How can you tell if you can run 650b

What the title says. I have a Motobecane GravelX3 and want to set up a new wheelset.

Any ideas?

writingjacob wrote:What the title says. I have a Motobecane GravelX3 and want to set up a new wheelset.

Any ideas?

Measure you chainstay clearance about an inch back from where your 700c tire currently is.  Ideally you need it to be at least 10mm wider than the width of 650b tire you want to run.  

It stays the same for a bit, here I come 650b!!

I can't do it as my chain stays are parallel near the seat tube, and just flair out towards the dropout.  Also consider that your BB will be a lot lower with the 650b, so pedal strike may be an issue if you already have a fashionably low BB.

Chain stay clearance, seat stay clearance, crank clearance, BB height

writingjacob wrote:What the title says. I have a Motobecane GravelX3 and want to set up a new wheelset.

Any ideas?

What is the current set up for wheels/tire size?
If you are running a set of 700X40 tires, you can generally run a 650X48.    I have an Open UP and a 3T, and I have run 700X40 or 650X48 on them with no issues.
The variables are:
1) What do the tires actually measure.  Forget what the label says, as some tires run big and some don't. 
2) The inner width of the rim can  also determine the actual width of the tire.
3) What's your comfort label of the tire clearance - space between tire and the frame?  Some people say the certain tires fit, but there is a very little room, and others prefer having a bit more room.  For me, I would like at least 5 mm clearance between the tire and frame/fork..

Check out this page, he pretty much explains everything about figuring out if it will work.

https://www.bikeman.com/bikeman-blogs/650blog/1771-650b-conversion-guidlines

If you are running a set of 700X40 tires, you can generally run a 650X48. ..

Not true.  I don't want to mislead people.  I can run max 700x40, or 650x40.  I just don't have any flair in my chain says (carbon).  Some of my bikes (crimped aluminum), have less clearance with 650, because it moves the wheel behind the crimped section

Obviously the UP and 3T are designed for 650b, but many/most bikes are not - it depends on how the chain stay flairs (and to a lesser degree component interference and seat tube clearance (and in some cases seat stays and brake bridge)).

I'm guessing your rule probably works on the front for, but not for the rear clearance.