Bottom bracket shell.... Which do I use? Need experts advise

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Hogaboom

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Hey guys... I'm working on my 3rd build and am tired of using recycled bb shells for one piece cranks. I'm thinking of going with Shimano SRAM bb cause they are inexpensive. What I need to know is what size bb shell do I use? I have found several size bb's and shells from one place but the dims don't add up....

By the way I'm using steel.

Here are some of my choices
SRAM bb
68x110, 68x113, 68x117, 68x117.5, 68x122.5, 68x123, 68x127.5
73x110, 73x113, 73x122.5

Here is a link to a place for the shells
http://www.paragonmachineworks.com/cgi-bin/commerce.cgi?search=action&category=BB02

Or if you guys have another source please let me know. Im am completely open to suggestions. My goal is to keep costs down to a minimum .... I'm a budget builder. All my builds so far have been under $50 by recycling parts from donor bikes with frames built from scratch.

Thanks in advance guys. This place has been very helpful and inspiring at the same time. And yes I will post picks of my builds.

Troy
 
i cant help sorry , but i notice something wierd in your post :?: (bb shells for one piece cranks) :?: :wink:
 
Not sure I'm using the right term "bb shell" this is what I am referring to.


P-Johnson_bare_3.JPG


But just need it as this....

BPC310932.jpg
 
Bottom bracket shells to suit one piece cranks are just a piece of appropriately sized pipe, I have yet to find a supplier of three piece shells so I am just cutting them off donor frames the same way you have been...

Luke.
 
Shell Width will be determined by chainline, which is relative the rear hub spacing.

If you are going with a 135mm rear hub spacing then either a 68mm or 73mm shell will work.

Safe bet would be 68mm as you can still install a 73mm BB and use spacers to get it to fit.
 
I don't understand the width size .... On the SRAM bb... Is it the width is the tapered spindle or the sealed cartridge. Because 113 mm seem to wide if its the cartridge that's close to 4.5 inches....

For the hub I will be using a standard hub or a 3 speed archer ... I'll measure them as see what the width is
 
i think 130 is the distance between the start of the square tapers , and 68 would be how wide the sealed bearing assembly is ... iam i right on this one ?

(btw , about my comment , its because 1piece crank dont use BB and treaded BB frame ... they just use cups and bearings)
 
I understood your comment about the threaded bb and the one piece using cups... Just wasn't sure the term for the shell if that's what it's called even for a one piece crank... Looks like they sell those as well for press in cup too... It has always been easier and less expensive to use a one piece crank, which I like the looks of. But for this build I have in mind I just think I may go for the 3 piece. Was avoiding it due to the increased cost of chain ring, bb and pedals. Guess I could always use a one piece shell and an adapter if I wanna use a 3 piece crank setup... This has been a real learning proses building bike from scratch... What will worl and not work... Gotta love pushing your limits.
 
I'll most likely use the 3G wheel set and since the frame build is big... I'm also 6' 8" got the big feet... To me it is more comfortable in a wider position. It will most likely have 2 chains close to a 200 link chain. My 1st build had 212 links in it. Seems its easy to come in and clear a tire than to be too close to it with a narrow axle. Also the price is right and the only one besides a 68x103 under $15 for the bb... Budget builder here :D
 
Basic info:

It seems to me that you intend to weld or braze a BSA shell into either a new frame or an existing frame that had previously housed an American BB shell...

You'll likely want a 68mm "english thread" (stupid name for BSA), which you found on the paragon site.

Any 68mm or 73mm BB will fit this shell; the 68 and 73mm refers to the dimension between the left and right edges of the BB shell. The other figure is the spindle length. You choose the spindle based on the HUB/CRANK combo you'll be running; you'll want a reasonably straight chainline between the front sprocket and the rear cog. With most cranksets, that 122mm will put the front sprocket pretty far outboard of the cog, if you're using that 3g wheelset. (If you even care at all, the chainline for that 3g wheelset would be roughly 41mm, with a straight (ie, non-dished) cog.)

The intelligent thing to do is figure out what components you'll be using, and then see what crank/BB spindle combo will yield chainline that is fairly close to the chainline requirements of the rear hub. Saving a few bucks on the wrong BB will cost you more in the long run, in my experience.
 
A normal coaster brake hub has a chainline `~40-42mm, most SRAM/Shimano BB are in the 113-118 range with an stated chainline somewhere in the 45-51 range but that's Ok as you'll likely want an offset cog on the hub to get around the wide 3G tire. Sheldon jas a good table of BB's and chainlines here;

http://sheldonbrown.com/bbsize.html
 
Hogaboom said:
I see what ur saying.. So what is a good width if I run a norm size rim or the 57 mm 3G wheel ?
Click to expand...

Depends on the cranks you intend to use. Also, as socal jack states, you might want to run a bit of longer spindle (and a disched cog) to clear an ultra-fat tire.
 

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