Can I swap a rear 160mm rotor for a 140mm on my Boardman?

[chucklight]

I've done a few more small jobs which drop the weight a little more, I'll update shortly.
Those jobs got me thinking though...

I usually ride on road, singletrack and general X-country so I rarley heat up my 160mm rear rotor which makes me think that a 140mm rotor would be totally fine.

So is it possible? Would I need to downsize my caliper, shift the caliper rearwards by removing spacers, change pads?
I've uploaded a pic so you can take a close look, I've no idea so any help would be much appreciated.

[url][url=http://www.flickr.com/photos/79798036@N02/8184700949/][/url]
DSC09774 by Chuck-light, on Flickr[/url]

[url][url=http://www.flickr.com/photos/79798036@N02/8184741126/][/url]
DSC09776 by Chuck-light, on Flickr[/url]

(excuse the muck, only just got in)

Cheers guys

[TheRookie]

It's not happening, you have a post mount frame mount and it is set to make it suite a 160mm disc with no adaptor, so 160mm disc it is.

[02GF74]

^^^^ nope as he said - not unless you modify the frame.

[UpFromOne]

if you elect to trim down the post mounts, by 5mm, and do not use washers between the caliper and the post, you can drop the caliper by 10mm total, allowing for a 140 rotor.

The downside is not that there wouldn't be enough threading in the post (they are tapped quite deep enough), but once you trim the post, you'd need a 160-to-180 post spacer (10mm) just to go back to a 160 rotor w/ std. washers.
Not to mention losing a bit of caliper adjustability with no conical washers.

I have done this with noissues whatsoever, but never trimmed the post by a full 10mm just to save the caliper washers.

[TheRookie]

Those posts won't trim by 10mm, yes you could trim by 5mm and lose the washers, but then you'd be stuck with Avid callipers forever....

[bobbyOCR]

Just don't do it. I'm all for tuning, but this isn't happening.

The weight saved, for once, will not be worth the list of negatives as a result.

[TheRookie]

Too right, the thought of never being able to junk the Avid brakes is terrible!