I'm gonna come right out and say it, I like "long" chainstays on my mountain bike. I'm tired of being sold a bill of goods that bikes with short stays climb better and get better traction. It's B.S. in the sizes of bikes I ride. At 6'4" the bike I'm on has the same length stays as a bike built for a person 5'4" and that's crap. I realize that in the mountain bike market that advertised chainstay length has replaced standover for the most meaningless and yet most scrutinized dimension on production bikes. Yes I could get a custom bike made, but there aren't many of those being done in full suspension. Those that do are buying rear ends from excellent suppliers like Ventana and those all come with the same length stays, regardless of size. I'll dig a little further into why I dislike short stays to explain my belief. Take a bike that's made for the average 5'10" guy and drop a plumb line down from the sit bone area of the seat and notice where it falls in relation to the contact patch. Probably somewhere just in front of or towards the front of the contact patch of the tire. Now lift the front of the bike to replicate a 10-20% climb and see where the plumb line falls in relation to the contact patch. In the smaller sizes, it's probably still within the contact patch. In the bigger sizes (and not as big as you'd think) when you drop the plumb line on level ground, it falls at best towards the back of the contact patch and quite often behind it. When the bike is pointed uphill, that point now falls further and further behind the contact patch, and it gets worse and worse the steeper the climb. Meaning every steep, loose climb is a delicate balance of resisting spinning out and looping the front end. The taller a rider is, the higher the center of gravity is and the more exaggerated this tendency is.
Now I understand all bicycle geometry is an exercise in compromise. Long chainstays have their own draw backs and I'm fully aware of them. I just get tired of hearing how shortening a mountainbike's chainstays is always a benefit and has virtually no downsides, especially when someone tries and spout the B.S. that they climb the steeps better. Ever look at a motor bike designed for hillclimbs? Sure they are an extreme, but look how silly long their swing are.
O.K. Rant over. Thanks guys. I look forward to hearing everyone else's take on this. Cheers.