Photo evolution of modern eccentrics
Old School - 300 ~ 400 grams
(Your Grandfather's eccentric)
The old school eccentric uses a more or less solid block of aluminum with hardware welded onto the frame. Several bicycle brands still use this design today. In some cases, this type off eccentric can result in damage to your frame. Click here to see a photo of a damaged titanium frame that a customer sent us to see if the Bushnell eccentric might fix his problem.
Split/Wedge Design - 307 grams
(Your father's eccentric)
The split/wedge eccentric was developed in the late 1980's and is still commonly used in tandems today.
The first Bushnell Eccentric - 242 grams
(Your older brother's eccentric)
This design saved weight as well as replaced the 'wedge' with 'wings'. The wings were welded right onto the body. Adjustment became much, much easier.
Bushnell version 2 - 205 grams
(Your older brother's upgraded eccentric)
Same as version 1, but some holes drilled into the wings to reduce the weight of the piece.
Bushnell version 3 - 205 grams
(Your first eccentric)
In this version, Dennis added a spring to hold the assembly together. This way, it could be dis-assembled without having to break the welds holding the wings on. The screw was also redesigned and 'beefed' up quite a bit. Right and left hand threads now provided better reliability for the adjustment, and the part became even easier to use with no added weight. The action was reversed so the 'gripping' action was widened. This provided a tighter lock down for use in even more difficult applications (fixed gear bikes). Version 3 was a big leap forward!
The Feather Weight Bushnell Eccentric - 140 grams
(Your next eccentric)
That's a lot lighter than the piece started out. Now we remove unnecessary weight from all over the piece, and use 2 springs to hold the wings to the body. The part is annodized black, and the 'beefier' bolt is now stainless and hollow.
Still want more information!? Check out this article from R+E Cycles.