700c to 650b conversion

Posted on Tue 29th, December 2020

• #1

SebastianAitch

Converting my partner's road bike to something more comfortable, gravel worthy.

What's the best way to calculate 700c to 650b. I've used the calculators online and the circumference is fine but none seem to take into consideration the tyre width/bulge once it's inflated. Any tips or help would be much appreciated.

Currently the wheels run 700c x 28mm with a fork width of 35mm & rear dropout width of 33mm ( at their narrowest point)

Cheers
• #2

Tijs in reply to @SebastianAitch

Currently the wheels run 700c x 28mm with a fork width of 35mm & rear dropout width of 33mm ( at their narrowest point)

What make and model? If it's a 'proper' road bike you can't really convert it.

Main issue will be not enough room in the chain stay area. Better off selling it and buying for example a (650b compatible) gravel bike.
• #3

SebastianAitch

Liv Avail SL1 2018
• #4

Tijs in reply to @SebastianAitch

Liv Avail SL1 2018

Converting that to 650b is not gonna do you any good.

You're not going to be able to squeeze a lot more rubber in there, and with the smaller 650b wheels you're going to mess up the geometry (bb height, fork trail, etc). I would look into swapping this out of something else.
• #5

SebastianAitch in reply to @Tijs

Cheers for the heads up! As I had thought but not hoped.

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.