Eccentric Bottom Bracket Modification

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Problem

I know a few people around the country that are sponsored by Gary Fisher to ride 29" Rig Singlespeeds for the 2007 season.

The biggest complaint that they all have is the weight of the stock EBB cam. I figured that I would make a tool to trim some fat off the EBBs for these racers. Every gram counts.

The Fisher EBB measures 56.5mm.

This is a picture of the Fisher EBB. It is designed like a giant quill stem. It weighs over 300 grams. That is some serious bullshit.
Rig wedge ebb.gif

One Possible Solution

It may be possible to shim the bb shell with some 0.050" delrin sheet and use a Bushnell expanding eccentric.

A Bushnell EBB cam:
Bushnell ebb.gif

This will be researched a bit.

Other Peoples Work

Light2.jpg
EBB1SMALL.JPG

Generic EBB Weigh In

This EBB cam is from a Zion Single. It's pretty generic and will serve as a good test peice untill I get the actual units in hand.

189 Grams.

Light-EBB-8.jpg

Making the Arbor

Light-EBB-1.jpg

Light-EBB-2.jpg

Light-EBB-3.jpg

Light-EBB-4.jpg

Machining the EBB

Light-EBB-5.jpg

Light-EBB-6.jpg

Final Weight

135 grams.

I could probably pull off another 10 grams, but I've done enough for now.
Light-EBB-7.jpg