Is BB30 fixed?
04-10-14, 01:35 AM
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So BB30 turns out to be a bit dubious in practice because of the tolerances, bummer. But PF30 appears to solve the issues.
Now, if we can get someone to make a BB for PF30/24mm that uses the extra room to give us the durability of square-taper bearings, it'll be win/win/win.
04-10-14, 05:16 AM
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Any opportunity to get rid of large-diameter threads should be thoroughly pursued, IMO. They're a PITA and better consigned to history.
So BB30 turns out to be a bit dubious in practice because of the tolerances, bummer. But PF30 appears to solve the issues.
Now, if we can get someone to make a BB for PF30/24mm that uses the extra room to give us the durability of square-taper bearings, it'll be win/win/win.
So BB30 turns out to be a bit dubious in practice because of the tolerances, bummer. But PF30 appears to solve the issues.
Now, if we can get someone to make a BB for PF30/24mm that uses the extra room to give us the durability of square-taper bearings, it'll be win/win/win.
Answer? BB30 can be a problem for the majority that don't know how to set it up...which is probably the majority of those that own it. For a skilled wrench, BB30 is excellent. So there is a parallel universe out there and why the divide on the subject.
As to PF30 being less problematic than BB30. Nope, wrong again. Neither are problematic with proper set up.
Lastly, BB30 being more or less sensitive to tolerance variation? Nope, wrong again. Even after 100 bearing replacements, using Loctite to glue bearings into BB30 bores will compensate for even 'clearance' and not press or slip fit between bores.
In summary the reason that both BB30 and PF30 are hanging around after many years and haven't been replaced is because for those that know how to install them properly...and service them periodically as needed, there is no issue. BB30 and PF30 represent the lightest and stiffess BB in history with larger bearings which in practice if properly maintained should represent less bearing drag and better durability.
All that don't have the above experience...you fail the litmus test....it isn't the design, its you.
Last edited by Campag4life; 04-10-14 at 06:32 AM.
04-10-14, 05:44 AM
#28
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I understand the "gibberish" part- no offense taken. I'm not an ME either, therefore might have a problem being understood. It's a bit difficult to explain in text , and maybe even harder to understand. Let's try a different approach.
If you follow "instructions" and seat both bearings into the shell... all is well until you push the spindle into the bearings. Since the spindle is an interference fit in the inner race, the bearings will be sideloaded (for lack of a better term) whether you push, or pull the spindle through.
If you support the inner race with your puller it pulls into the inner race only. If you follow "directions" you push, or pull the spindle in, but the bearing is only supported on the outer race in the shell. All the stress is on the balls. Once in place following "directions" there's no good way for correction to center the bearing. Same way for installation of the NDS. If you followed "directions" the NDS bearing would already be in place. Driving the spindle in would stress bearings on both sides.
I push the NDS bearing in after the crank spindle is set in the DS. Here's a part that may be tough to understand (as per your question.) I support both races because there's an interference fit on both the inner and outer races. To use one race or the other to seat the bearing would side- load the balls. As mentioned, the puller is supported on the outside of the DS spindle. Not doing so would sideload the DS bearing so one could pull in the other side. Doing do allows the DS bearing to float free, rather than using the shell to support the puller. Still clear as mud?
Problem is, well not really, you have to fashion your own puller set. If you do enough BB30/PF30 work, and you want them to run free, it's no biggee- about an hours worth of lathe time.
If you follow "instructions" and seat both bearings into the shell... all is well until you push the spindle into the bearings. Since the spindle is an interference fit in the inner race, the bearings will be sideloaded (for lack of a better term) whether you push, or pull the spindle through.
If you support the inner race with your puller it pulls into the inner race only. If you follow "directions" you push, or pull the spindle in, but the bearing is only supported on the outer race in the shell. All the stress is on the balls. Once in place following "directions" there's no good way for correction to center the bearing. Same way for installation of the NDS. If you followed "directions" the NDS bearing would already be in place. Driving the spindle in would stress bearings on both sides.
I push the NDS bearing in after the crank spindle is set in the DS. Here's a part that may be tough to understand (as per your question.) I support both races because there's an interference fit on both the inner and outer races. To use one race or the other to seat the bearing would side- load the balls. As mentioned, the puller is supported on the outside of the DS spindle. Not doing so would sideload the DS bearing so one could pull in the other side. Doing do allows the DS bearing to float free, rather than using the shell to support the puller. Still clear as mud?
Problem is, well not really, you have to fashion your own puller set. If you do enough BB30/PF30 work, and you want them to run free, it's no biggee- about an hours worth of lathe time.
First there is no interference fit between spindle and ID of inner race...it is a slip fit with angular tolerance. Btw, I am a ME.
BB30 bore to bore cylindricity for all top frame makers in the industry accounts for outer to inner race bearing tolerance that allows for a tolerance of lack of co-axiality. So precise alignment or sharing the same axial centerline of both bearings isn't essential. Of course it needs to be close and most top frames are.
A little know fact among I would say most that think they know bicycles is....an English threaded BB will have greater axial bearing mismatch bearing to bearing centerline compared to BB30. This for example is one of the benefits of BB30, better agreement of bearing position side to side for lowest possible rotational friction.
As far as pressing in bearings goes...always press them in with pressure on the outer race. This is the ONLY way to do it to ensure the bearings aren't spoiled. Trying to press on both inner and outer races concurrently will create more harm than good. because any side load on the inner race with restraint to the outer race can damage the balls or races.
The biggest mistakes that techs make when installing BB30 are:
1. BB30 bores and bearing outer races aren't perfectly clean.
2. Loctite isn't used or wrong spec Loctite is used.
3. Bearings aren't pressed in absolutely straight aka orthogonal to bores which ensure proper bearing centerline agreement and seated fully to mating snap rings.
4. Crank preload is set wrong...either too loose aka play or too tight which will increase spindle drag and induce premature bearing wear. For wave washer cranks which account for a large percentage, the wave washer should be compressed to approx. 1/2 of its free standing height. This take careful selection of spacers based upon BB shell size/tolerance.
You don't have to or more importantly, you shouldn't use the spindle as a mandrel to promote alignment between bores as you propose.
Last edited by Campag4life; 04-10-14 at 05:57 AM.
04-10-14, 05:57 AM
#29
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Nope...what you write, just isn't so. Oh you can do it your way which you probably have but there is no value added and in fact maybe worse. Pressing both bearings in place first and then installing the crank spindle is industry practice and a sound approach.
First there is no interference fit between spindle and ID of inner race...it is a slip fit with angular tolerance. Btw, I am a ME.
BB30 bore to bore cylindricity for all top frame makers in the industry accounts for outer to inner race bearing tolerance that allows for a tolerance of lack of co-axiality. So precise alignment or sharing the same axial centerline of both bearings isn't essential. Of course it needs to be close and most top frames are.
A little know fact among I would say most that think they know bicycles is....an English threaded BB will have greater axial bearing mismatch bearing to bearing centerline compared to BB30. This for example is one of the benefits of BB30, better agreement of bearing position side to side for lowest possible rotational friction.
As far as pressing in bearings goes...always press them in with pressure on the outer race. This is the ONLY way to do it to ensure the bearings aren't spoiled. Trying to press on both inner and outer races concurrently will create more harm than good. because any side load on the inner race with restraint to the outer race can damage the balls or races.
The biggest mistakes that techs make when installing BB30 are:
1. BB30 bores and bearing outer races aren't perfectly clean.
2. Loctite isn't used or wrong spec Loctite is used.
3. Bearings aren't pressed in absolutely straight aka orthogonal to bores which ensure proper bearing centerline agreement and seated fully to mating snap rings.
4. Crank preload is set wrong...either too loose aka play or too tight which will increase spindle drag and induce premature wear. For wave washer cranks which account for a large percentage, the wave washer should be compressed to approx. 1/2 of its free standing height. This take careful selection of spacers based upon BB shell size/tolerance.
You don't have to or more importantly, you shouldn't use the spindle as a mandrel to promote alignment between bores as you propose.
First there is no interference fit between spindle and ID of inner race...it is a slip fit with angular tolerance. Btw, I am a ME.
BB30 bore to bore cylindricity for all top frame makers in the industry accounts for outer to inner race bearing tolerance that allows for a tolerance of lack of co-axiality. So precise alignment or sharing the same axial centerline of both bearings isn't essential. Of course it needs to be close and most top frames are.
A little know fact among I would say most that think they know bicycles is....an English threaded BB will have greater axial bearing mismatch bearing to bearing centerline compared to BB30. This for example is one of the benefits of BB30, better agreement of bearing position side to side for lowest possible rotational friction.
As far as pressing in bearings goes...always press them in with pressure on the outer race. This is the ONLY way to do it to ensure the bearings aren't spoiled. Trying to press on both inner and outer races concurrently will create more harm than good. because any side load on the inner race with restraint to the outer race can damage the balls or races.
The biggest mistakes that techs make when installing BB30 are:
1. BB30 bores and bearing outer races aren't perfectly clean.
2. Loctite isn't used or wrong spec Loctite is used.
3. Bearings aren't pressed in absolutely straight aka orthogonal to bores which ensure proper bearing centerline agreement and seated fully to mating snap rings.
4. Crank preload is set wrong...either too loose aka play or too tight which will increase spindle drag and induce premature wear. For wave washer cranks which account for a large percentage, the wave washer should be compressed to approx. 1/2 of its free standing height. This take careful selection of spacers based upon BB shell size/tolerance.
You don't have to or more importantly, you shouldn't use the spindle as a mandrel to promote alignment between bores as you propose.
04-10-14, 09:19 AM
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Red Dog: any plans on coming to North Carolina in the next few days by any chance? Asheville's good riding country, though the cannondale dealership here seems unable to fix my creaking bb30.... Its months into it now. And still creak, creak, creak with every ride....
"Is BB30 fixed?" This IMO, so take it for what's it's worth. First, there was nothing to fix as a design and standard goes, but the close tolerances required for long life are not able to be met in this industry.
BB30 really has no advantage a as a bottom bracket type other than light weight (on the user level) and simplification at the mfr. level. The mfr. can save on assembly time, and benefit from fewer parts.
BTW- the lighter weight part is a result of the aluminum spindle, which must be larger (30 vs. 24mm) to maintain strength and stiffness. Then there's the BB itself, which can save a few grams, but not enough to matter except to the weight wienies (which includes me.) That being said... I think it's a great system, but it has it's drawbacks in the bike industry.
Cannondale set the standard, but they seem to be one of the worst in following (their own) recommendations and tolerances and seem to have the most problems.
Consider that the spindle is larger and therefor requires a bearing with a larger id, and to fit the bearing od within the shell the balls are smaller and the material thickness of the race is thin. Therein lies part of the problem. The fit tolerance must be exact. On production frames it's normally too "tight" and there's no clearance for the lube, and it runs dry. So... the life is short. A dry bearing squeaks. FWIW- interference fit tolerance between the spindle and inner race, and the shell and out race should be no more than .0005".
No bike shop can measure to that degree of accuracy, nor do they have the means to machine to that tolerance, or to the degree or "roundness" required. No Park tool will get you there.
Another issue is "bearing distance." Maybe best described as the distance between the bearing seats in the shell. If these ain't spot on side loading of the bearing can occur. Again, nost bike shops are not equipped to deal with this, let alone measure. Then there's the install procedure.
Even Park tools site has it wrong. The install procedure has to insure that no side-loading of the bearing is present. If the tolerances are
"perfect" you can get by with "common" procedures. OTH, if the "slip-fit" is not right... setting the bearing into the frame and driving the spindle through, will side load the bearings every time.
I set the DS bearing first, and pull the crank in supporting the inner race. Then push the ND bearing in (supporting both inner and out races) pulling in from the outside of the DS spindle. This eliminates any side loads.
They can be made to work, and work well, and live forever- at least as long as any other bb bearing system.
Creaks? Who knows. Could be a tolerance issue, or a bearing issue. I will say (as someone eluded to) "adaptors have a tendency to creak." Of course. There's more parts involved so clearances must be right for the extra parts as well. My question is- if you have a BB30 frame, why adapt a different crank?
PF30 guys don't seem to have the same issues. PF30 and BB30 are the same crank. PF30 uses a "plastic" adapter" in the frame. This seems to more tolerant of "lousy" tolerances.
That's my take. I've had good success with curing BB30 problems for the racer types. Relatively easy compared to prepping race motors where there's five bearing saddles that must align and be clearanced to live at 10,000rpm, whereas a bike crank might spin at 120?
BB30 really has no advantage a as a bottom bracket type other than light weight (on the user level) and simplification at the mfr. level. The mfr. can save on assembly time, and benefit from fewer parts.
BTW- the lighter weight part is a result of the aluminum spindle, which must be larger (30 vs. 24mm) to maintain strength and stiffness. Then there's the BB itself, which can save a few grams, but not enough to matter except to the weight wienies (which includes me.) That being said... I think it's a great system, but it has it's drawbacks in the bike industry.
Cannondale set the standard, but they seem to be one of the worst in following (their own) recommendations and tolerances and seem to have the most problems.
Consider that the spindle is larger and therefor requires a bearing with a larger id, and to fit the bearing od within the shell the balls are smaller and the material thickness of the race is thin. Therein lies part of the problem. The fit tolerance must be exact. On production frames it's normally too "tight" and there's no clearance for the lube, and it runs dry. So... the life is short. A dry bearing squeaks. FWIW- interference fit tolerance between the spindle and inner race, and the shell and out race should be no more than .0005".
No bike shop can measure to that degree of accuracy, nor do they have the means to machine to that tolerance, or to the degree or "roundness" required. No Park tool will get you there.
Another issue is "bearing distance." Maybe best described as the distance between the bearing seats in the shell. If these ain't spot on side loading of the bearing can occur. Again, nost bike shops are not equipped to deal with this, let alone measure. Then there's the install procedure.
Even Park tools site has it wrong. The install procedure has to insure that no side-loading of the bearing is present. If the tolerances are
"perfect" you can get by with "common" procedures. OTH, if the "slip-fit" is not right... setting the bearing into the frame and driving the spindle through, will side load the bearings every time.
I set the DS bearing first, and pull the crank in supporting the inner race. Then push the ND bearing in (supporting both inner and out races) pulling in from the outside of the DS spindle. This eliminates any side loads.
They can be made to work, and work well, and live forever- at least as long as any other bb bearing system.
Creaks? Who knows. Could be a tolerance issue, or a bearing issue. I will say (as someone eluded to) "adaptors have a tendency to creak." Of course. There's more parts involved so clearances must be right for the extra parts as well. My question is- if you have a BB30 frame, why adapt a different crank?
PF30 guys don't seem to have the same issues. PF30 and BB30 are the same crank. PF30 uses a "plastic" adapter" in the frame. This seems to more tolerant of "lousy" tolerances.
That's my take. I've had good success with curing BB30 problems for the racer types. Relatively easy compared to prepping race motors where there's five bearing saddles that must align and be clearanced to live at 10,000rpm, whereas a bike crank might spin at 120?
04-10-14, 09:30 AM
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The only way to fix BB30 is to throw away your frame and buy one with a standard English threaded BB. Any design that takes a simple threaded interface and replaces it with a press fit is a step in the wrong direction IMO. Creaking and requiring Loctite are the results.
I am just so irritated that these corporate hacks have put out a product that offers no real benefit and makes life impossible for the non-mechanically inclined cyclist who purchased a new Cannondale bike. Crap product, defective product -- no customer support, just the old runaround. Oh man I'm pissed off.
04-10-14, 11:04 AM
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I wholeheartedly agree with the above. Alas I am not made of money. Also even if Cannondale agrees to replace the frame, well they only make caad with bb30 now.... and a reimbursement would get me nowhere as I got last years model a caad10 2012 for $1000 or so from REI.
I am just so irritated that these corporate hacks have put out a product that offers no real benefit and makes life impossible for the non-mechanically inclined cyclist who purchased a new Cannondale bike. Crap product, defective product -- no customer support, just the old runaround. Oh man I'm pissed off.
I am just so irritated that these corporate hacks have put out a product that offers no real benefit and makes life impossible for the non-mechanically inclined cyclist who purchased a new Cannondale bike. Crap product, defective product -- no customer support, just the old runaround. Oh man I'm pissed off.
04-10-14, 11:16 AM
#33
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I wholeheartedly agree with the above. Alas I am not made of money. Also even if Cannondale agrees to replace the frame, well they only make caad with bb30 now.... and a reimbursement would get me nowhere as I got last years model a caad10 2012 for $1000 or so from REI.
I am just so irritated that these corporate hacks have put out a product that offers no real benefit and makes life impossible for the non-mechanically inclined cyclist who purchased a new Cannondale bike. Crap product, defective product -- no customer support, just the old runaround. Oh man I'm pissed off.
I am just so irritated that these corporate hacks have put out a product that offers no real benefit and makes life impossible for the non-mechanically inclined cyclist who purchased a new Cannondale bike. Crap product, defective product -- no customer support, just the old runaround. Oh man I'm pissed off.
04-10-14, 04:14 PM
#34
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Any opportunity to get rid of large-diameter threads should be thoroughly pursued, IMO. They're a PITA and better consigned to history.
So BB30 turns out to be a bit dubious in practice because of the tolerances, bummer. But PF30 appears to solve the issues.
Now, if we can get someone to make a BB for PF30/24mm that uses the extra room to give us the durability of square-taper bearings, it'll be win/win/win.
So BB30 turns out to be a bit dubious in practice because of the tolerances, bummer. But PF30 appears to solve the issues.
Now, if we can get someone to make a BB for PF30/24mm that uses the extra room to give us the durability of square-taper bearings, it'll be win/win/win.
But if I got a frame with a press fit bottom bracket now I have to get a big, heavy, expensive bearing press. How is this better? Never mind that they offer no benefits.
04-10-14, 05:50 PM
#35
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Well, aside from having to pay for the framebuilder to put them there and the assemblers to deal with them (pretty sure the threadless BB on a $550 bike rocking full Tiagra except for the Mavic wheels helped make that possible), large-diameter threads are easy to cross-thread. Of course, anyone properly competent can avoid that, but properly competent people still buy second-hand frames. And it's a bit harder to avoid cross-threading a BB tap when you're trying to fix such damage...
And what about when the threads are stripped, like on my ally bike (been like that since I bought it)? Got any idea of the lengths I'll have to go to in order to fix that? Bloke I talked to about it mentioned dry ice as part of the plan.
There's no benefit in another 6mm of BB? So stiffness and lightness don't count on a bike, you say.
I haven't had a chance to play with a PF30 BB yet, but I'm tipping the plastic sleeves should reduce the force required, opening the door for creative workarounds... a press (or at least a proper one) may not be necessary.
And these presses, are they heavier and more expensive than a set of BB taps?
And what about when the threads are stripped, like on my ally bike (been like that since I bought it)? Got any idea of the lengths I'll have to go to in order to fix that? Bloke I talked to about it mentioned dry ice as part of the plan.
How is this better? Never mind that they offer no benefits.
I haven't had a chance to play with a PF30 BB yet, but I'm tipping the plastic sleeves should reduce the force required, opening the door for creative workarounds... a press (or at least a proper one) may not be necessary.
And these presses, are they heavier and more expensive than a set of BB taps?
