Cannondale lightweight compression top cap problems

Discuss light weight issues concerning road bikes & parts.
Posts: 166
Joined: Mon Apr 11, 2011 3:16 pm

by OwenJames


Took my rig down to the guys at my local shop. They are really decent mechanics there, rather than mere shop assistants, and seriously know what they are doing.

Well, they did the following...

-Took the whole front end apart, and inspected everything. Measured the roundness of the headtube top and bottom, and also the consistency of the shoulder angles. Did the same for the bearings. Everything fine there.
-Checked each part thoroughly. No problems there.
-Tested the bike with a few different stems, and different bars. With the different stems, but my same bars, the problem remained. With different stem and different bars, it seemed to go, although we are still not 100% on that. Didn't have a chance to take the bike on a 6 hour thrash through the mountains, whilst sat in the shop, obviously.
-Reassembled the stem with carbon paste. Bars with no carbon paste. Problem remained.
-Reassembled with carbon paste where stem clamps the bars... Problem seemed to be gone.

Now, I rode it home but did not hammer it in the drops. Before all of this shop work, I was getting the same clicking noise when giving it some force with my hands on the tops. Obviously in the drops applies more leverage so was more effective in making the problem occur, but I was able to get it happen sometimes when on the tops. I didn't replicate it on the tops on the way home.

So, it might be fixed. Only riding will tell, and I don't have enough time for a proper test today.

As an aside, this brings up an interesting topic of flex in the steerer / stem for me; When pushing hard on the bars, I managed to flex the steerer enough to cause things to shift slightly (bearings moving slight off centre, bearing cover shifting slightly). I realise that all materials have flex, but closely examining it revealed that it can often be a lot! No doubt this has been discussed to death already but I wonder how much flex is there by design, and how much is inherent of the materials / structure, yet undesirable...?

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