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Im confused about PF30 bottom bracket

Old 07-09-20, 09:06 PM
  #1  
Akjam101
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Im confused about PF30 bottom bracket

I accidentally bought a PF30 a few months ago while building a bike and I didn't return it. So now I'm planning to build another bike using that PF30. I'm not sure if it will fit my new frame (https://www.chainreactioncycles.com/.../rp-prod130452) because it says the bottom bracket it 73mm BSA while I measured my FSA PF30 and its bearing cups are 46mm, but online people say that a PF30 is either 68mm or 73mm, and if it is 73mm it should fit this frame right? Maybe I'm just measuring my bottom bracket wrong. I'm building this for my mom's bday so I don't wanna mess it up as I did with my bike.
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Old 07-09-20, 09:28 PM
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Your frame has a threaded (BSA) 73mm bottom bracket shell which will not work with your PF30 (Press Fit 30) BB. https://wheelsmfg.com/bb-standards https://www.bikeradar.com/advice/buy...ket-standards/
You also need to have the BB that matches your crankset so check to see if the crank you use has BSA 73mm option.

Last edited by Crankycrank; 07-09-20 at 09:34 PM.
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Old 07-09-20, 10:48 PM
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Akjam101
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Originally Posted by Crankycrank View Post
Your frame has a threaded (BSA) 73mm bottom bracket shell which will not work with your PF30 (Press Fit 30) BB. https://wheelsmfg.com/bb-standards https://www.bikeradar.com/advice/buy...ket-standards/
You also need to have the BB that matches your crankset so check to see if the crank you use has BSA 73mm option.
How do you know its threaded? And if not PF30 then what BB can fit? would this BB work? https://www.worldwidecyclery.com/pro...bottom-bracket
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Old 07-10-20, 04:44 AM
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[QUOTE=Akjam101;21579256]How do you know its threaded?.../QUOTE]
"Bottom Bracket: 73mm BSA"
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Old 07-10-20, 08:15 AM
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Crankycrank
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Originally Posted by Akjam101 View Post
How do you know its threaded?
First, read the links I provided in post #2 which will answer all your questions. BSA (British Small Arms also referred to as "English Threaded") is a threaded standard. https://en.wikipedia.org/wiki/Birmin...l_Arms_Company The link you provided for the Shimano Hollowtech BB will work with a Shimano Hollowtech crank and maybe some others with the same dimensions.

Last edited by Crankycrank; 07-10-20 at 08:20 AM.
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Old 07-10-20, 08:25 AM
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PF is Press Fit ... It's the wrong BB for a threaded BB frame..External BB come with the crankset.
73 is a MTB type.
30 is the bearing mm ID. that's the measurement of the tube spindle that slips into those bearings..

Last edited by fietsbob; 07-10-20 at 10:20 AM.
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Old 07-10-20, 08:36 AM
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Originally Posted by Akjam101 View Post
I accidentally bought a PF30 a few months ago while building a bike and I didn't return it. So now I'm planning to build another bike using that PF30. I'm not sure if it will fit my new frame (https://www.chainreactioncycles.com/.../rp-prod130452) because it says the bottom bracket it 73mm BSA while I measured my FSA PF30 and its bearing cups are 46mm, but online people say that a PF30 is either 68mm or 73mm, and if it is 73mm it should fit this frame right? Maybe I'm just measuring my bottom bracket wrong. I'm building this for my mom's bday so I don't wanna mess it up as I did with my bike.
The 68mm and 73mm numbers just relate to the shell width of a frame. It doesn't have anything to do with compatibilty between BSA and PF30 which are completely different from each other. BSA is not cross compatible with PF30 even if they are 68mm or 73mm.

BSA shells come in 68mm and 73mm.

PF30 shells come in 68mm and 73mm.

But that's where it ends.

68mm is road, 73mm is MTB.

The most important measurement for PF30 is the diameter which is 46mm.

BSA is 34.7mm diameter. But is more commonly referred to as 1.37 inch x 24tpi (thread size)

Originally Posted by Akjam101 View Post
Technically it will work but it's for a Shimano road crank and road frame with a 68mm shell. The Brand X frame is 73mm shell. So the middle protective sleeve will be 5mm too short. The middle sleeve isn't absolutely neccesary. The BB will work without it but then there less protection of the spindle

Instead buy the Hollowtech MTB 73mm english threaded BB if you are fitting a Shimano Hollowtech mtb crank.

What crankset are you planning to fit ? That is the detail left out. PF30 BB's can come in many types like either BB30/PF30/HT2/GXP cranks etc. So more info is needed. If you are trying to fit a 30mm crank into a BSA frame then you need a BSA30 BB and your cranks spindle needs to be long enough to accommodate the extra width of the BSA30 BB.

Last edited by trailflow1; 07-10-20 at 11:51 AM.
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Old 07-10-20, 09:33 AM
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figure out what crank you are using based on how many speeds etc then get the matching BB that fits the 73mm BSA/.English standard Crank first then matching BB not BB and match crank. Cranksets have different spindle size or may not have attached spindle but use the spindle that is part of the BB assembly

So what Crankset are you using?
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Old 07-10-20, 07:21 PM
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Originally Posted by trailflow1 View Post
The 68mm and 73mm numbers just relate to the shell width of a frame. It doesn't have anything to do with compatibilty between BSA and PF30 which are completely different from each other. BSA is not cross compatible with PF30 even if they are 68mm or 73mm.

BSA shells come in 68mm and 73mm.

PF30 shells come in 68mm and 73mm.

But that's where it ends.

68mm is road, 73mm is MTB.

The most important measurement for PF30 is the diameter which is 46mm.

BSA is 34.7mm diameter. But is more commonly referred to as 1.37 inch x 24tpi (thread size)



Technically it will work but it's for a Shimano road crank and road frame with a 68mm shell. The Brand X frame is 73mm shell. So the middle protective sleeve will be 5mm too short. The middle sleeve isn't absolutely neccesary. The BB will work without it but then there less protection of the spindle

Instead buy the Hollowtech MTB 73mm english threaded BB if you are fitting a Shimano Hollowtech mtb crank.

What crankset are you planning to fit ? That is the detail left out. PF30 BB's can come in many types like either BB30/PF30/HT2/GXP cranks etc. So more info is needed. If you are trying to fit a 30mm crank into a BSA frame then you need a BSA30 BB and your cranks spindle needs to be long enough to accommodate the extra width of the BSA30 BB.
Ok, thanks. This was actually really helpful. I found this BB (https://www.coloradocyclist.com/shim...YaAlrbEALw_wcB) but it says its both 68mm and 73mm, how does that work. If I can use this BB I plan to buy this crankset for it, will this crank be compatible with my BB?(https://www.benscycle.com/Shimano-Al...kaAlIBEALw_wcB)
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Old 07-10-20, 07:23 PM
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Originally Posted by squirtdad View Post
figure out what crank you are using based on how many speeds etc then get the matching BB that fits the 73mm BSA/.English standard Crank first then matching BB not BB and match crank. Cranksets have different spindle size or may not have attached spindle but use the spindle that is part of the BB assembly

So what Crankset are you using?
Im planning to use this crank with the new Hollotech BB, will it be compatible? (https://www.benscycle.com/Shimano-Al...kaAlIBEALw_wcB)
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Old 07-10-20, 07:32 PM
  #11  
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https://bike.shimano.com/en-EU/produ.../FC-M4050.html
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Old 07-11-20, 10:01 AM
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Originally Posted by Akjam101 View Post
Ok, thanks. This was actually really helpful. I found this BB (https://www.coloradocyclist.com/shim...YaAlrbEALw_wcB) but it says its both 68mm and 73mm, how does that work.
Don't worry about it. It will work fine. Some older 90's/2000's mtb frames use a 68mm shell. And you'll find some modern steel mtb/touring frames around today that have a 68mm shell. The BB above will come with a set of spacers to fill the 68mm out to 73mm. But in your case they are not needed.

Originally Posted by Akjam101 View Post
If I can use this BB I plan to buy this crankset for it, will this crank be compatible with my BB?(https://www.benscycle.com/Shimano-Al...kaAlIBEALw_wcB)
Yes. The Alivio M4050 crank is 100% compatible with the XT MT800 BB.

Last edited by trailflow1; 07-11-20 at 10:07 AM.
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Old 07-11-20, 10:21 AM
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Akjam101
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Originally Posted by trailflow1 View Post
Don't worry about it. It will work fine. Some older 90's/2000's mtb frames use a 68mm shell. And you'll find some modern steel mtb/touring frames around today that have a 68mm shell. The BB above will come with a set of spacers to fill the 68mm out to 73mm. But in your case they are not needed.



Yes. The Alivio M4050 crank is 100% compatible with the XT MT800 BB.
ok, thanks.
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