Speed concept fit?

Yes, no, maybe….

Height is a crappy indicator of bike fit… core strength, flexibility, upper/lower leg length, upper/lower body will all result in quite a different fit. Not only could it mean that the SC may be too small for you, but if could mean that the SC is just plain the wrong geometry for you.

Now, if the price is a crazy good as you describe it, then you're running a minimal risk. If it does't fit you well, then you could potentially sell it for the same price, or at a very slight loss. If the price is not as good as you think it is, then the risk is of course greater.

I would not do it. Crazy good deals are everywhere, when it comes to used bikes. However, if I was you - got to a speed concept dealer - try on a Medium - and see what you think. However - DO NOT slam yourself on a bike that does not fit because you gotta have it now - no matter your budget.

I have been through this time and time again - and made a couple of mistakes and hasty decisions myself - and truly, your good deal if it does not fit ... costs you money, not save money.

Take a deep breath ... truly, get fit (which I know takes time and is boring yawn) ... and make a wise decision.