Rocky Ridge – Sizing

I was looking to buy a Marin Rocky Ridge, had a leg over a large in shop today – way too big, leg over a Medium B17 (no small or med RR’s in the shop but same frame) – a little bit too big. So how small is the small if the medium is 17.5. I am a short ar$e but have a med GT and a 18" Lavadome which have adequate standover height for my short legs. I dont want to look like I am riding a miniature clowns bike, my clown style riding does that by itself.

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