Bicycle Mechanics - 8, 9, 10 speed mix-and-match

So my current set up is a melting pot of different road components at different levels:

Sora 8 speed Shifters (Triple)
Tiagra Front Derailleur
Ultegra Rear Derailleur
7 speed cassette 12 - 28t with 4.0mm ghost spacer
8 speed chain
Truvativ Rouleur 10 speed Crankset 53/39t 172.5mm

and EVERYTHING works PERFECTLY Fine!:love:

Except there is a little chain rub when the front is on 39t and rear on 11t (no one should get that combination anyway).

Anyway I have spotted a great deal on some 10 speed Ultegra STI. I would like to ask you guys before getting in to any unnecessarily expensive experiment:

Is it possible to make the 10 speed shifters to work on a 7 speed cassette with 3 ghost spaces if I:
1. Pull out all spacers from a 10 speed cassette (3.95mm).
2. substitute my 7 speed spacers (5.0mm) with 3.95mm spacers.
3. Take up the extra spaces with aftermarket single speed spacers (they are cheap!)
4. Adjust the rear derailleur low limit screw.

I know this sound pretty extreme, but I already get a 7 speed cassette to work with a 8 speed shifter with 1 ghost space, why not 3 'ghost' gears? Theoretically the chainline will be straighter than before! :D

The limiting factors are:
1. Can the derailleur be set to a low limit that is THAT far (toward the HIGH) away from the wheel.
2. Are the thickness of 10 speed cogs the same as 8 speed cogs?

I just wanna know what you guys thing coz I dont wanna throw away my 7 speed cassette since it is still relatively new (less than 2500 miles):giver:

http://www.sheldonbrown.com/k7.html#spacing

Problem is the cogs on a 10sp cassette are thinner as well as the spacers, so subbing spacers from a 10sp cassette into a 7sp cassette will not get you 10sp spacing.

Cog spacing on 7sp and 8sp are nearly the same, so that's why that works for you.

My 8 speed actually uses 7 speed cogs with thinned spacers.
I had two 7 speed cassettes and picked up an 8/9 speed FH body for too cheap not to, so I thought why not?

Basically, you just have to have the center to center spacing of the cogs correct for the speed of the shifters and a chain narrow enough to fit between them without rubbing.

Everything all went wrong when companies decided to go to 9/10/11 speeds. Thinned cogs, chains, and sometimes chainrings, makes interchangeability with 8 and older problematic. No more simple compatible swaps with other bikes and equipment in your inventory.
IMHO, for the average recreation cyclist, going to 9+ is simply flushing money down the drain.
But we live in a consumerism society where having the latest and greatest boosts one's self-esteem.

As long as you properly choose where you want those "ghost gears," thus adjusting for good chainline, my instinct says that it should work. However, my instinct has proven me wrong before....:thumb:

Yeah, give it a try. Fiddle with it.

Don't throw away the old cassette. Put it back on if the experiment doesn't work out.