Transfer chain tension question
 

I need some help/wisdom on how to get the transfer chain tension to stay where I set it the first time. This occurs when I either 1. have to remove the chain to transport the tandem in travel cases, or 2. remove the chain to clean it. Every time I re-install and re-tension the chain to tolerance and torque the set screws, the chain either tightens or gets looser after an initial 20 mile ride. I re-adjust the tension, re-torque the set screws and try it again. I am torquing the set screws to the same tension each time. Sometimes, the second ride creates no change. maybe 25% of the time, I have to go through the process all over again. Then, the chain remains at perfect tension. I used PossumRoadkill's recommendation of centering the timing rings and that is definitely a help. This problem also occurred with my first tandem
So, do any of you have any suggestions as to what I am doing wrong and how to correct it?

When (year & month) was your tandem built?

Calfee. The frame was finished in July, 2008.

Just wanted to be sure it had the larger eccentric with the aluminum sleeve..., which it should: Yes?

http://www.thetandemlink.com/Images/...eccentric2.jpg

Are you using the stock Calfee eccentric (photos of older, smaller version and newer larger version below) or a Bushnell eccentric?

http://www.thetandemlink.com/Images/...entric_old.jpg

It does have the larger eccentric. Good question on the Calfee or the Bushnell. I don't know. I just looked at them and they look like the first thumbnail. They do not have the "smile" between the adjusting holes (middle thumbnail). Will find out tomorrow and let you know.
Thanks TG

The smile is on the inside so, unless you've pulled your bottom bracket or eccentric out of the frame you'd have never seen the "dark side" of the eccentric.

My knee-jerk reaction is to suggest you're not using enough torque on the two fixing bolts, as that was a big problem with our original eccentric. The larger eccentric was introduced in March '08 and the aluminum sleeve + large diameter + larger bolts was intended to solve the slippage problem vis-a-vis being able to use more torque and getting a better 'bite' between the aluminum eccentric halves and the aluminum sleeve. However, off hand I'm not sure what that torque spec is.

I've sent off a note to ask and will advise. Speaking of which, that would actually be my next recommendation.... Give Craig or James in service a call as they'd be in the best position to advise what works best for which ever type of bottom bracket you're using as well as any 'tricks'.

I covered a lot of our eccentric issues in Update #10 and Update #11 of my Calfee Journal under the heading of "Eccentricity".

Thanks TG. Craig or James should have the answer. I'll call them tomorrow.
I read through #10 and #11 and it sounds like a major case of heartburn to install a Bushnell.
Thanks again

For your frame, it's plug and play as the new Calfee eccentric shell is sized for the Bushnell.

Our frame was built with the smaller eccentric shell, hence the major surgery to bring it up to the current spec. We've had zero issues with our eccentric since having that eccentric re-worked and going to the Bushnell.

Of course, having the stock eccentric enlarged is definitely not a 'best practice' for owners of older Calfee's unless they're having a problem with their eccentric that can't be remedied any other way AND, even then, there would need to be enough 'meat' around the front bottom bracket area to allow for the larger opening. Again, James was quick to point out it was Craig who did the rework on our frame...

When I used that eccentric I used Tacx carbon paste between the eccentric parts and the shell. The adjustment never moved. In fact it was a bit hard to adjust it. I found that other eccentrics are easier to install bottom brackets and adjust.

Ditto... That was the solution I came up with as well. However, after a thousand miles or so our eccentric developed an incessant creak which ultimately led to the eccentric shell re-work.

That said, I would think the Tacx carbon paste or FSAs similar orange stuff would definitely make for a much more solid bond. However, before doing so with the new eccentric design, I'd want to get a reading from Calfee just to make sure I covered my bases.

To your point about "other eccentrics", that was my experience as well, hence the Bushnell we're now using.

http://www.thetandemlink.com/Images/...entric_new.jpg

TG- Steve Chang sent this e-mail
I think a bit more torque is all you need...At this time I don't have an exact torque spec., but will
get back to you on this soon, tomorrow.You definitely have the Calfee eccentric, which bottom bracket shell?, carbon or aluminum, I am not sure as we were changing over about the time your frame was built.
If your bottom bracket shell is aluminum then it is newer style. "Older" or "Newer" both work. The carbon paste can help. As soon as I get a torque number I'll let you know.

Will post his answer, probably tomorrow. BTW, my current torque value is 7.5Nm
VG

FWIW: The 'old' style without the aluminum sleeve is pretty easy to distinguish from the new and larger diameter eccentrics with the aluminum sleeve...

This is how the old carbon style looks, noting that there's nothing under the eccentric but the carbon frame whereas the 'new' style has that aluminum ring, ref the earlier photos.
(Click photo to see larger image)

http://www.thetandemlink.com/Images/.../calfee_b6.jpg


Off the cuff, that seems pretty low. I would think it should be closer to 9Nm - 10Nm... it will be interesting to see what Steve comes back with.

TG, I think I have the "new" style. I also never considered using 9-10Nm force. I always thought I would damage something internally that I couldn't see if I used that kind of force. Will let you know. BTW, just for grins, I just removed my transfer chain to clean it (not that it needed it after 100mi). I will wait to re-install after Steve gets back to me.
Thanks for the wisdom. You have "been there - done that".
VG

Finally got the answer. The fixing bolts need to be tightened to 14-17Nm. Tighten bolts evenly by alternating back and forth between the two bolts till you get to 14-17Nm each This torque setting along with the application of the carbon paste should solve the slipping issue. Hope this helps those out there that have chain tension problems
Cheers

They seem to be a bit busy this time of year. I tried to order some things and it's taking awhile to get them shipped. I guess the economy is not having much affect on their orders.