Tandem Cycling - Tight (Calfee) Eccentric

Just changed timing chain and realized why I was never able to adjust our eccentric. Took a hammer and screwdriver to get the thing out. Some oxidation/corrosion on the eccentric, and I guess the shell is carbon (late '07 frame). Cleaned it up, put it back together, considered lubrication, opted against, timing chain is very tight, and I still can't budge the eccentric.

1) How snugly should this type of eccentric fit?

2) How do you apply leverage to get it to tighten/loosen the chain?

1) How snugly should this type of eccentric fit?

2) How do you apply leverage to get it to tighten/loosen the chain?




1. What does your eccentric look like? Calfee gives torque specifications for their eccentrics. Use carbon assembly paste as a lubricant. Did you damage the BB area with the hammer and screwdriver?

2. With a spanner tool.
http://www.parktool.com/products/detail.asp?cat=25&item=SPA-1

Hmmm. Do you sweat a lot when you ride? Regardless, welcome to galvanic corrosion

1) How snugly should this type of eccentric fit?

Not all that tight, to the point where when loosened you should be able to rotate it by hand. It's the pinching action of the two bolts that pull the two halves of the Calfee aluminum eccentric into the carbon eccentric shell and it's that compression force that keeps the eccentric from moving, at least in theory. Frankly, a lot of Calfee owners (including us) had problems with the darn thing being too lose and rotating / loosening under load.

2) How do you apply leverage to get it to tighten/loosen the chain?

As previously noted, I rotated mine by hand. The trick for me was getting the eccentric to NOT rotate when I torqued the two bolts that held the thing in place, and that necessitated putting the bottom bracket cup wrench when I tightened the eccentric.

Did the corrosion mar the eccentric's smooth outer mating surfaces and/or do the same to the eccentric shell? These two surfaces need to be smooth to allow the eccentric to rotate. If they're not, that's either THE problem or part of the problem. It's also possible that your eccentric halves or even the eccentric's inner surface became slightly deformed when you banged the eccentric out of the frame: that would be a problem too.

My recommendation would be to take a couple photos of your eccentric shell (without the eccentric installed) as well as the eccentric halves sitting out on a table and send those photos along with a note to the folks at Calfee with a request for their assessment. My guess is, you may need a new set of eccentric halves. If you do need a new eccentric, I'd play the warranty card for the eccentric on the corrosion issue in that I don't believe there's any instructions that come with the frame to suggest that some type of assembly paste or corrosion inhibitor be used to prevent what you had happen. Anodizing is not, in and of itself, sufficient to prevent galvanic corrosion... it just slows it down a bit.

As mentioned in our Journal, we eventually had our eccentric reworked to the new standard to eliminate all of our problems with the eccentric being loose and creaking.... and with any potential galvanic corrosion problems.

+1 on TG. Our Calfee is a year old, not quite as old as yours. I sweat a lot too. So, when I tore the eccentric down about four months ago to replace the standard bearings with ceramic, I had to clean out a lot of corrosion before I re-installed the eccentric and bearings. I re-installed with TACX assembly paste. Calfee also recommends torque values on the two retaining bolts to be 14-17Nm. I originally had them much too loose.
The eccentric generally doesn't move, although we are now at Lake Tahoe and doing a lot of climbing. The eccentric rotated, and thus tightened the chain a bit, but was still smooth when I loosened the bolts to put more slack in the chain. I suspect there is very little (if any) corrosion penetrating through the TACX.
Hope this helps.