Evening all, I have set up my spare MTB to commute on as one by nine using existing LX outer ring repositioned to middle ring and 9 speed XT rear cassette in 11-34 ratio with sram x5 shifter and rear derallieur. The front chainring doesnt appear worn and I set the chain up as normal ie round both big rings not through derallieur add two links to the length etc but I am continuosly dropping the chain off the front ring, doesnt matter what rear gear. Is it simply a case of getter a SS specific 42/44 tooth front ring (will the deeper teeth stop it) or do I need to go to the extent of putting a chain retention device on (seems a bit overkill for road work allbeit Coventrys monstrously pot holed roads).
I am reluctant to spend mega bucks and was even considering switching to a 29'er SS set up instead or revert it back to a SS with e less frustrating gear ratio than before 32×16 was way too low and added massive half hour to commute and made me look mental spinning at 1000rpm!

A SS specific ring may well be something of an answer. I think that a multi gear ring, especially if a Shimano/SRAM, may not be ideal because of shift gates in the teeth. Though I would have thought that you would find one combination that was stable. Otherwise a 1×9 chain device.

with an unramped chain ring I had virtually no issues with the chain dropping on my commuter nor does Mrs TJ on hers

Thanks for the replies, I had a search around and found someone doing the right size rings (although they seem reasonably rare). Any suggestions for suitable chain guides that are under the £30 it seems to cost for front ring (unless you know of a cheaper source for 42 tooth SS front ring TJ?)

nope – and I use a 36

http://www.chainreactioncycles.com/Models.aspx?ModelID=21874

Could be worth rotating it through 90 degrees to move the shift gates away from the point of least torque(when it's most likely to shift easily), i'd be interested to see if it does it with the ring fitted on backwards too.

If you have an old front mech just use this as a chain guide. Just adjust the stops so it sits over the single chain ring.

This is how I run my 1×9 set up, standard 44 tooth ramped outer ring in middle position

second the front mech option, just wind the adjuster screws in until it sits right

spokecycles, I thought that dmr thing was crap when I bought one. I used one of these instead, only 10 quid too..

N-Gear jump stop

http://www.billys.co.uk/english/group.php?prod=chng-js
http://n-gear.com/whatis.html

What was up with it? I've pondered one simply because it's a tenner less than the MRP/E13 options.

I used the full DMR guide and it was crap. May be because I was using it with a 32t ring so the top guide couldn't get low enough (think it's designed for 34t +). If you want to give it a go you can have it Suggsey, it's only going to get chucked out!

I've got my chaincage to work well on a 34 ring with a few spacers to get the positioning just right.

all you need is one of these.. costs 10 quid and weighs a few grammes.
simply bolts to the seat post and doesn't require any fiddly adjustment.

but what stops the chain bouncing over and outwards?

Tom- if Suggsey doesn't want it, I'd be interested, just to give it a go!

K.I.S.S. – just use an unramped chainring and it will be fine.

bashguard will also keep chain from slipping off the outside

like TJ i have been using an unramped ring:
http://www.sjscycles.co.uk/product-Thorn-Thorn-104-mm-PCD-4-Arm-Reversible-Single-Chainring-3-32-Inch–Black-11054.htm

Stills comes off once or twice a year, but puts up with clattering over steps and curbs on a regular basis.

I prefer this method as it is quieter and much easier to keep clean than using a chain device.

Superstar Components do one – 32 to 42 tooth single ring guide.

http://superstar.tibolts.co.uk/product_info.php?cPath=56&products_id=362