Monday, December 15, 2008

bottom brackets

my second post: this is about finding the proper bottom bracket for your bicycle. And will be one of several post on learning to fix and maintain our bicyclette. in my case, im converting an 80's japanese road bike into a single speed fixed gear for snowy and rainy weather.

this is the bottom bracket shell of a my little conversion: a 48cm shogan i bought for 65.00 dollars at c.c.c. i took the shimano road parts off for monica's bicycle. shell width is usual 68mm with 1.37 x 24 threading per inch... this is pretty standard for older steal road bikes.

one important exception is older european (french & italian) bottom bracket shells which unscrew in the same direction as pedaling - this can cause the bottom bracket to unscrew itself and even fall out... so keep it in mind when choosing a frame to build. this was a problem on my brothers peugot even after he bought a new sugino bottom bracket built specifically to convert an older style french shell. the same thing happened to another friend who had a cartridge style bottom bracket professionally installed on an older italian road bike he was converting; the cartridge nearly unscrewed itself in less than three days!

at this point you have to decide what type of bottom bracket you want to mount your cranks and pedals on with. i chose a square tapper style bottom bracket; its called a "square tapered" after the ends of the spindle (pictured directly below) which has two squared off tapered ends. there are two popular styles of square taper bottom brackets: cartridge or newer one piece sealed shimano style bottom bracket and older style adjustable cup and cone bottom bracket.

i went with adjustable cup and cone. if you go this way, be ready for the bike shop's attempt to sell you the one peice for convenience sake. like the name implies, it screws in as one piece and you dont really have to mess with it much. this is great if you never plan on looking at it again and you have 20.00 to 50.00 dollars. the problem is once it takes a crap you must replace the entire thing. i have also seen people have problems with these bottom brackets when it comes to older european bikes with reverse threading on their bottom bracket shells.

i got this spindle with one tange cup, one retainer and bearing assembly, and bolt for 9.00 dollars at c.c.c. when i cleaned the old grease off i realized this was a sugino 109mm njs spindle.Photobucket

i got the replacement sugino cone and adjustable cup, bearing set, and mounting bolts for the cranks for 14.00 dollars from the recyclery.Photobucket

suntour superbe cranks tend to take a campy spindle. sheldon brown had suntour cyclones as accepting shimano style 110mm spindle. but i decided to try this sugino 109mm; if nothing else, it gives me options for adjusting the chainline.

style 110mm spindle. but i decided to try 109mm at least it can be used to adjust chainline.

lots of grease of grease, line it up, and its installed!

other side with lock ring

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