Press Fit Bottom Bracket
02-28-22, 02:03 PM
#76
Senior Member
Not to mention, threaded BBs doesn't solve the issue with creaking if it originate in the interface between the axle and the bearing, as it sometimes does in BBs that doesnt have a sleeve, like Shimano has. My Praxis GXP exhibit that annoying behaviour.
02-28-22, 02:16 PM
#77
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None of those things are arguments for external bearings. In fact pretty much all of them should be better with pressfit bearings that are inside the bottom bracket. For me the main point of the video is that the problem with pressfit is poor manufacturing tolerances. Bike brands are going back to threaded not because it is the better solution but because it's easier than fixing the manufacturing problems. Given what carbon frames cost it seems reasonable to expect the better manufacturing especially given there are probably other misalignments that don't creak so go unnoticed.
Ultimately, if threaded bottom brackets is important to someone when buying a bike more power to them.
Ultimately, if threaded bottom brackets is important to someone when buying a bike more power to them.
PFBB is nothing more than solution looking for a problem.
02-28-22, 02:53 PM
#78
Full Member
That's not entirely accurate. Pressfit was switched to and is still used for actual benefits. As you say it is lighter. It is also easier to make it stiff with oversized bottom bracket areas. It's also narrower which means there is less leverage applied and it is easier to make room for wider tires. Also the bearings are less exposed to the elements. Bottom brackets aren't usually installed on the assembly line, so I don't think that matters. It's probably a little easier not having to put in the threads, but the initial switch to pressfit was because of performance gains not because it was cheaper to manufacture. Certainly, you can argue that the gains weren't worth the troubles introduced, but the reason for going to pressfit was because it was believed to be a better system.
03-03-22, 03:45 PM
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Bike brands are going back to threaded because it's cheaper than paying for pre-mature warranty claims on a system that is poorly designed for the loads and environments it's subjected to. The only reason manufactures switched to PFBB is because A.) makes the bike lighter and B.) quicker to manufacture going down the assembly line as it's easier and faster to press in bearings than to have to thread a cup in.
PFBB is nothing more than solution looking for a problem.
PFBB is nothing more than solution looking for a problem.
03-03-22, 04:34 PM
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If I'm the original owner, I prefer threaded. If I am buying used, PF would be my preference. Not having threads lessens the chances of the BB area being all doo doo.
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03-04-22, 05:08 PM
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03-07-22, 11:54 AM
#83
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Seems to me like a properly made PF has (marginal) weight and width advantages over threaded, but bike manufacturers have been poor at delivering this solution in a reliably well made form.
Inconsistency in the manufacturing of PF makes a retreat to the previous reliable and better understood method seem like a safe move.
This is more of a gambling question than a performance one. If you were guaranteed to have a non-creaking PFBB that was lighter and more aero than threaded you'd probably take it, but since that guarantee doesn't exist...
Inconsistency in the manufacturing of PF makes a retreat to the previous reliable and better understood method seem like a safe move.
This is more of a gambling question than a performance one. If you were guaranteed to have a non-creaking PFBB that was lighter and more aero than threaded you'd probably take it, but since that guarantee doesn't exist...
Last edited by Overdraft; 03-08-22 at 05:50 PM. Reason: always fixin' typos
03-07-22, 12:34 PM
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I'd argue the opposite. Pressing bearings into machined alloy cartridges, and bonding threaded inserts into a bike frame seems more complicated to me than pressing/bonding a metal sleeve into the BB shell and inserting bearings directly. That's pretty much what you get if you have BB386 or BB86 and use a hambini BB.
03-08-22, 01:16 PM
#85
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Oh my...
What a way to get my gears grinding.
A few disclaimers: 1.Hambini is a hack and a non-starter. 2.I took the time to watch the Bike Radar guy while making a cup of coffee and spent half the time yelling at him about all that he was wrong about. 3. I lived through and was a mechanic during all of these BB transitions.
Pressfit is a fabulous idea but just horribly executed in the bike industry for a myriad of reasons. Every single engineer with good intentions has tried. They have all failed. The only good pressfit solutions that I have seen operate reliably are the ones that are simply thread together BB's that are installed in a pressfit shell.
The alignment bit - OMFG are you kidding me? Have none of you ever done an ounce of machining?? A molded carbon bearing pocket is harder to align than a machined and threaded feature. In fact composite materials and manufacturing processes make horrible bearing pockets. That combined with the inability to reliably manufacture tight tolerance bearing pockets that don't change shape under load over time make it a really poor application. I did like one comment on the Bike Radar video. The guy in the video likes to say the problem is simply that we can't produce with good tolerances as if to imply everyone in manufacturing just doesn't know what they're doing. The comment took aim at that by saying, "flying cars are by far the best application of cars but they can't seem to be reliably manufactured".
Also on alignment - I have these amazing tools that I use to chase threads, using tight tolerance guides to assure alignment and then another set of guides to allow me to machine the BB face to be perpendicular all while at room temp and on the bike. The closest equivalent on the PF side uses a fixturing cone.
BTW - I do clean up and face all PF bores as well. You'd be amazed at how many are done so very badly.
Durability/longevity. etc. - For the same level of components (quality and type of bearings and seals) threaded BB's outlast the PF equivalent.
Even the carbon experts like Rukus that I have listened to talk about this issue admit you have to use locking compounds like loctite in order to get reasonable performance out of a PF BB. This completely ignores the fact that that bikes last and need service including replacing BB's at some point. Unthreading a BB and replacing it while in the field at an event means I can get the rider back into the mix. Banging and pressing a loctite BB out and cleaning up the pocket and re-prepping and bonding a new one in the field ...
*The OVERWHELMING majority of creaking and noise complaints people have that they boil down to BB and crank issues (most shops even jump to that) are NOT in fact BB or crank issues. One of my favorites was a lady who kept having creaking issues. Took it to a shop that I know and love with good mechanics. They replaced the BB. It came back. They replaced it again. It came back. They replaced the BB and crank. It came back. Then they recabled the bike and replaced everything they could while doing a complete overhaul. It came back. They then told her the bike was crap. It was a Van Dessel that I had originally sold and she bought used. Before chucking it she came out to me to have me look at it ( a bit of a drive from the city). Though basic, systematic troubleshooting I was able to determine the noise was coming from the seat post that, at her ride height, was bottoming out against the riv-nuts for the bottle cage. I cut a couple mm off the end of her seatpost and the bike has been silent since. I've seen all sorts of BB creaks end up being: headsets, seatpost binders, seatpost clamps, saddles, dropouts/hangers, QR skewers, TA Bolts, pedals, and hub driveshells. It is very seldom the actual BB.
To say a PF BB is better because it eliminates the middle bits of material that "aren't needed" is a bit like saying you can tie a worm up with fishing line and catch fish. The important parts of the process are the bait to attract the fish and the line to reel it in. The hook is a poor substitute for not being able to get the fish on to the line efficiently.
What a way to get my gears grinding.
A few disclaimers: 1.Hambini is a hack and a non-starter. 2.I took the time to watch the Bike Radar guy while making a cup of coffee and spent half the time yelling at him about all that he was wrong about. 3. I lived through and was a mechanic during all of these BB transitions.
Pressfit is a fabulous idea but just horribly executed in the bike industry for a myriad of reasons. Every single engineer with good intentions has tried. They have all failed. The only good pressfit solutions that I have seen operate reliably are the ones that are simply thread together BB's that are installed in a pressfit shell.
The alignment bit - OMFG are you kidding me? Have none of you ever done an ounce of machining?? A molded carbon bearing pocket is harder to align than a machined and threaded feature. In fact composite materials and manufacturing processes make horrible bearing pockets. That combined with the inability to reliably manufacture tight tolerance bearing pockets that don't change shape under load over time make it a really poor application. I did like one comment on the Bike Radar video. The guy in the video likes to say the problem is simply that we can't produce with good tolerances as if to imply everyone in manufacturing just doesn't know what they're doing. The comment took aim at that by saying, "flying cars are by far the best application of cars but they can't seem to be reliably manufactured".
Also on alignment - I have these amazing tools that I use to chase threads, using tight tolerance guides to assure alignment and then another set of guides to allow me to machine the BB face to be perpendicular all while at room temp and on the bike. The closest equivalent on the PF side uses a fixturing cone.
BTW - I do clean up and face all PF bores as well. You'd be amazed at how many are done so very badly.
Durability/longevity. etc. - For the same level of components (quality and type of bearings and seals) threaded BB's outlast the PF equivalent.
Even the carbon experts like Rukus that I have listened to talk about this issue admit you have to use locking compounds like loctite in order to get reasonable performance out of a PF BB. This completely ignores the fact that that bikes last and need service including replacing BB's at some point. Unthreading a BB and replacing it while in the field at an event means I can get the rider back into the mix. Banging and pressing a loctite BB out and cleaning up the pocket and re-prepping and bonding a new one in the field ...
*The OVERWHELMING majority of creaking and noise complaints people have that they boil down to BB and crank issues (most shops even jump to that) are NOT in fact BB or crank issues. One of my favorites was a lady who kept having creaking issues. Took it to a shop that I know and love with good mechanics. They replaced the BB. It came back. They replaced it again. It came back. They replaced the BB and crank. It came back. Then they recabled the bike and replaced everything they could while doing a complete overhaul. It came back. They then told her the bike was crap. It was a Van Dessel that I had originally sold and she bought used. Before chucking it she came out to me to have me look at it ( a bit of a drive from the city). Though basic, systematic troubleshooting I was able to determine the noise was coming from the seat post that, at her ride height, was bottoming out against the riv-nuts for the bottle cage. I cut a couple mm off the end of her seatpost and the bike has been silent since. I've seen all sorts of BB creaks end up being: headsets, seatpost binders, seatpost clamps, saddles, dropouts/hangers, QR skewers, TA Bolts, pedals, and hub driveshells. It is very seldom the actual BB.
To say a PF BB is better because it eliminates the middle bits of material that "aren't needed" is a bit like saying you can tie a worm up with fishing line and catch fish. The important parts of the process are the bait to attract the fish and the line to reel it in. The hook is a poor substitute for not being able to get the fish on to the line efficiently.
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03-09-22, 08:00 AM
#86
Junior Member
Oh my...
What a way to get my gears grinding.
A few disclaimers: 1.Hambini is a hack and a non-starter. 2.I took the time to watch the Bike Radar guy while making a cup of coffee and spent half the time yelling at him about all that he was wrong about. 3. I lived through and was a mechanic during all of these BB transitions.
Pressfit is a fabulous idea but just horribly executed in the bike industry for a myriad of reasons. Every single engineer with good intentions has tried. They have all failed. The only good pressfit solutions that I have seen operate reliably are the ones that are simply thread together BB's that are installed in a pressfit shell.
The alignment bit - OMFG are you kidding me? Have none of you ever done an ounce of machining?? A molded carbon bearing pocket is harder to align than a machined and threaded feature. In fact composite materials and manufacturing processes make horrible bearing pockets. That combined with the inability to reliably manufacture tight tolerance bearing pockets that don't change shape under load over time make it a really poor application. I did like one comment on the Bike Radar video. The guy in the video likes to say the problem is simply that we can't produce with good tolerances as if to imply everyone in manufacturing just doesn't know what they're doing. The comment took aim at that by saying, "flying cars are by far the best application of cars but they can't seem to be reliably manufactured".
Also on alignment - I have these amazing tools that I use to chase threads, using tight tolerance guides to assure alignment and then another set of guides to allow me to machine the BB face to be perpendicular all while at room temp and on the bike. The closest equivalent on the PF side uses a fixturing cone.
BTW - I do clean up and face all PF bores as well. You'd be amazed at how many are done so very badly.
Durability/longevity. etc. - For the same level of components (quality and type of bearings and seals) threaded BB's outlast the PF equivalent.
Even the carbon experts like Rukus that I have listened to talk about this issue admit you have to use locking compounds like loctite in order to get reasonable performance out of a PF BB. This completely ignores the fact that that bikes last and need service including replacing BB's at some point. Unthreading a BB and replacing it while in the field at an event means I can get the rider back into the mix. Banging and pressing a loctite BB out and cleaning up the pocket and re-prepping and bonding a new one in the field ...
*The OVERWHELMING majority of creaking and noise complaints people have that they boil down to BB and crank issues (most shops even jump to that) are NOT in fact BB or crank issues. One of my favorites was a lady who kept having creaking issues. Took it to a shop that I know and love with good mechanics. They replaced the BB. It came back. They replaced it again. It came back. They replaced the BB and crank. It came back. Then they recabled the bike and replaced everything they could while doing a complete overhaul. It came back. They then told her the bike was crap. It was a Van Dessel that I had originally sold and she bought used. Before chucking it she came out to me to have me look at it ( a bit of a drive from the city). Though basic, systematic troubleshooting I was able to determine the noise was coming from the seat post that, at her ride height, was bottoming out against the riv-nuts for the bottle cage. I cut a couple mm off the end of her seatpost and the bike has been silent since. I've seen all sorts of BB creaks end up being: headsets, seatpost binders, seatpost clamps, saddles, dropouts/hangers, QR skewers, TA Bolts, pedals, and hub driveshells. It is very seldom the actual BB.
To say a PF BB is better because it eliminates the middle bits of material that "aren't needed" is a bit like saying you can tie a worm up with fishing line and catch fish. The important parts of the process are the bait to attract the fish and the line to reel it in. The hook is a poor substitute for not being able to get the fish on to the line efficiently.
What a way to get my gears grinding.
A few disclaimers: 1.Hambini is a hack and a non-starter. 2.I took the time to watch the Bike Radar guy while making a cup of coffee and spent half the time yelling at him about all that he was wrong about. 3. I lived through and was a mechanic during all of these BB transitions.
Pressfit is a fabulous idea but just horribly executed in the bike industry for a myriad of reasons. Every single engineer with good intentions has tried. They have all failed. The only good pressfit solutions that I have seen operate reliably are the ones that are simply thread together BB's that are installed in a pressfit shell.
The alignment bit - OMFG are you kidding me? Have none of you ever done an ounce of machining?? A molded carbon bearing pocket is harder to align than a machined and threaded feature. In fact composite materials and manufacturing processes make horrible bearing pockets. That combined with the inability to reliably manufacture tight tolerance bearing pockets that don't change shape under load over time make it a really poor application. I did like one comment on the Bike Radar video. The guy in the video likes to say the problem is simply that we can't produce with good tolerances as if to imply everyone in manufacturing just doesn't know what they're doing. The comment took aim at that by saying, "flying cars are by far the best application of cars but they can't seem to be reliably manufactured".
Also on alignment - I have these amazing tools that I use to chase threads, using tight tolerance guides to assure alignment and then another set of guides to allow me to machine the BB face to be perpendicular all while at room temp and on the bike. The closest equivalent on the PF side uses a fixturing cone.
BTW - I do clean up and face all PF bores as well. You'd be amazed at how many are done so very badly.
Durability/longevity. etc. - For the same level of components (quality and type of bearings and seals) threaded BB's outlast the PF equivalent.
Even the carbon experts like Rukus that I have listened to talk about this issue admit you have to use locking compounds like loctite in order to get reasonable performance out of a PF BB. This completely ignores the fact that that bikes last and need service including replacing BB's at some point. Unthreading a BB and replacing it while in the field at an event means I can get the rider back into the mix. Banging and pressing a loctite BB out and cleaning up the pocket and re-prepping and bonding a new one in the field ...
*The OVERWHELMING majority of creaking and noise complaints people have that they boil down to BB and crank issues (most shops even jump to that) are NOT in fact BB or crank issues. One of my favorites was a lady who kept having creaking issues. Took it to a shop that I know and love with good mechanics. They replaced the BB. It came back. They replaced it again. It came back. They replaced the BB and crank. It came back. Then they recabled the bike and replaced everything they could while doing a complete overhaul. It came back. They then told her the bike was crap. It was a Van Dessel that I had originally sold and she bought used. Before chucking it she came out to me to have me look at it ( a bit of a drive from the city). Though basic, systematic troubleshooting I was able to determine the noise was coming from the seat post that, at her ride height, was bottoming out against the riv-nuts for the bottle cage. I cut a couple mm off the end of her seatpost and the bike has been silent since. I've seen all sorts of BB creaks end up being: headsets, seatpost binders, seatpost clamps, saddles, dropouts/hangers, QR skewers, TA Bolts, pedals, and hub driveshells. It is very seldom the actual BB.
To say a PF BB is better because it eliminates the middle bits of material that "aren't needed" is a bit like saying you can tie a worm up with fishing line and catch fish. The important parts of the process are the bait to attract the fish and the line to reel it in. The hook is a poor substitute for not being able to get the fish on to the line efficiently.
ther things he did besides the BB service. Bike is a Bianchi Infinito with a PF BB.
