No matter where one comes down on the different theories, we know of one place where both exist. R+E Cycles....of course.

When we joined forces with Dennis Bushnell, one of the thing that we inherited (along with Dennis, Jenny and Toby) was the Bushnell eccentric business. Now, you may think that we've always been a little bit eccentric, and you would be correct, but this is a little different. In the tandem world, the eccentric is one of those components that lives on a tandem, and when functioning properly, pretty much goes un-noticed. It's the part of the tandem frame that the captain's bottom bracket (where the crank arms mount) is installed. As the timing chain (the chain that connects the captain and stoker cranks together) stretches, the eccentric allows the captain's bottom bracket to be moved forward to tighten the chain back up. It's a very necessary peice of equipment on a tandem, and now the single-speed or fixed-gear bike manufacturers have discovered this slick item for their purposes.

Up to our knees:
Dennis has pioneered the developement of the eccentric that we use in our Rodriguez tandems, and have for years now. I've always thought is was a fantastic product. When Dennis and Jenny were preparing to move their shop up to Seattle last November, Jenny called me and told me that they had orders in for 100 of the Bushnell ecentrics. She said that they could cut up the material for the 100 pieces and then we could machine them after the move. I suggested that they cut up the material for 400 eccentrics (100 is the biggest single run that they had done in the past). Well, after the move, we spent some time designing and making some new tooling to speed up production, and then Todd, Jenny and myself spent the entire month of January up to our knees in aluminum shavings making 400 Bushnell eccentrics. After that batch of 400 was done, I had a whole new respect for this quality component, and the design work that has gone into it. From January 1, 2005 we have sold nearly 900 Bushenll eccentrics.

The difference between eccentrics is hard to see from just looking at a tandem, so I thought that I would write this article and describe the different evolutions that they have gone through.

Evolution and intelligent design:

Your Great Grandfather's eccentric (prehistoric):
Before the eccentric, tandem manufacturers used an adjutable pully wheel to take up the chain slack as the chain stretched.

Then someone (I don't know who) came up with the idea of moving the front crank forward in the frame to adjust for chain stretch. This idea looked a lot better than the old and caught on with most tandem manufacturers.

Your Grandfather's eccentric (he's really just pretending....to fool Grandma):
The early eccentrics were made from a chunk of alluminum held in place by pinch bolts on the frame. The pinch bolts could be loosened, and the chunk of aluminum could be rotated to tighten the chain. It worked pretty well, and looked a lot better than the old way.

Another type uses sharpened screws to dig into the aluminum chunk when tightened (instead of the pinch bolts).

A lot of tandem manufacturers still use these types of eccentrics.

The draw back to these types of eccentrics is that sometimes the threads on the frame will strip out, or the threaded piece may even break off of the frame. This requires a costly frame repair and paint work. The sharpened bolt style also has a gouging effect on the alluminum chunk (kind of crude we always thought).

Your Father's eccentric:
In the late 1980's a company (we'll call them Large-Gun dale) came up with a design that didn't use threads on the frame, but in the eccentric itself. We're not snobs, and we recognize good design when we see it, so we switched. It used a wedge that could be tightened by a nut/bolt system. If the threads got stripped, it was just a small repair instead of a costly frame repair.

The drawback to this system was in trying to loosen it. To loosen this system properly, it required a long punch and a hammer (when someone is coming at your expensive tandem with a hammer, it's kind of scary). One had to loosen the bolt and then hit the large peice with the hammer and punch until it broke loose int he frame.

The other problem that we ran in to was that non-tandem shops would loosen the bolt, and then hit the bolt head with a hammer. This would drive the threads right out of the special nut. Then we would have to red label one of the special nuts to Timbuk Tu.

The modern eccentric:
Well, a few years after that, the Bushnell design was born. Dennis came up with an ingenious design that used the bolt in the eccentric to both tighten and loosen the aluminum chunk in the frame. The need for the hammer and puch was gone. The Bushnell eccentric looked great in the bike, and was the easiest design to adjust as well. Like I said, we recognize good design when we see it, and we switched immediatly.

Dennis then went to work improving and lightening up the design to make not only the most evolved eccentric on the market, but also the lightest and best looking.

It has now become a sought after component for manufacturers of some of the highest quality tandems and single speed bikes on the market. You didn't think that we sold 900 tandems since January did you?

Function over flash:
Well, the Bushnell eccentric has gone through several evolutions to get where it is today, but is by far the best designed little piece on your Rodriguez tandem that you'll never notice.

Our choice of eccentrics over the years is just one ways that we focus on putting the best performing product on our bicycles, not just the most 'magazine-hyped' products. The Bushnell eccentric is much more expensive than an aluminum chunk, but it serves the bicycle owner much better.

After my experience in January, I have a new found respect for the development and manufacturing process of this incredible component, and I hope that you will too.