BB sizing help

[jim55]

i obv can measure the shell ( 68 mm) but the width of spindle is what I mean, it's a bike I'm building up from a frame ,what's accepted wisdom ,just fit wheel and measure where the chain will sit? It's a bit of trial and error I'm told is this just the way it is

 

[midlife]

What chain set are you thinking of fitting and to what frame?

Shaun

 

[accountantpete]

Generally the BB axle width is dictated by the chainset - the info should state the type of square taper and the width needed.

If we are talking about older bikes and Campagnolo chainsets it can get a bit complicated.

 

[jim55]

It's an older 531c frame so the size is unknown it's a square taper chainring with 46 teeth Iv got so not massive and need mega clearance re chai stays, is there a standard size

 

[jim55]

Btw it's not campag its a sugino crank

 

[Citius]

Crankset dictates BB axle width. You will need to ID the crankset and look it up - there is no single 'standard' size.

 

[jim55]

Not being cheeky ( as I'm the one asking advice ) but how can crankset dictate width if it essentially a movable part ? Is there any way I can measure anything to get an idea of what I need or is it really just try a few and go for the one that lets ring spin closest to frame ( without fowling chain stay)and work from there

 

[Citius]

Different crank arms/spiders have different offsets. You already know you have a Sugino chainset - just google the model number and find out what BB axle width you need.

 

[jim55]

It's second hand off eBay so I guess il just have to see cos Iv no tech data all I know is it's square taper

 

[Citius]

It will have a model number stamped or cast into it somewhere. Or post a pic.

 

[jim55]

When I get it I will ,I've also just won a set of wheels on eBay they are meant for ss/fixed so once I fit them at least it gives me something to line up to, thanks for the advice btw

 

[Citius]

Can you post a link to the ebay auction (for the cranks) - that might help.

 

[midlife]

Even if its an older bike I'd be tempted to buy a modern square taper bottom bracket like a shimano UN 55 for about 12 quid. Lfgss have a post somewhere on their site which gives info on sizes for single speed.
107 to 111 would be a wild stab in the dark

Shaun

 

[jim55]

Er,,,, dunno how to do that (I'm on iPad) but it's sugino sh
I think this has worked

 

[Citius]

Can't find any reference to Sugino SH - but Sugino's cheapest crankset is the Pista, which takes a 103mm JIS BB - so you could start with one of those.