Seeing the rise in interest in new wheel sizes and 11 cogsets sourced it is time to bring up new gear charts for MTB’s.
29ers and 650b wheels have greater circumferences and therefore the distance travelled per crank revolution is modified in proportion.
622mm bead seat rims with 50mm wide tyres (aka 29er) have 11.2% more perimeter than 26 inches wheels (559mm).
As far as for the 650b wheels are concerned (584mm) the discrepance is only 4.5%.
You can still use the old 26 inches chart by multiplying by the factor of 1.112 or 1.045.
Rows: sprocket size | Columns: ring size
26″x1.95-2.0″ (2070 mm wheel circumference). Classic MTB wheel size
27.5/650b (2160 mm wheel circumference)
29er/700c x 50mm (2300 mm wheel circumference)
For further and detailed calculations I suggest this site: