Using a 650b X 47mm tire you have the same outside tire diameter as a 700c road tire, so for your gravel bike you can run the 650b gravel tires for off road riding, and swap to 700c road wheels for road group rides and nothing changes with the geometry or gear ration on the bike.
Rims
Material: Toray T700 / T800
Size: 650B
External Width: 30mm
Internal Width: 24mm
Depth: 24mm / 35mm
Weave: UD / 3K / 12K / Butterfly Pattern
Finish: Matte / Gloss / Non-Paint
Spoke count: 24H / 28H / 32H
Nipple hole: External / Internal
Weight: From 1200g+/-30g
Rider weight limit: 120KG
Max tire pressure: 85PSI
Max spoke tension: 140KGF
Flatness: ≤0.2mm
Roundness: ≤0.3mm
Hubs
Powerway CT43 (308g)
Novatec D411/D412 (329g)
DT Swiss 350 (364g)
DT Swiss 240 (310g)
DT Swiss 180 (284g)
Carbon-Ti X-HUB SP DISC (286g)
Chris King R45D (404g)
Spokes
Sapim CX-Ray
Pillar PSR AERO 1423
Highlights
30mm external wide / 24mm internal wide to fit wider tires.
2.6mm offset helps even out the spoke tension for a more balanced wheel.
Hookless design provides the best impact resistance.
With a nice aero profile and rim shape designed to help crosswind stability.