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No bearing = no bearing problems



 
 
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  #11  
Old September 6th 19, 04:01 PM posted to rec.bicycles.tech
Tom Kunich[_5_]
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Posts: 764
Default No bearing = no bearing problems

On Thursday, September 5, 2019 at 10:13:49 PM UTC-7, Chalo wrote:
Tom Kunich wrote:

Chalo, What do you call those crank standards that fit the
press-in bearings BBs? They are narrower than the 386.


There are too many Johnny-come-lately nonstandard BB standards to keep track of them all. When I run across one I can't identify (rarely, because my shop is mostly commuters and thrifty upcyclers), I consult a table like Park Tool's.

My last mystery solved was a State brand disc brake CX bike with an eccentric BB. When I pulled the thing out, I thought, "this doesn't look quite big enough to be a tandem eccentric shell" and also "f**k me-- a new superfluous GD BB standard".

Turns out it was a regular BMX/OPC type shell with a couple of big set screws welded on. That customer got a tubular CrMo crank which was cheaper and cooler than what had been in the original plan.


I picked up an FSA crank and it was too narrow for my 386 cups. Eventually I used the rings off of it.
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  #12  
Old September 6th 19, 04:50 PM posted to rec.bicycles.tech
JBeattie
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Posts: 4,174
Default No bearing = no bearing problems

On Friday, September 6, 2019 at 8:01:52 AM UTC-7, Tom Kunich wrote:
On Thursday, September 5, 2019 at 10:13:49 PM UTC-7, Chalo wrote:
Tom Kunich wrote:

Chalo, What do you call those crank standards that fit the
press-in bearings BBs? They are narrower than the 386.


There are too many Johnny-come-lately nonstandard BB standards to keep track of them all. When I run across one I can't identify (rarely, because my shop is mostly commuters and thrifty upcyclers), I consult a table like Park Tool's.

My last mystery solved was a State brand disc brake CX bike with an eccentric BB. When I pulled the thing out, I thought, "this doesn't look quite big enough to be a tandem eccentric shell" and also "f**k me-- a new superfluous GD BB standard".

Turns out it was a regular BMX/OPC type shell with a couple of big set screws welded on. That customer got a tubular CrMo crank which was cheaper and cooler than what had been in the original plan.


I picked up an FSA crank and it was too narrow for my 386 cups. Eventually I used the rings off of it.


That's why you buy a 386 crank for 386 threaded BB.

-- Jay Beattie.
  #13  
Old September 6th 19, 05:01 PM posted to rec.bicycles.tech
Tom Kunich[_5_]
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Posts: 764
Default No bearing = no bearing problems

On Friday, September 6, 2019 at 8:50:59 AM UTC-7, jbeattie wrote:
On Friday, September 6, 2019 at 8:01:52 AM UTC-7, Tom Kunich wrote:
On Thursday, September 5, 2019 at 10:13:49 PM UTC-7, Chalo wrote:
Tom Kunich wrote:

Chalo, What do you call those crank standards that fit the
press-in bearings BBs? They are narrower than the 386.

There are too many Johnny-come-lately nonstandard BB standards to keep track of them all. When I run across one I can't identify (rarely, because my shop is mostly commuters and thrifty upcyclers), I consult a table like Park Tool's.

My last mystery solved was a State brand disc brake CX bike with an eccentric BB. When I pulled the thing out, I thought, "this doesn't look quite big enough to be a tandem eccentric shell" and also "f**k me-- a new superfluous GD BB standard".

Turns out it was a regular BMX/OPC type shell with a couple of big set screws welded on. That customer got a tubular CrMo crank which was cheaper and cooler than what had been in the original plan.


I picked up an FSA crank and it was too narrow for my 386 cups. Eventually I used the rings off of it.


That's why you buy a 386 crank for 386 threaded BB.

-- Jay Beattie.


Didn't you just say that the Q factor was the same on all cranks? Now you're saying that they're different?
  #14  
Old September 6th 19, 05:32 PM posted to rec.bicycles.tech
JBeattie
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Posts: 4,174
Default No bearing = no bearing problems

On Friday, September 6, 2019 at 9:01:16 AM UTC-7, Tom Kunich wrote:
On Friday, September 6, 2019 at 8:50:59 AM UTC-7, jbeattie wrote:
On Friday, September 6, 2019 at 8:01:52 AM UTC-7, Tom Kunich wrote:
On Thursday, September 5, 2019 at 10:13:49 PM UTC-7, Chalo wrote:
Tom Kunich wrote:

Chalo, What do you call those crank standards that fit the
press-in bearings BBs? They are narrower than the 386.

There are too many Johnny-come-lately nonstandard BB standards to keep track of them all. When I run across one I can't identify (rarely, because my shop is mostly commuters and thrifty upcyclers), I consult a table like Park Tool's.

My last mystery solved was a State brand disc brake CX bike with an eccentric BB. When I pulled the thing out, I thought, "this doesn't look quite big enough to be a tandem eccentric shell" and also "f**k me-- a new superfluous GD BB standard".

Turns out it was a regular BMX/OPC type shell with a couple of big set screws welded on. That customer got a tubular CrMo crank which was cheaper and cooler than what had been in the original plan.

I picked up an FSA crank and it was too narrow for my 386 cups. Eventually I used the rings off of it.


That's why you buy a 386 crank for 386 threaded BB.

-- Jay Beattie.


Didn't you just say that the Q factor was the same on all cranks? Now you're saying that they're different?


I said nothing about the Q-factor of a FSA 386 crank. I said the Q-factor on a 24mm spindle Shimano Hollowtech was the same regardless of what BB you used. It is a function of crank design and axle/spindle length.

And, had you looked, you would know that the Q-factor for FSA 386 crank IS the same as the FSA BB30 crank because the 386 crank arms are straighter. https://bikerumor.com/2011/12/22/fsa...rison-weights/ 146mm for both cranks. Shimano FC6800 is 146.6, or just 146 depending on where you look. Notwithstanding the same Q-factor, a BB30 crank (which is based on a 68mm shell standard) will not fit a BB386, as you learned from your shopping experience.

-- Jay Beattie.
 




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