BB width for STX Chainset

[drcarlos]

Got an STX chainset inbound for the Hahanna and the original BB is wornout so just checking the 68/122 UN54 I have spotted will fit as the orginal was this size but the chainset was alivio.

Carl.

 

[hydorah]

That should be alright

Just matched up one of each, they are dimensionally IDENTICAL

STX's rings Just seems to be a different colour! Looks a lot nicer though

 

[drcarlos]

Thanks, nothing like having both to make a comparison.

Hahanna frame is full Tange cr-mo and deserved much better kit. have nearly everything i need to do the build now.

Carl.

 

[hydorah]

Thanks, nothing like having both to make a comparison.

Hahanna frame is full Tange cr-mo and deserved much better kit. have nearly everything i need to do the build now.

Carl.

Such a great thing about this site:

There is always someone who can give you the actual answer

Bike sounds nice man! Are you posting your build?

 

[mattbrown]

sheldon brown says about 110-113 in length.

 

[Tazio]

I have to admit that BB width confuses me and I'm still not sure how to work it out. For example I'm about to refurb a bike. The original BB axle was 113mm with a 73mm shell and a Sugino Impel crank. At some point before I got the bike it became a Shimano crank with the same size (maybe the same one) BB. I now want to change it to a Coda crank that I have that I want to use. Same size BB?

 

[Xesh]

Got an STX chainset inbound for the Hahanna and the original BB is wornout so just checking the 68/122 UN54 I have spotted will fit as the orginal was this size but the chainset was alivio.

Carl.

122mm is too long for an STX. 113mm is your friend.

Come to think of it I've never known Alivio to use a 122mm either..... :?

 

[drcarlos]

Couldn't see anything on Sheldons site, but I will put the verniers on the original I kept (for sizing) to confirm. It may just be my memory letting me down and a bit of wishful thinking .
It doesn't really matter as corduroyboy has popped in a decent condition BB with the chainset now .

Carl.

 

[Tad]

I have to admit that BB width confuses me and I'm still not sure how to work it out. For example I'm about to refurb a bike. The original BB axle was 113mm with a 73mm shell and a Sugino Impel crank. At some point before I got the bike it became a Shimano crank with the same size (maybe the same one) BB. I now want to change it to a Coda crank that I have that I want to use. Same size BB?

The BB shell width will be specific to the frame and is independant of the crank used.

The spindle length is specific to the crank you're going to be using. It may be a coincidence that it will be the same size as the one that's currently fitted but don't bet on it.

This is usualy a good place to start to find what length spindle you need for your cranks, unfortunately Coda aren't listed.

http://www.sheldonbrown.com/bbsize.html

Post up the model of the crank you're using and someone is bound to know what length BB spindle you need.

The other option is to fit it to the existing BB and go from there, the chain line will indicate whether it's the right length or whether you need to go shorter or longer.

 

[hydorah]

BB Shizz

If you had an alivio on there and all was well

the STX is the same dimensions so match 'em up

To work out (roughly) whether a crank will work without change, fit on the bike

If it's too close too (or grinds against the chainstay) you need a wider BB

It it sticks out farther that the old one did, you need need a narrower BB

- They are often marked with the axle widths usually but calipers are indespensible, and cheap

- Matching up what worked before is always good, though

I didn't worry about your numbers as you've done a match up

But fixies/matt brown/sheldon are right I measured the Apline Starts AST140 that that STX crank came off and it has a 110mm axle width

This is measured overall taper end to taper end

Incedentally the SHELL width was 68mm (just frame fitment, nothing to do with arms. this frams could support any type of arms with the appropriate axle)

Agian as Fixies says: BB AXLE width isn't independent of the arms used for example if you wanted to use an old school biopace chainset on your Kona, where the arms are flat, you would need a wider axle

But you can use cranks of the same type interchangeably

But if you wnated to fit an older crank on 'modern' bike or vice versa you would need a wider/narrower axle

The difference is massively obvious side by side:

More modern cranks are low profile (narrower axles) the intent is cheifly to save weight on solid steel axle, secondary aim is more room

So what worked for you Alivio will work for your STX, just match 'em up right