Eccentric Bottom Bracket Modification

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Revision as of 23:45, 7 February 2007 by Pvd (talk | contribs) (One Possible Solution)
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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 285 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 or aluminum tube and use a Bushnell expanding eccentric.

A Bushnell EBB cam:
Bushnell ebb.gif

This will be researched a bit.

The PVD Mod

File:Rig1jpg

File:Rig2jpg

File:Rig3jpg

File:Rig4jpg

Rig5.jpg

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. 54 grams shaved off!

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