seals have a 2 lips on each side (NTN suffix LLU). These are by far the best options for keeping dirt out in my experience. You can halve the seal drag by removing the inboard seal if the BB housing bore has no access holes from the frame tubes.
#32
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Many thanks. The details of cup and cone AC design explain several subtle aspects of bearing optimization in bicycles and why substituted cartridge bearings frequently perform less well. (Connecting the dots for the reader: frequent repetition of marketing blather continuously violates subtle truths.)
Bottom brackets are a good example of this. When C&C were largely replaced by integrated assemblies that fitted inside the BB shell the bearing load ratings were too low (insufficient space). By moving to external BB cups they could fit larger bearings mounted further apart (a win-win) and the durability came back.
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Any low volume bottom bracket or hub manufacturer prefers to use sealed cartridge bearings. They can't afford / don't have the knowledge to develop separate cup and cone components. The cartridge bearing offers them an easy off-the-shelf solution; readily available and with integral seals and grease. In most cases where cartridge bearings perform less well than C&C they will have spec'd bearings which are too small (load rating too low), or they corrode through water ingress as the bearing seals are not properly protected.
Bottom brackets are a good example of this. When C&C were largely replaced by integrated assemblies that fitted inside the BB shell the bearing load ratings were too low (insufficient space). By moving to external BB cups they could fit larger bearings mounted further apart (a win-win) and the durability came back.
Bottom brackets are a good example of this. When C&C were largely replaced by integrated assemblies that fitted inside the BB shell the bearing load ratings were too low (insufficient space). By moving to external BB cups they could fit larger bearings mounted further apart (a win-win) and the durability came back.
Some of Shimano's early non-gruppo cartridge BBs were actually enclosed cup & cone with a threaded cone and locknut (LP20, 21, etc). No surprise that they were some of the most durable.
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BB30 specific brgs have a larger radius on the outer race which facilitates installation. The smaller radius (std) on the commercial brg could damage the brg cavity on yr frame if you are not very careful when installing the brgs. When I noticed this difference I returned the commercial ones, and bought the BB30 specific ones.
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BB30 specific brgs have a larger radius on the outer race which facilitates installation. The smaller radius (std) on the commercial brg could damage the brg cavity on yr frame if you are not very careful when installing the brgs. When I noticed this difference I returned the commercial ones, and bought the BB30 specific ones.
Last edited by brooklyn6640; 11-01-19 at 05:14 PM.
#37
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Imo the is no need for botique stuff. Industry grade bearings are already as good as it gets. Only issue is they might not fit what ever bike you have. Lots of proprietary stuff out there that require proprietary or non standard replacement parts.
Last edited by Racing Dan; 11-02-19 at 06:26 AM.
#38
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Sorry to be a grouch, but you (and others with similar concerns about bearing friction or bike component weight) have lost far more in the time you have already spent obsessing over an inconsequential factor, let alone the time ordering and installing, than you will gain. If you want more efficiency/speed the time would have been better spent on the road.
#39
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Sorry to be a grouch, but you (and others with similar concerns about bearing friction or bike component weight) have lost far more in the time you have already spent obsessing over an inconsequential factor, let alone the time ordering and installing, than you will gain. If you want more efficiency/speed the time would have been better spent on the road.
#40
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The original topic had nothng to do with getting repairs right, so my comment stands. I was not criticizing the info that arose incidentally that could actually be of some use.
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Sorry to be a grouch, but you (and others with similar concerns about bearing friction or bike component weight) have lost far more in the time you have already spent obsessing over an inconsequential factor, let alone the time ordering and installing, than you will gain. If you want more efficiency/speed the time would have been better spent on the road.
#42
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No, you also misread my post. I am saying that if your goal is to be more efficient or fast, then it's better to ride your bike than to spend time on "engineering for speed" IF your focus is on something that will not accomplish that nearly as efficiently as riding. Within normal adjustment and condition parameters I would think that improved bearings in a BB would accomplish far less than one-tenth of a percent improvement. A change in weight of .5 lbs for a combined 180lb rider and bike is less than three-tenths of a percent improvement, and only on inertial efficiency, which is negligible at higher speeds. Less weight does help on an uphill, but is partially offset downhill.
If you enjoy the engineering aspect primarily for the fun of it that's a different matter, but that was not what the OP indicated.
If you enjoy the engineering aspect primarily for the fun of it that's a different matter, but that was not what the OP indicated.