Crank width and BB question

Posted on Mon 27th, July 2009

• #1

rocker9455

Hey guys,
Not sure whether this is a silly question but here goes:
is it possible to work out an approximate figure for a bb length from knowing your crank width?
• #2

hippy

Wtf

You mean work out bb width whilst your cranks are still fitted?

Measure total width, subtract crank arm widths and a little bit more and you will still have a pretty ROUGH estimate.

If it's a modern bike it'll most likely be 68mm wide

Just remove the cranks. Or you might be able to read off the bb case if you have a slotted bb shell like the old Raleighs
• #3

rocker9455

nooo! i mean i have a BB in my frame, the cranks are off and i was just wondering whether i could work out which BB i would need (i.e. replace the one i currently have in there) to get a good chain line (the crank is a road double.)
• #4

Cohen

if the bb you have in there is the right length for the cranks you will be using, then just measure it end to end?!
• #5

rocker9455

ok, il do that ;) so theres no proper way to get a good estimate apart from trying
• #6

hippy

Why would you estimate it if you can hold a ruler to it and get it accurate?!?!?!
• #7

rocker9455

erm, ok im hideously confused, oh wait no figured it out, that was a silly question xD

Post a reply
- Bold
- Italics
- Link
- Image
- List
- Quote
- code
- Preview
Formatting Help

Don't worry about formatting, just type in the text and we'll take care of making sense of it. We will auto-convert links, and if you put asterisks around words we will make them bold.

Tips:

Create headers by underlining text with ==== or ----

To *italicise* text put one asterisk each side of the word

To **bold** text put two asterisks each side of the word

Embed images by entering:
![](https://www.google.co.uk/images/srpr/logo4w.png)
That's the hard one: exclamation, square brackets and then the URL to the image in brackets.

* Create lists by starting lines with asterisks

1. Create numbered lists by starting lines with a number and a dot

> Quote text by starting lines with >

Mention another user by @username

For syntax highlighting, surround the code block with three backticks:

```
Your code goes here
```
Just like Github, a blank line must precede a code block.

If you upload more than 5 files we will display all attachments as thumbnails.

For a full reference visit the Markdown syntax.