UTFS! ha ;P
There ain't that much out there but i've found the following: http://www.sheldonbrown.com/harris/schlumpf.html
(the pic on the left shows the one i have in mind, by that i mean the one i've seen just has a button either side of the crack arms. in other words, you don't have to shift the whole crack as shown in the pic on the right.)
UTFS! ha ;P
There ain't that much out there but i've found the following:
http://www.sheldonbrown.com/harris/schlumpf.html
(the pic on the left shows the one i have in mind, by that i mean the one i've seen just has a button either side of the crack arms. in other words, you don't have to shift the whole crack as shown in the pic on the right.)
On a similar note, i came across this beast:
http://www.mbaction.com/ME2/dirmod.asp?sid=&nm=&type=news&mod=News&mid=9A02E3B96F2A415ABC72CB5F516B4C10&tier=3&nid=0E0745C6A30C4BEF940905670D9D4B01