I agree. Regarding very recent posts, it changes my perception; I had thought the Helix would ride much better than the Brompton, both due to much larger diameter tires, but also thinking the Brompton would be limited in tire width more than the Helix. I don't know about frame clearance on the Brompton for wide tires, but it seems that the selection of 24" tires for the Helix is quite limited. Understandable, given that it's not used for mountain bikes or any racing, given that 507 has been used mostly for juvenile bikes (and I was not aware it was 507, I thought one of the other standards).