Cannondate Eccentric BB will not move!
 

Hi,

I'm having absolutely no luck getting the eccentric bottom bracket to move on my Cannondale (it's a 2006 Cannondate Vintage, very similar to the Cannondale Bad Boy bikes). Many of the bikeforums posts relate to the eccentric bottom brackets for Tandems, and I think the eccentric I have could be different. I've also read the 'Cannondale Maintenance Instructions' thread, but that hasn't helped. I've taken a couple of pictures of the BB here:

Right-side:
http://emu.appspot.com/upload/right-side.jpg

Left-side:
http://emu.appspot.com/upload/left-side.jpg

The wedge itself loosens OK. The problem is that the BB simply will not rotate. I have tried rotating the BB using the SPA-4 Park Tool, which has resulted in some slight damage as you can see on the second image. I'm wondering if I need the SPA-1 tool instead? I'm thinking about putting an allen key or screwdriver into the top hole on the right-side, which goes right the way through, but am concerned about damaging the BB. I've also tried spraying the seams with WD40.

If anyone can suggest a fix?

Thanks!

you may have to put the bb back together, and use the axle to move the bb. or you will have to remove the bb and clean it out and use the blue loctie when you put it back together. don't know if cannondale did in the buildup of this bike. (clean out the bb or use any kind of lube or locktie.) use ammonia instead of wd40, we are talking about a aluminum frame here.

i haven't worked with EBBs before but from what I read, there are supposed to be pins holding in the EBB to keep them from rotating. It looks like there's some silver pins in the holes in your EBB. Are you able to get those out ?

Thanks for your comments.

Bikeman715, I put the BB back together, but still cannot get it to move... I wish I could remove it to give it a good clean, but it seems set like concrete. The last time the chain was tensioned using the BB was at a bike shop, so I don't know what lubrication they used (if anything) with the BB.

Atchen - thanks for the pointer. I looked in each of the holes for a pin but didn't find anything. The two small circles in the middle hole on the bottom image are connected to a washer which I think prevents the screw from backing out of the hole when the wedge is loosened.

Looks like I'll have to take it to a bike shop. So frustrating!

Cannondale tandems are somewhat unique in that they use a wedge-style eccentric instead of a pinch-bolt style. Looking at the second photo, there's a circlip behind the hex bolt which is probably designed to loosen the wedge if you back off the bolt far enough. It's the same principle as "self-extracting" crankarm bolts.

Here's an old thread with links to a variety of maintenance documents addressing this issue:
http://www.bikeforums.net/archive/in.../t-287800.html

Thanks Jeff, I'll try removing the circlip tomorrow and then backing the bolt out. Hopefully that should loosen the wedge enough to enable the BB to move - will report back.

You got it wrong- leave the circlip in there and unscrew the bolt until it pops the wedge loose. Like I said, this works in the same fashion as self-extracting crank bolts.

Ah... OK. The wedge actually loosens no problem. The issue I'm having is getting the BB to rotate.

Urck! Now I get your problem.

If I were working on the bike, I'd remove the bottom bracket cups and the wedge pieces and then start tapping the eccentric sideways to see if it'll loosen that way. It's probably been in place long enough to develop a little corrosion between the eccentric and the shell. One it's unstuck, clean off the outside of the eccectric and the inside of the shell, then reinstall with plenty of grease.

A quick update. Eventually I gave in, and took the bike to my local bike shop who did a great job of removing and cleaning up the EBB. I had a chat with the mechanic afterwards who said that the EBB had been put in the wrong way around (which he sorted). Also that the EBB consists of two wedges, and the trick, once one wedge has been loosened, is to give the wedge bolt a tap, on threaded side, to loosen the other wedge. That was the trick I was missing. After that he said the EBB rotated freely.

Thanks all for you suggestions, great forum!

Sorry to bump an old thread, I have exactly the same, the wedge on the non drive side is loose, but the drive side wedge is solid and the whole thing is stuck fast in the BB shell. I don't want to take it to a LBS just yet as I want to do it myself.

I have tried a few whacks with a rubber mallet, nothing.

Any tips at all to free this? It is really annoying me now.

I'll try anything.

try using something like PB Baster (get at any hardware store.) in there. if it doesn't work try ammonia ,you may use a heavier hammer to hit it a little more to break loose the wedge . may sure you hit the head of the bolt.