650B (ETRTO 584mm) is very close to the old English 26×1⅜ (ETRTO 590mm), so that's what I'd go for to fit modern wheel to an old frame. MTB 26" rims are 559mm, i.e. 15.5mm smaller radius than 26×1⅜
@gbj_tester started
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650B (ETRTO 584mm) is very close to the old English 26×1⅜ (ETRTO 590mm), so that's what I'd go for to fit modern wheel to an old frame. MTB 26" rims are 559mm, i.e. 15.5mm smaller radius than 26×1⅜