Does anyone one make odd rings to fit a regular XT chainset.I remember seeing Julian Absolan's bike with a Noir crank (before he moved to XX) with a 40 tooth outer ring and a 30 tooth inner.Seems like a good combo! Specially made maybe?
Thanx Max

Try specialities TA rings – they are made in a bunch of sizes and I think you might get the ones you want – although its a ridiculously high gearing IMO

Yep, TA Chinook.

The 40t is nominally a middle ring, so it has more shifting ramps etc, but works fine. Extralite do a 30t 'middle' ring, but you have to file your spider to get it to fit properly. Much better is just to use a TA inner ring in the appropriate size. I ran 28/40 for most of last year and found it really good.

30 is reasonably tall as a bottom gear, I'd suggest a 28 would shift better and be more versatile.

Better chainline when running the two rings in inner/middle position too, and I found I could use the 40t ring for the majority of my riding.

BETD used to do odd sized rings I think, Blackspire rings sometimes come in some strange sizes, Middleburn maybe? The main trouble is I don’t think you can fit a ring smaller than 32t ring on a 104mm BCD so you’d be after a 30t Granny mounting (64mm) ring, not so common, the other option might be 28/40 or 28/38 both of which I reckon you could get hold of then look at changing the Cassette range to suit, if anything smaller chain rings means you’d need a closer range and thus lighter Cassette perhaps obviously your highest gear 11-40t has to be one you think you’ll use, otherwise a 38/28 or 38/26 setup makes more sense as it gives you the option of marginally spinier gears for rally graunchy climbing should you require and more easily sourced chain rings…

The other thing to consider is what front mech will you be pinging the chain back an fourth with? SLX double is a good option as it can accommodate a 14t difference in rings, but claims 36t is it upper limit (that would of course assume a 22t granny I reckon you could do a 26/38 or maybe 26/40 with one, the point is you’re current mech might not accommodate the big step you’re considering…

Why do people not read previous replies? As I said, Extralite are the only company to make a 30t 'middle' ring, but you have to file the spider. There's no advantage to using the big/middle rings, the chain line is better with middle/inner. It's also quite expensive and they don't last particularly long.

You can use whatever front mech you want, I've used XTR and Dura Ace both to good effect, no need to have the double specific MTB one at all. Actually the 10t gap you're proposing isn't a problem in the least, it's smaller than a normal big-middle jump.

TA do 26/28/30t inner rings, see here: http://www.specialites-ta.com/produits/plateaux/tableau-2008-VTT.pdf

have a look at Dotbike and SJSCycles websites

Why do people not read previous replies?

Too busy writing my own post to read the other preceding pedants….

While a 30/40 is only a 10t jump not different to a std chainset, once you get into 40/28 or 40/26 (which are more easily achieved combinations) or bigger than 10t steps then not all mechs accommodate, I’ve run 38/26 myself in the past and found the XT I used didn’t quite have the range so 40/28 would have a similar issue…

The whole point of the SLX double is that it allows a more significant difference between the 2 rings giving an overall broader spread of gears…. Odds are the OP will more likely wind up having to deal with a 12t difference in chain rings which his current mech may not cover.

I’m simply presenting a possible option or two, nothing I say is gospel, or indeed 100% what the OP was driving at, such is the nature of the interweb…
Apologies if I offended…

I’ve run 38/26 myself in the past and found the XT I used didn’t quite have the range so 40/28 would have a similar issue…

That's a 12t jump, as is 32-44, why would it not work? I've had no problems running standard MTB mechs on 28/40. 12t is not a big jump for a standard mech to cope with! A huge number of XC racers have been running doubles for years, and they still changed gear before SLX came along…

Some chap on Weight Weenies was running a 22/40 or something with an MTB front mech.

Not offended in the least, and didn't meant to sound quite as facaecious as I did, and probably do in this post either, but hey!

Thanx for the help guys.Have currently been running my XT with no granny so its 44/32! Which is fine as its a XC bike.Just want a bit more scope for lower gears.Lked the 40/30 jump as theres not much difference between rings and shifting should be good.Really like the doubles as you use all the gears but looking at options as had a bad experience with a Middleburn Duo(poor shifting!).
Thanx Max