Charlie says... Very clever mechanism that makes this the choice for Jeff Jones bikes and for many other when they replace their creaking rubbish EBB. Two wedges move away from each other, from the center outwards, causing the whole BB shell to expand.
It aint cheap, but nothing else works like this, What do you want, creak free chain adjustment, or £50 in your pocket and a cruddy BB that needs constant attention.
The Bushnell is a high-end eccentric lightweight bottom bracket shell for tandems or singlespeed frames.
- BB Shell = Inside Diameter 2.120 +/- .010 inches (53.848 +/- .25mm)
- Accepts standard 68mm English thread BB
- Replaces stock eccentric on old Salsa Juan Solo and old salsa El Mariachi frames, all Jeff Jones, cannondale bad boy, as well as many other frames.
- To be sure if it fits your bike, you need to measure the inner diameter of the BB shell on your frame. Then refer to measurements above, and if it is not campatible, order one of the shims that we also stock.
- Weight - 149 grams
- Width is 66mm (will fit bb shells up to 73mm width)
- Manufactured in the U.S.A.
"The Best just got Better!
The 2017 Bushnell® Featherweight Eccentric
Now designed to work even better with titanium bottom braket shells and other bottom bracket shells that use a relief through the center.
Bushnell Eccentric bottom bracket
Bushnell®, eccentric King
The Bushnell® Difference
Bushnell Eccentric Featherweight Wing
The original designdeflection animation
New Bushnell Eccentric Bottom Bracket Wing
The 2017 design
Why was this improvement needed?
As more and more companies began to build around the patented Bushnell® eccentric, some of them started to remove material from the inside of the shell in order to reduce machining time at the end of the build. This meant that the sides of the shell (about 8-10mm) were 54mm in diameter, but the inside of the shell was larger in diameter, and no longer contacted the eccentric when it was tightened up. In a shell that is consistent diameter throughout, welding distortion must be reamed out for any eccentric to fit and work properly. Titanium is very difficult to machine, especially after welding, so manufacturers started to relieve the inside of the shell before welding. Now they would only have to machine a small portion of the shell. This saves time at the end of the build, but there was a side effect that began to show up in the last few years.
Out of Contact
Since the inside of the shell was no longer contacting the full eccentric 'wing' section, it could 'deflect' (or bend) in the middle. Watch an animation of this. Something it could not do in a bicycle with the previous design, non-relieved shell as it made contact throughout the entire width. The new relieved shell allowed a mis-direction of the energy when tightening the bolt. Since some of the energy could go into the deflection of the wing sections, less energy is directed to the outside 'locking' circumference of the ebb. What this meant for the bicycle owner was 'more likely to have a creak'. The Bushnell® ebb is known for it's non-creakiness, so we couldn't let that stand!
Slow but steady occurrences
In the past, we might see one eccentric during a given year have a creaking issue that was hard to solve. That's one out of several thousand sold. In the recent few years however, it's been more like 3 or 4 (that might seem a small amount to most manufacturers, but we see it as a 300 ~ 400% increase and that's not acceptable to us). As these occurrences began to increase, it took a little bit of time to exactly determine the cause. While rare, it seemed to be with newer bicycle designs, and mostly with our titanium bike customers. Initially the sure fire cure was to send the customer a pair of 'Retro' wings. This always solved the issue, but added some weight. The Retro wings, are stiffer in this situation because they do not have any machining to lighten them up. As we began to analyze why the 'stiffer' wings solved the problem, the common factor was always a bicycle that used a relieved bottom bracket shell. Knowing that, it didn't take long to develop a fix. As is our policy, testing would be required before we made the fix public. We also like to use a controlled release of the product to allow it to prove itself before final adoption of the fix. Enter Budnitz Bicycles.
Method to our Madness
One of our big Ti bike customers for the Bushnell® ebb is Budnitz Bicycles. We have a close relationship with them because we built their frames for a while, and helped them with prototype development before they went to full production. They happen to use a bottom bracket shell of the previously mentioned 'relieved' style on all of their ti bikes and were experiencing some creaking issues in their newest bikes. They wanted to fix the issue, but didn't want to add weight to their bicycles. We love a challenge! and we went to work with some modifications to the Bushnell® featherweight for them to try. The version we came up with tested great in the shop, but the real test is in a bike...right? I showed them our new design, and sent out some samples for them to try. It was a success! They loved the results and ordered the new version for their 2016 line-up. We manufactured them exclusively for the Budnitz company for the 2016 season. This would give us a great control to prove the new design for titanium relieved shells.
The result? Not one reported issue with the new design for an entire year. A Huge Success!"