Which Bottom Bracket for De Rosa SLX ??

[roadiesean]

Hi all, I have a conundrum as my new De Rosa SLX frame seems to have a different BB diameter than my Colnago Master Olympic and the Record BB that I have doesn't fit, it just slides straight through (ie the De Rosa is a larger diameter)

Now this is the first time I have come across this, with any bike other than a Cannondale with BB30, I always thought that the diameters of the BB's of all road bikes were the same (normally the thread may be different - Italian vs English) but this is just wierd......

Did they change the diameters of the BB's when they moved to cartridge BB's (ie sealed units) or something, as I think the DeRosa is older than the Master O.

Can anyone help me out here ??? Confused indeed......

Thanks
Sean

 

[FluffyChicken]

Italian bottom bracket. 70mm wide ? it is also a larger shell.

My best guess.


edit
err i'll add this
http://www.sheldonbrown.com/gloss_i-k.html#italian
oh and this
http://en.wikipedia.org/wiki/Bottom_bra ... _threading

 

[roadiesean]

Well that explains it, but what it doesn't explain is why does the BB fit my Colnago ??? Wierd.....

Thanks heaps

 

[FluffyChicken]

I know nothing about these bikes, but probably because it just uses a different size bottom bracket e.g. the one you have ?

or am I missing something :xmas-big-grin:

 

[roadiesean]

Because one would assume that the diameter of my Italian Colnago and Italian De Rosa of similar vintages would be the same !

 

[fiks]

It seems your De Rosa has a British threaded BB and your Colnago has Italian.

AFAIK all Colnagos have an Italian BB, dunno about De Rosa though.

An Italian BB shell is both larger in diameter and width.

 

[roadiesean]

This is what is wierd, its definitely Italian, 70mm wide but 36mm diameter. My BB is also Italian

But a smaller diameter. Do Italian BB's come in different diameters ?

 

[roadiesean]

Doh.....idiot !!!!! (me that is) of course the De Rosa is Italian....the problem is ....well.....my "Italian" BB is......well, kind of English.....

Mystery solved, thanks for all your help guys. I'll just go and boil my head. What a muppet !

 

[njgoldby]

I have a similar question and am eagerly awaiting a conclusion.
I only new the thread and width of body were different and obviously the axle length depends on what cranks you intend to fit. From what you say it does seem that the diameters differ as well. I will have to borrow a caliper to check what I took off.
Does the age of the frame prehaps have a bearing on Diameter?

 

[orbeas]

the other difference is that the italian b/brackets are both R/hand threads on both sides of the b/bracket
english are l/hand on the chainwheel side and r/hand on the crank side