I'm getting ready to do my second 650B conversion. Both frame candidates (of which I have yet yet to pick which one I will build up) do NOT have bottom brackets included. I realize the size of the bottom bracket it dependent upon the crank/chain ring choice. I reckon it's easy if I buy a new one (say this cool Velo-Orange on special: https://store.velo-orange.com/index.p...-crankset.html) the specs tell me which BB size to get... BUT if I decide to scrounge one out of the bin at the earn-a-bike shop I volunteer at (an older but very serviceable one) how do I determine what size to use? For cool quotient, there is an older(age unknown) Shimano Tourney or a decent Sugino DX (I think... don't have them in front of me). Anyway... is there some online database with a list of cranks and their BB size requirements? I like the idea of getting a build together with bits and pieces and saving some $ and reusing stuff.

Frame has a 130MM width in back and will probably be an 8 speed - POSSIBLY a 1 x8 eventually (as it will be an urban/commuter)

thanks for any sage advice

Sheldon Brown did this chart: https://www.sheldonbrown.com/bbsize.html

It understandably can't cover the zillion possibilities, but it's a start.

Neal

Here is another chart that may have some use to you although a little dated.I left a direct link to my Sutherland's manual at photo bucket also

Glenn

https://s299.photobucket.com/albums/m...pair%20manual/

Sutherland's 6th manual has a fairly comprehensive database of bottom bracket data; more comprehensive, and I think easier to use than the 4th edition. Using it requires spending a little time reading their instructions carefully. It even has factors for cup thickness, so you can mix and match cups and spindles that weren't a matched set -- that is if you believe in the data.

There are several variables:
what chainline do you want to end up with for your rear cogset
how big is the spindle end (ISO, Campy, or JIS "standard")
how wide is the bottom bracket housing
how long is the spindle overall
how thick are the cups (really, the distance between fixed cup flange and the bearing track in the cup) -- this is what "cup factor" is about
is the spindle offset on the right side (longer than left from bearing surfaces) and if so how much
how big are the sockets in the crank arms nominally (which "standard")
how worn are the sockets in the crank arms
what are the original designed spindle length/offset/standard that was required to give you a certain chainline (basically, what's the relationship between the end of the spindle when tightened and the chainring mounting surfaces on the left crank, though nobody seems to provide that data, except implicitly)

That's obviously a lot of variables, so it's not a simple plug-and-play solution unless you buy a matched set. Sutherlands, if they cover spindles/cups you have access to, is a good place to start, but you'll only really solve it by trial-and-error.

Shims are available for the fixed cup (to push everything to the right side a bit), though you can't go very far with that, without running out of lockring threads on the adjustable cup.

The next question is "where is Sutherland's 6th?" -- just Google it.

The info above is from the third ED, I haven't down loaded the 5th ed that I have yet to Photobucket. I would love to get the 6th and 7th ed's to add.

Glenn