Different Strokes For Different Yokes

When I go from riding my fixed bike to my BMX I'm always surprised by how much room I'm given. I've always put it down to a combination of the erratic pedaling, wide bars and the general publics perception of how a BMXer might think/act compared to the smooth, fast and streamlined riding position on my fixed gear. I do tend to ride all over the road on my BMX though.

In the TFL study "Drivers' Perception of Cyclists" (TRL 549) they examined various factors (different bikes, different clothes, different riding styles etc ) that might effect motorist behaviour towards cyclists. Here's a few paras of conclusions from the qualitative research:

Drivers consistently awarded space, speed reduction and more caution to the stunt cyclist than to the professional cyclist or the everyday cyclist (although the differences between the everyday cyclist and professional cyclist were marginal). It was also found that, with the everyday and professional cyclists, drivers were more likely to concede speed than space and more likely to concede space than caution. Similar proportions of all driver types said they would drive more cautiously, slow down and give more room when overtaking the stunt cyclist – the general impression being that this cyclist is less predictable and thereforewarrants special attention.

However, this summary of the findings does not disentangle what factors are doing what to motorists' perceptions and how these different perceptions translate into actual behaviour in a road environment.

Back to the OP. When I used to ride a folding bike regularly, I did notice a change in others' behaviour, but it was mostly from cyclists (who seemed to take umbrage at being passed by someone with small wheels) and pedestrians who would laugh, point, stare, or talk to me about the bike (that was before folders became more popular though).

However, I can't say I noticed too much difference in general road user behaviour when I rode a Brompton, Trek, or Birdy. That said, I would contend that there is a discernible change in the way motorists treat you on the road when you ride an unusual bike, i.e a recumbent, a unicycle, or a laden cargo bike..