Perhaps an obvious question but I’ve never really paid much attention to the whole wheel size chat.

Geometry – for example head tube angle. Is a 68 deg 650b a similar feel to a 68 deg 26in? Or does it ride slacker or steeper? Seems that most 650/29 bikes have a steeper head angle than 26s – so does a 68deg 650 ride like a 67deg 26in?

I’ve just re read what I typed and I’m not sure I even understand my own question but hopefully someone does 😕

Kind of.

For a given head angle and fork offset the larger the wheel size, the more trail you get which does affect steering feel.

yes but the difference between 650b and 26 is so small that the effect on the angle can be less than one degree and nearer zero?

And a 68 degree head angle is 68 degrees regardless of wheel size but unless the fork offset is changed then the 650B will have very slightly more trail than the 26″ (depending on tyre size) I wouldn’t be able to tell the difference, probably.

Good synopsis here:

http://www.pinkbike.com/news/To-the-Point-Wheel-Diameter-VS-Fork-Offset.html