B.S.A Twenty folder question

[Yellow_Peril]

...Except the wheels which really aren't the 'standard size' 20" ones, but 500A size.

Yes that's right. 500A is 440 in modern dimensions - most 20 inch wheels are 406 these days. Tyres and tubes are readily available in 440 and you'd find spokes but I reckon new rims might be a lot harder to come by. Steer clear of rusty chromed rims I'd suggest.

Would 451 do the job, or some other similar BMX size not suffice. Or would there be a mudguard issue?

 

[gavr]

Would 451 do the job, or some other similar BMX size not suffice. Or would there be a mudguard issue?

Standard 406 rims are much smaller and you'd likely have a problem with brake reach. 451 is a little bigger than 440 and there you might have trouble with mudguard clearance - that could depend on the actual tyres, I don't have any experience of that I'm afraid.

I believe some BMXs still use 440 but those might look a bit odd on a Kingpin

 

[Yellow_Peril]

Cheers gavr, helpful as ever!