Bottom Bracket Conversions

[Phil Fink]

I have never built-up a bike using a frame with an Italian threaded bottom bracket before.
Is there a way to covert those to use a more common (I think?) BMX crank and Sprocket.
Do the Italian bearings and cups interface with other spindle arrangements?

I am wondering if a different spindle would allow me to somehow use a more vintage sprocket; (perhaps if it would accommodate a drive-bolt type crankset)?

Would the options be the different or the same with frame with an English 1.37 x 24 threaded bottom bracket?

Maybe it would not be possible, since the foreign cups face inward but the American cups face outward?

 

[mikeeebikey]

In short the answer is "yes." Yes they do make bottom brackets to fit 3 piece bmx cranks. I run a bunch of different brands, race face and Redline make the price point for value.

 

[us56456712]

In short the answer is "yes." Yes they do make bottom brackets to fit 3 piece bmx cranks. I run a bunch of different brands, race face and Redline make the price point for value.

I have never built-up a bike using a frame with an Italian threaded bottom bracket before.
Is there a way to covert those to use a more common (I think?) BMX crank and Sprocket.
Do the Italian bearings and cups interface with other spindle arrangements?

I am wondering if a different spindle would allow me to somehow use a more vintage sprocket; (perhaps if it would accommodate a drive-bolt type crankset)?

Would the options be the different or the same with frame with an English 1.37 x 24 threaded bottom bracket?

Maybe it would not be possible, since the foreign cups face inward but the American cups face outward?

Italian bb are obsolete, hardly ever used now as they are a slightly inferior design. Both sides are righty tightly so they tend to come loose. So, different both right hand threading, different wider spindle spacing and wider bb shell, different thread pitch than standard bsa. Can’t do anything with it except use original parts. Spindle off set is a shot in the dark as most stuff for sale has no specs. There are new design bb sets that screw in and and are pretty adjustable but I’m not aware of any that will work with the Italian bb. Perhaps the BMX conversion will work but with the weird spindle bearing spacing Im at a loss to figure out how that would be possible? I usually spend a couple of months buying parts and throwing some of them away trying to fit a drive train to an unbuilt Italian frame. These bikes are usually older and use one inch fork tubes which will become harder to find in years to come. But a lot of older Italian bicycles are highest quality, Cologno, Somex and many others.

 

[RustySprockets]

I think what you need is this:

https://velo-orange.com/products/grand-cru-threadless-bottom-brackets

The description straight-up says 'does not work with Italian.'

 

[macncheese]

The description straight-up says 'does not work with Italian.'

Whoops! Deleted.

 

[RustySprockets]

No biggie. I just didn't want him to buy a $70 BB, only to be disappointed.

 

[Phil Fink]

Thanks all. I actually did look at that Gran Cru, thinking that it might look grand. So I may have some measuring to do (effective BB width 68+), maybe some math calculations (spindle length), but I am reluctant to spend much on an item if not described too well.
For the spindle length, I should probably be more concerned about the distance between the two fixed cones; usually the overall length, or the BB width it fits, might be specified.
I also understand the precession concept about threads, and am using an off-the-shelf Velobia Finland adapter (one size only) converting wrong-wrong to righty-righty (only 1/2 wrong).