Difference between revisions of "Eccentric Bottom Bracket Modification"
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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 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. | + | The Fisher EBB measures 56.75mm (2.234"). |
| − | This is a picture of the Fisher EBB. It is designed like a giant quill stem. It weighs | + | 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.<br> |
[[Image:Rig wedge ebb.gif]]<br> | [[Image:Rig wedge ebb.gif]]<br> | ||
===One Possible Solution=== | ===One Possible Solution=== | ||
| − | It may be possible to shim the bb shell with some 0.050" delrin sheet and use a Bushnell expanding eccentric. | + | 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:<br> | A Bushnell EBB cam:<br> | ||
| Line 17: | Line 17: | ||
This will be researched a bit. | This will be researched a bit. | ||
| + | |||
| + | ===The PVD Mod=== | ||
| + | |||
| + | [[Image:Rig1.jpg]]<br><br> | ||
| + | |||
| + | [[Image:Rig2.jpg]]<br><br> | ||
| + | |||
| + | [[Image:Rig3.jpg]]<br><br> | ||
| + | |||
| + | [[Image:Rig4.jpg]]<br><br> | ||
| + | |||
| + | [[Image:Rig5.jpg]]<br><br> | ||
| + | |||
| + | 102 gram weight savings. | ||
===Other Peoples Work=== | ===Other Peoples Work=== | ||
| − | :*[http://www.creepyfriendly.typepad.com/ creepyfriendly] - 90 gram reduction | + | :*[http://www.creepyfriendly.typepad.com/ creepyfriendly] - 90 gram (unconfirmed) reduction |
:[[Image:Light2.jpg]] | :[[Image:Light2.jpg]] | ||
| − | :*[http://forums.mtbr.com/member.php?u=252893 mckeand13] - 80 gram reduction | + | :*[http://forums.mtbr.com/member.php?u=252893 mckeand13] - 80 gram (unconfirmed) reduction |
:[[Image:EBB1SMALL.JPG]] | :[[Image:EBB1SMALL.JPG]] | ||
| Line 46: | Line 60: | ||
===Final Weight=== | ===Final Weight=== | ||
| − | 135 grams. | + | 135 grams. 54 grams shaved off! |
I could probably pull off another 10 grams, but I've done enough for now.<br> | I could probably pull off another 10 grams, but I've done enough for now.<br> | ||
Latest revision as of 23:52, 7 February 2007
Contents
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 56.75mm (2.234").
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.
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:
This will be researched a bit.
The PVD Mod
102 gram weight savings.
Other Peoples Work
- creepyfriendly - 90 gram (unconfirmed) reduction
- mckeand13 - 80 gram (unconfirmed) reduction
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.
Making the Arbor
Machining the EBB
Final Weight
135 grams. 54 grams shaved off!
I could probably pull off another 10 grams, but I've done enough for now.
