I have just purchased sliding dropouts for my commencal Absolut SX….

http://singletrackworld.com/wp-content/blogs.dir/1/files/2009/06/absolutsxdropouts1.jpg

Spot the obvious problem…….

The caliper mounts are fixed (not slotted like most designs)- so how am I supposed to align the calliper to the rotor when I tension the chain?

My thoughts are – you don’t, the wheel can only be located in the middle of the dropout.

This brings me nicely to the next point – why do sliding dropouts exist at all for this frame – and why have I just bought some?!!

That looks like a full suss frame. Unless the swing arm pivot is concentric with the bottom bracket the chain tension will vary as the suspension moves. This could lead to either a snapped chain or something much more expensive. Beware.

There probably is some margin for adjustment as the brake caliper will sit pretty much at the top of the disc, so a little movement back and fork will likely be OK, just double check that all of the pad is contacting the rotor. Less than ideal though.

Mostly Balanced

It is concentric

what Sam said – you’ll have a bit of fore and aft movement whilst the pads are still ok on the disk. I’d look at using a half link if you need to keep the hub pretty much in the right place, though.

Half link – good idea!

It is concentric

While you were typing that I was googling images to check.

similar set up on old dmr frames and the like, I always ran what ever size disc kept the caliper/pad parallel with the dropout and the half link sounds like a good idea too that way you only need 1/4 of an inch movement

Sounds like it can be made to work
Does jacking up the caliper a bit with shims help at all?
Do people suffer uneven pad wear if you cant get the whole of the pad on the rotor?

I’m just generally a bit miffed about the lack of thought gone into the design of this – accentuated by the horrific cost of the dropouts 🙁

….specialized look like they have managed it with there new design though….

http://www.pinkbike.com/news/Specialized-Debuts-Dual—Suspension-Slopestyle-Bike-at-Crankworx.html