I'm looking to buy my first MTB and I had an online calculator tell me to get a 17.5". My measurements are height: 177cm and leg 76cm.

Thing is, I found a bike that I REALLY want, but it's the last one and it's a 15.5" hence the good price. If I don't get this particular one I'll have to get something significantly lower spec as this is massively discounted.

I don't intend on doing really long rides ever. Maybe 2 hours max.

1.5" difference doesn't seem that much.. Will this be ok or am I about to waste allot of money?