I know this keeps cropping up on here but I really dont want to be in the position of buying stuff and sending back its a real ball ache. So… I have a FSA V Drive standard crank that I wish to convert to a double and play around with, its this one:
http://www.bikeradar.com/gear/category/components/cranksets/product/v-drive-megaexo-09-33325

And I am looking to remove the outer and middle rings keep the inner and add this ring on :
http://www.chainreactioncycles.com/Models.aspx?ModelID=35780

Along with this bash:
http://www.chainreactioncycles.com/Models.aspx?ModelID=35781

And a Blackspire Stinger to keep chain tension up.

Will this setup work? I am a bit concerned as the chainring is listed as an outer, I guess it will have a pin on it to stop chain going inbetween crank and ring – will this screw things up for bashguard? Not sure if you can use outer rings as middle. Also worth mentioning I have a med cage rear mech.

Which size of the ones you link do you mean? If it's the 36 (which is what I'd suggest) then it should be fine and since it'll be in the middle ring position anyway, the lack of stop will not be an issue.

Why fit a bash guard though? I know people do for fashion reasons but do you really need one?

You also don't need a tensioner (eg the stinger) – you just shorten the chain to match the new biggest ring.

It is worth considering a double specific front mech though.

I don't think you can use an outer as a middle (could be wrong though)but if the BCD is the same you should be able to use a shimano or race face etc. middle. Also if your just trail riding and still using a rear mech then you shouldn't need a chain device.

You can use an outer as a middle but if you're going to have a 22 and then a 44 (eg normalish outer size) then the jump in size is going to cause problems.

Cheers, I am looking at the 36, one of main reasons for doing this is to get rid of chain slap and would be great to have a more simple setup. At the moment I just don't get out of middle ring then when I do use my outer I forget and in the heat of the moment slip into big big need to aviod this.
I dont think I can get a dbl front mech as it is a direct attach, I think they only make them in 3 speed so Im guessing will have to shorten cable and play with limit screws.
I looked at the bash to keep things neat and figured it would prevent chain coming off outer ring. The chain device I thought would help with chain slap and keep everything tight.

A chain device will stop chain slap but will look completely overkill unless you are on a 6"-7" + downhill bike. Just make sure you are on big front and one of the biggest at the back to reduce slap.

Obviously shorten your chain. No need to shorten the mech cable – just get the stop in the right place

do you get height adjustment with a direct attachment mount?

36T set ups work best if you move the mech up (normally up the seatpost) from a 32T position.

I have gone for the chainring and bashguard, I have taken teeth off before so would be good to have protection. I will leave the chain device for now and see how tightly I can get this set up. With a med cage rear mech Im hoping I can get a tight chainline, I may look to change the inner ring to a 24 or 26 as I find granny gear ueless even here in deepest darkest Wales.

@ thomthumb

You get a little about 10mm on a slider on the mech, I may run into problems with the front mech but have seen other with doubles so must be a way 🙂

From my experience, you won't have any probs with the front mech. I've removed the big ring before and just left the mech insitu, it worked fine, but looked a bit silly.