Singlespeed & Fixed Gear - Italian BB limitations???
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03-17-08, 12:21 PM
Hola. At yesterday's swap meet i picked up and "Italianish" road frame and fork that i would love to build up as a flip-flop (or maybe even a fixie) to use around our hilly little town. It has Campi Horizontal dropouts with 120 mm space between, an elegent reinforced fork with a classic Dura Ace headset, and a 70 mm BB space (no BB though). My first goal is going to be coming up with a suitable drivetrain. Before i get too excited, are their any major limitations to having an Italian BB??? i read that Shimano makes an Italian threaded BB, and if that is so, then i will probably stick with a Japanese drivetrain (but since it will be a total buildup i am not totatlly married to this). BTW, i am sure to have many more dumb questions, but i promise to use the search button and to read (and reread) Sheldon's beta first. Also, any input on potential components would be highly welcome. TID.
There are no real considerations as far as the BB goes except that some sizes and tapers might be difficult to find. FWIW both of my fixed gear bikes use Italian BBs.
03-17-08, 12:40 PM
remember to keep an eye on how tight the bb is, because of the direction of the threading it will probily loosen for the first little while as you ride
03-17-08, 12:41 PM
what ever you end us using, make SURE you tighten the drive side down. Italian BBs are not reverse threaded on the drive side and can work their way loose.
Blue Loctite works for me.
03-17-08, 02:33 PM
Italian BB's are less limiting than english, you can basically adjust the chainline up to about 3mm in each direction by installing it L side in or R side in and using spacers. This doesn't really make them better, they will still unscrew sometimes if not installed "backwards," but it does mean you can adjust the chainline.
phil wood makes italian cups for their bottom brackets. if you're going to put money into this, you might want to consider a titanium bb with alloy cups.
as a bonus, they're micro-adjustable for a perfect chainline.
can someone explain the italian bottom bracket loosening thing, i have never understood it..
i don't get it either. if it was reversed (ie, drive side regular, non-drive side left threaded) british would make more sense, but the idea that an italian drive side comes unscrewed seems illogical to me, as the crank moves in the direction which tightens it. you'd think it would be the non-drive side that comes loose...
From Sheldon (who else?):
"Precession" refers to the tendency of a part subject to rotating stresses to rotate in the opposite direction of the stress rotation. In bicycle applications this becomes a particular issue with the threads that hold pedals into the crank, and the threads that hold the bottom bracket assembly into the frame. See the Pedals entry in this Glossary (http://www.sheldonbrown.com/gloss_p.html#pedal), and Jobst Brandt's article on Left Hand Threads (http://www.sheldonbrown.com/brandt/left.html) on this site for a detailed explanation of precession
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