If 650b are 27.5", then "normal" wheels are 26.5". I reckon you also need to use a tyre bigger than 2.0" on them for them to have an point at all, as otherwise you just run a 2.5" tyre on standard size wheels for the same outside diameter. Not that anybody buying one is likely to care whether or not there is any point to one 🙄
I run a 2.3 on mine, they are a fair bit bigger than any 26" tyre I've riddeen with.
My 650B rolls like a 29er but handles like a 26er in the twisty stuff. Best of both worlds ime. Drawbacks are: lack of rims and tyres in the UK making any purchase an expensive one. if you're the type of rider that changes tyres regulary or relys on tyres rather than skill then don't bother otherwise you'll be spending more on tyres than the frame 😉
Also the acceleration thing is a load of B0l0x, it makes no noticable difference at all.
