My chainstays on my "touring" bike, are 430mm, and with 44 size shoes and cranks of 175mm, and full panniers, I have no issues with heel strike. Now I'm not saying I would want them any shorter, nor am I saying that a little longer may not be better but given that in the past I have toured easily on bikes with 440 and less chainstays, it would not be a deciding factor in ruling the bike out for me personally.