Despite a lot of negative reviews, I decided to buy a VK Saddle Adjuster, which pushes the saddle back 4cm from its original position.
On trying to secure the Saddle to the VK Adapter using the existing threaded (Upper) part of the Saddle Clamp, I found the supplied M8 50mm long bolt shoulder (unthreaded part of the bolt shaft) was far too long, and prevented the assembly being getting even close to being tightened as in the picture below:
Also I wonder if the supplied bolt as a whole might be too long, and could foul the underside of the saddle if it could be fully tightened.
Solution was to fit a shorter bolt (with a shorter shoulder), and the following picture shows the supplied bolt and the new shorter one:
The new shorter M8 40mm long bolt was found to be the correct length, and the following picture shows it correctly in place with just a bit of shoulder showing and sufficient remaining thread length:
The saddle is now firmly secured to the VK Adapter.
The next (and more serious) problem relates to the saddle centre being now roughly 4cm behind the original saddle clamp centre. No matter how tight the bolt is that passes through the Seat Post (a System EX I believe), the VK Adapter and Saddle tended to slip round on the Seat Post, causing the front nose of the saddle to raise up during a ride, and ending up making it very uncomfortable to sit on.
Examination of the various parts now making up the Seat Post clamping mechanism showed that there were smooth paint-to-paint mating surfaces which weren't gripping each other. Also the existing Curved Metal Clamp that is supposed to grip the metal under the Seat Post, was simply not up to the job.
The solution was first to remove all the paint between the metal-to-metal mating surfaces (Old Lower Saddle Clamp and top surfaces of the Seat Post), and to roughen them up to increase the friction between the various mating surfaces.
Secondly, the metal (aluminium) surface under the Seat Post which mates with the steel circular clamp, was filed to shape it to exactly the same profile as the Curved Clamp. Also any old indentations in the metal contact area of the Seat Post, which could cause the Curved Clamp to jump back into them, were smoothed off.
Despite this work, the VK Adapter and Saddle Assembly still tended to slip upwards - OK it was greatly reduced and only happened gradually during a long ride - but this continued to result in increased saddle discomfort and was still not satisfactory, as the saddle angle was going to have to be regularly reset.
I had to either further increase the friction / gripping action of the Seat Post Clamp Assembly, or to find a way of stopping the VK Adapter / Saddle Assembly from slipping on the Seat Post.
The solution I came up with is radical, and was only done after I was 110% sure the saddle angle was in the right position, as it can't be changed later.
Referring to the following picture:
I used Blue Pack Araldite Epoxy Resin to glue all the Seat Post mating surfaces, ie the Curved Metal Clamp to the Seat Post underside surface, and the Old Lower Saddle Clamp onto the top of the Seat Post - note the picture doesn't really show the glue on the surfaces.
Being one of the hardest epoxy adhesives I know of, it's never going to move again, but the big downside is that long term is it's never going to come apart either, which is why it's so important to ensure the saddle angle is correct!
Overall I feel the VK Saddle Adapter is a good idea and does go some way to solving Saddle fore and aft positioning, but it has a number of design flaws which could be solved with a bit more work, including supplying a bolt with no shoulder for instance!
Also my "bodge" with having to glue the parts is not good, and some better method of attaching the VK Adapter to the Seat Post is needed.
Also I'm aware that for some people the VK Adapter does work straight out of the box, but for many others it just doesn't and I hope this will go some way to helping them with some solutions.
