Just built a Dialled Alpine Mk2 out of the bits off a Prince Albert. Rides lovely.

The rear mech is an old (well I've had it 5 years and it was used before that) and I've noticed that the chain doesn't have a lot of tension – it slaps the stay very easily. It prob did this on the PA too – but I didn't hammer it very hard. Is there a way of tightening it up? – I cant make the chain any shorter – i dont think – the mech cage is already pulled forward a fair bit.

Would a newer mech be (thinking of the SLX medium cage) keep everything a little tighter?

Should've mentioned, the rear mech is an XT – long cage (i think)

Get a shortcage mech.

Also, what size is the largest cog at the back? If its a 32, you may even be able to use an old road mech like a shimano tiagra/105. If its 34 i doubt it will work

Thanks.

It is a 34t – but I can swap that out.

Will a 105 10 speed rear mech work with an mtb 9 sp shifter? I'm guessing no –
http://www.chainreactioncycles.com/Models.aspx?ModelID=28072

Isn't it the shifter that's indexed rather than the deraileur?

Medium cage XT on mine here.
No real issues.
Old tube chainstay protector probably doing a good job though when i think about it.

I have a short cage rear mech on my 9spd Prince Albert – see here:

I also have an innertube chainstay protector , but I'm pretty sure the chain is too tight to slap about onto it most of the time.

Ta – I'm running a short cage X0 on a dialled holeshot with no issues – just cant stretch to one of those at the moment for the alpine –

there's very little choice for short cage shimano rear mech's 🙁

You should be able to get the chain tight enough with a long-cage mech.

Your rear mech looks quite far back compared to my 1×9 (also using a long cage mech). Mine goes near-horizontal in the largest sprocket, and the chain is as taught as Jordans bra-straps.

Take the chain out of the rear mech and wrap around the largest sprocket on the back. Measure out an extra two whole links (or three if you are nervy) and trim the chain to this length.

Poppa – cheers – so do a complete wrap of drivetrain – lowest gear on block through device and round front ring – add two links and chop?

EDIT – but NOT through mech yes?

I cant be that far off that….in the 12t cog the cgae hangs at about halfway between a 4 and a 5 on a clockface – if you get me