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Is there anyone that have a more or less precise equivalence table between 650B and 700 wheels diameters depending on the tire chosen
Roll your own, just add twice the tyre section to the rim diameter (622mm for 700C, 584mm for 650B) and you'll be close enough. The actual inflated diameter is a bit more than that and affected by rim width and bead hook height among other factors, but after allowing for squish you end up more that accurate enough for judging the effect of tyre changes on BB drop.
gbj_tester-
Thanks @mdcc_tester, that does result in 18mm drop
700x25 <=> 622+2*25=672mm
650Bx35 <=> 584+35*2=654mm
Considering that I currently run 170mm crank arms and I never had any pedal strike (currently running fixed), switching to 650B and 165mm crank arms woud result in 13mm pedal axis drop which does appear to be quite a bit even if it wouldn't be fixed anymore but with gears, would it be a problem? I assume that this discussion would be much easier with the BB heigh measurement but I do not have it yet. I reckon it would be quite better to run 38mm wide tire to reduce the drop
paulbiche
I have found on the internet (Sheldon website) that
"a 19-622 (700 x 19C) tire would theoretically have exactly the same outside diameter as a 38-584 (650 x 38B)"
Is there anyone that have a more or less precise equivalence table between 650B and 700 wheels diameters depending on the tire chosen? I am considering switching from 700x25 to 650Bx35 and would know approximately by how much the bottom bracket would be lowered.
Thanks in advance