Shift Kit Chain Tension Issue

I'm afraid part of the problem is that the shiftkit you purchased is simply a copy of a now (very) outdated design - later editions included an upgraded rear backing plate with a vertical support & tensioning bolt (threaded rod actually lol). While this still entailed periodic adjustment to account for chain stretch - at least it solved the mount movement issue. Check http://www.sickbikeparts.com/Manuals/SBP2 Manual001 Rev A.pdf to see what I'm referring too - while it's the installation instructions for the newest design it still incorporates this vertical support.

Another thing you can try is what I did to help prevent kinking the tubing with the U bolts;



I just took a chunk of pipe with the same ID as my seat post tube's OD, cut it in half and ground a taper to fit it in the U bolt - then tack welded the steel "pads" to the U bolts (don't hafta do that, but it helps during assembly). Don't try this with any sort of soft padding as it'll make the movement far worse. Roughing up the inside of the "pad's" surface should give you enough grip w/o having to tighten it so much as to crush the seatpost...

...but I think you may wish to replicate the threaded rod vertical support that the SBP kit has had for quite a while now - a couple of chunks of angle steel, threaded rod, a few nuts & another U bolt clamp would be all ya need


As for the chain stretch - if you pick up a quality, heavy duty BMX chain, it'll still stretch a bit as it breaks in and fits to the sprockets, but after a while it'll settle down and you'll not hafta mess w/it nearly as often

I have that whole threaded motor assembly kit support parts I didn't need.
You can have it, just pay the shipping.
As barley mentioned, it is just a U bracket, some angle pices and a long rod with threads on each end with nuts.

The new Sick Bikes jackshaft has a 1 piece U shaped back plate so there should be no issues with one side plate moving now.

Can't wait to try one.