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Re: Cannondale Eccentric Bottom Bracket Removal

Andy Hyde2005-04-01 13:53:57

: There are two main ways I know.

: 1) Undo the M5 bolt (the one between the two holes) a little bit (3mm?) then
: hit it (hammer+punch?) to release the wedge. Then undo completely, pushing
: the wedge out as you go, if you want to remove rather than just adjust.

: 2) Take the M5 bolt out completely, then put another one in from the other
: side, with a big washer, such that the washer holds aganst the frame and
: lets the bolt pull the wedge out. I do this with the same bolt, and a nut
: to push against the washer (ie my extraction kit consists of a washer and
: a nut and an 4mm allen key)

: To adjust, it doesn't need removing. Some people use pin spanners to turn
: them, I use an allen key in one of the holes, and push one of the cranks
: against it to turn the entire thing.

: Have a look at the tandem@hobbes archives for discussion on this too.

: cheers,
: clive

I've done the same thing (using an allen key) and was able to adjust my timing chain quite easily. I think the key is to make sure the eccentric moves easily in the bottom bracket.

Alex Reeves2017-05-22 18:56:29

Just found this post, as we have a Cannondale tandem in the Charlotte's Tandems fleet. I had originally tried method one, before I saw this post, and it didn't work. I then tried you method two, which was so easy and worked well. Thank you.

Best wishes, Alex of

Charles Kendall2017-06-15 14:44:51

I have a Cannondale Mountain Bike style tandem probably manufactured around 2010. It had lain around in the cycle shop for a few years before we bought it at a good discount. Now for the first time I needed to adjust the tension of the timing chain by rotating the eccentric bottom bracket. It is actually the best looking bottom bracket I have seen and looked exactly as described in a very nice document on the internet entitled:
However the removal instructions did not work at all
I consulted a local large cycle shop who had no useful advice apart from telling me to rotate the eccentric - why didn't I think of that!
Finally in desperation I explored a bit more and found that it was in fact a double wedge which when I truned the locking screw more and more first the far side then the near side wedge was pushed free. Problem solved.
Of course afterwards I found the following document on the web which exactly describes my double-wedge setup: