I've built a 456 a few weeks back and the riding position feels wrong. It's a medium, inline post and 90mm stem. Even with the saddle pushed back it feels to short. Are these frames designed to be run with a layback post so you can run the shorter stems that the frames are designed for? Surely though this makes it worse when climbing, with your weight too far back?
My other bike is a 575, again medium and inline post, 110mm stem.
I understand the benefits of the shorter stem in terms of handling, but I'm struggling with how it effects riding position.
I'm 5'8" so if anything I would b borderline for both bikes in their respective sizes, yet the Yeti is spot on.

Try a longer stem? I ride longer stems than most, doesn't slow me down though I am not rad.

Do you have a very long body or arms for your height? I'm 5'8" and ride a 16" with an inline post and a 65mm stem.

How does the effective top tube compare to the 575?

How about a pic of both?

I run a layback on mine (older EA70) and a 70mm stem and it's fine for this 5'11" bloke (18" frame). I also have a 16" as a spare and that's okay.

The 456 has a decent long top tube so if it still feels short then I suggest either you have a odd shaped body (?) or maybe you're just used to a more stretched-out XC position.

Measure the yeti vs the on one, saddle to bars.

I'm 5'7" and have a 16' 456. Running with a 60mm stem, backswept bars and an in-line post it's just short enough … On Ones do have a pretty long TT.

I do however have long legs and a short body, so as above perhaps you're the other way.

wider bars will straighten your arms out, and give a roomier feel to the bike. As will a longer stem, with the same width bars, unsurprisingly.
A short stem wil put less weight over the front wheel and increase steering feedback from the trail unless you compensate with wide bars- it's against fashion, but a slightly longer stem will give you more room to manoeuvre around the bike, as well as help with weight distribution.

456:

I'm from the old school of xc riding position and I can't get my head around this 'newer' riding style. It doesn't hold me back though

Hmmm…. That doesn't seem to have worked, the joys of the iPhone and flickr mobile!
Yeti: http://m.flickr.com/#/photos/66452821@N00/3543489998/sizes/l/

456: http://m.flickr.com/#/photos/66452821@N00/4744931751/sizes/l/

How does the saddle nose to top cap measurement compare between the two?

I take it from those pictures that you spend a lot of time in the saddle (as opposed to standing up)?

From memory, they measure similar (near identical)
I never lower my saddle

Bend your elbows down and kiss your stem for techy climbing with a short stem – once your used to the new position you'll wonder what the hell you where doing with that huge great thing you used to have.

Don't be tempted to move the saddle back or fit a layback post either – all these do is move the weight distribution further back and make it even more wheelytastic.

Either persevere and reap the benefits or stick you head back in the sand 🙂

Perhaps where you ride is not gnar(tm) enough to require this kind of equipment in which case perhaps an ordinary more XC setup is what you require?

Shorter stem makes front end "twitchier" and puts weight a bit further back on the bike. This is better for jumping and downhill stuff. For xc I'd ride 90mm plus, although I think on-ones are designed with a long TT so you can have a longer feel without compromising on the front end responsiveness.

I'm 6ft on a 18"

60mm stem

760mm 'flat' bars, were being run with the stem at -10deg and no spacers, felt great off road but a killer after 3 hours. Now at +10deg and 5mm spacer.

It feel's really short when sat down but perfect (almost a little long) stood up. Great for downhill hooning, but not so good on tight techy stuff and jumps.

So maybe I should get a layback seatpost on it, or even a 16", layback post and 80m stem?

Short stems and in-line posts.

Just a fad, to look rad! Don't be a fashion victim. 🙂

mine is shorter than my xc bike. but it is supposed to be.

got a 50mm stem and 710mm bars. used to run 70mm stem and 685mm bars which put me in a similar position.

The yeti is used for day rides, so the comment about being uncomfortable after a few hours is interesting. The 456 is more a 2nd bike, an alternative to the Yeti.
The stuff I ride varies from day rides, which I'd probably take the yeti over the 456, moorland singletrack, blasts around chopwell and thrunton. (thrunton is technical and steep)
I'm quite happy to just 'stick my head in the sand' and accept I need longer stems, just find it weird that this new style of geometry doesn't seem to work for me.

456 is hardly 'new' its just a beefed up inbred with 1deg steeper seat angle.

My Inbred which is very similar geometry is a 16" with a 70mm stem and inline seatpost.
I'm 5' 6" and did originally wonder whether I needed a longer stem. It definitely needed some wider bars, so I got those and now it seems pretty much sorted. I think I'd be stretching too far with a longer stem…

what width bar you running?

I'd have to check. From memory Easton ea70 low rise with an inch off either end. They were bars that were lyi g around in the garage

try some non cut down ea70 (about 685mm?) wider bars stretch you out a bit