Will a BB adapter similar to this save a frame that's otherwise toast?

[ergott]

I know this doesn't do what I ask. My question is would something similar work to fix a frame that has had it's BB threads knackered?



I imagine a shop tool that would ream out the rest of the bad threading so that you could press one of these in. The two sides screw in together to stay in place. Then you press the outboard BB bearings into it. Is there enough material in let's say an aluminium BB to ream out the threads and still have enough strength for this? I say aluminium since that's the type of frame most likely to have the threads crossed, but this would work for any threaded BB. I think even if there is less material in the BB after boring it out you would gain back the integrity of the BB since the screwed in section will act as a sleeve and support things. I don't know if the welded areas would be the problem.

Am I missing something obvious why this wouldn't work? Perhaps worth pursuing something like this and offering it up?

[Kumo Cycles]

like this?

Grand Cru Threadless Bottom Bracket - Bottom Brackets - Components

[ergott]

Right, but for outboard BB.

[Jake Rosenfeld]

that's rad. you wouldn't even need to fuss with all of the old threading. Just enough to let that in.

I like it

[dashDustin]

Off topic: What press is that?

[ergott]

I believe Wheels Manufacturing.

[sam]

I am going to make an assumtion that the frame is an english BB, if so it is easy to ream and thread to itilian

[ergott]

In one particular situation I saw an alloy BB that I was told by a framebuilder didn't have enough shell material to do so.

[Gattonero]

I believe Wheels Manufacturing.

It is, the basic version but works as well as the "pro", which has a blank zone before the thread in the handle, so when you undo it spinning fast, handles don't fall.

[Gattonero]

I am going to make an assumtion that the frame is an english BB, if so it is easy to ream and thread to itilian

"fairly" easy on alluminium, provided the shell is thick enough. To be done at own's risk, and the very last resort.
Impractical on MTB's, tho. Is there any cranks that would have an Italian b.b.?
.

I know this doesn't do what I ask. My question is would something similar work to fix a frame that has had it's BB threads knackered?

I imagine a shop tool that would ream out the rest of the bad threading so that you could press one of these in. The two sides screw in together to stay in place. Then you press the outboard BB bearings into it. Is there enough material in let's say an aluminium BB to ream out the threads and still have enough strength for this? I say aluminium since that's the type of frame most likely to have the threads crossed, but this would work for any threaded BB. I think even if there is less material in the BB after boring it out you would gain back the integrity of the BB since the screwed in section will act as a sleeve and support things. I don't know if the welded areas would be the problem.

Am I missing something obvious why this wouldn't work? Perhaps worth pursuing something like this and offering it up?

Press-fits BB go on much bigger shell ID.
Trek's BB86 or BB90 have 37.0mm, but are wide enough to not accept any outboard.
A standard BB30 has 42.0, a PF30 has 46.0
Shimano PF ("BB90") has 41.0.
So those Press-fit b.b. that screw onto each other (like Praxis Works) are sized to those standards.
I cannot see how can you ream to 42.0mm a frame that has a 34.7mm ID, as per BSA thread.

[dashDustin]

It is, the basic version but works as well as the "pro", which has a blank zone before the thread in the handle, so when you undo it spinning fast, handles don't fall.

That's really the basic one? Damn. Looks better than I thought.

[blasdelf]

"fairly" easy on alluminium, provided the shell is thick enough. To be done at own's risk, and the very last resort.
Impractical on MTB's, tho. Is there any cranks that would have an Italian b.b.?

I'm pretty sure Pinarello has continued to build such travesties, but remember that the MTB cranks don't care if your external cups are branded for road

So those Press-fit b.b. that screw onto each other (like Praxis Works) are sized to those standards.
I cannot see how can you ream to 42.0mm a frame that has a 34.7mm ID, as per BSA thread.

there's enough room between the 34.7mm threads and a 24mm spindle to concoct a praxis-style solution for a smaller diameter

but I don't see why anyone would bother to develop such a thing given how hard it is to fuck up BSA threads with external cups, and the easier fix of tapping out to Italian threads

[AndyA]

Tap out to Italian, then epoxy in Ceeway's Italian to BSA thread inserts. Done this at least 25 times, zero problems so far

[Gattonero]

That's really the basic one? Damn. Looks better than I thought.

AFAIK the shaft and drifts are the same, the handles change.
It works, can give some pretty good pressure, even too much if you're not careful.
I like the machining of the thread, it is good. You can undo the handles and make them spin a lot, tapping with the fingers

[Gattonero]

I'm pretty sure Pinarello has continued to build such travesties, but remember that the MTB cranks don't care if your external cups are branded for road

...

From 34.7 to 36.0 you're taking off something like 0.65mm which I would take into accounts....
I'm not saying cannot be done, in fact I've done it a few times; just saying that it cannot "always" be done

[ergott]

This is the fancy press. Definitely high quality and worth the money.



I guess so long as there are other/better options, my idea/thought isn't worth pursuing.

[dashDustin]

Yeah, the fancy one I quite dig. Mainly because of the threads. Didn't realize the basic used the same. Makes it a lot more attainable for me.