I have an issue with the headset on my 2014 SuperSixEvo, and I wondered if any of you had the same issue / had any ideas?
When heavy braking on the front brake, the headset seems to move somewhere (haven't started micro-analyzing it yet). I can feel it kind of click forward, at the end of the braking stage (when I am coming to a stand still, or have hugely reduced my speed over a short distance). Then, when I steer left or right, the headset make a kind of scrawking, plasticky rubbing noise. If I then keep on riding, the noise goes away, until the next time I brake heavily. Under 'normal' braking this does not happen, and the headset has no play in it at all when the bike is at a standstill, or even when I apply the brakes whilst riding along normally, and put my fingers round the headset to check. This only happens under heavy front braking.
Stuff I have checked;
I have taken the whole front of the bike apart, of course, and done the following;
-Checked for cracks at the top and bottom of the headtube, and the angled bearing seats. Could not see any cracks. There was evidence of slight movement of the bearing against the carbon bearing seats in the headtube, by way of a slightly shinier, rubbed area where I assume the bearing race contacts the carbon, but this was not an area which had any gouging, or material removed, just kind of polished a bit through rubbing.
-Checked the bearings for cracks. Nothing. I know it is not possible to check how the bearings respond under load when they are in your hands, but they felt smooth and there was no corrosion or visible damage. Again, like the bearing seats, there was a slight indication of rubbing, but only through slight polishing, and no gouging.
-Checked stem bolt tension, compression wedge tension, etc. All fine. Nothing moves when I spring, and indeed, no sound happens when I sprint; this is only when I heavy brake on the front.
SuperSixEvo, 52cm, with Deda Superleggero stem and bars. 10mm spacer under stem, 5mm spacer above. Cannondale superlight compression wedge. I had this exact set up on a 2012 SuperSixEvo, without issue.
So, given this evidence so far...
Any ideas / thoughts?
I've found that hidden type headsets require a tighter compression adjustment than external headsets.
I check mine by dropping the front of the bike a few inches and listening for a rattle. It's hard to describe but when you have done it on a known to be loose headset then you'll know the sound. When adjusting I tighten the compression adjustment until there is a slight drag on the steering, tested by holding the bike up and letting the bars flop to one side.
The bearings are the ones that came with the frame.
The headset is not loose under anything other than heavy braking, so there is no rattle; and yeah, I am extremely familiar with that sound - rode BMX for 10 years and MTB before that, in the mid-90s, during the early days of AHeadSet adoption, so there have been dodgy headsets aplenty!
Your idea that something is preventing the headset from being fully tensioned... could you list the possibilities that you can think of, so I can see if I have checked them all. The main one, was to ensure that there was enough gap between the top of the steerer, and the top of the spacer on the top of the stem, so that the compression cap was not topping out when tightened... That all seems fine though.
The other thing I had thought it might be, was some kind of stem slipping.
When you brake really hard, the fork dropouts try to force themselves back under the frame (excuse this loose engineering talk; you know what I mean by this), which in turn means the bottom of the steerer is forced to the back of the bottom of the headtube (the top of the steerer is forced to the front). This movement is not allowed to happen if the stem holds in place, as by remaining in the same place, the stem maintains the effective length of the steerer tube between the bottom race and itself. If the stem slips, however, then the effective steerer tube length is allowed to increase (effectively unloading the system a bit) and this movement is allowed. If this is what is happening, then I can see why that would only occur, perhaps, under heavy braking, as it would need a fair amount of force to make a stem slip like that. This is all theory though, so could be bollocks.
Again, any ideas or thoughts would be very welcome!
1) Is the headset cap (not top cap, below stem and spacers) touching the top tube? There needs to be a small gap otherwise the stem binds on the frame not on the headset and prevents proper preload - fix (if present) - buy a few 0.5mm shims from your LBS and install under headset cap. I had this problem on my Tarmac.
2) Are you running normal steel brake housing outer, without a ferrule on the headtube side (as is the normal construction method) It is possible the sound you are hearing is the longitudinal steel fibres have crept out of the housing "wrapping" and are brushing the cable stop as you turn bars or apply compression to the housing. This happened on my evo, and the sound drove me nuts. I also found that the steering would push to one side due to the inflexibility of the rear brake housing pushing the bars away from the headtube. Solution - use compressionless/segmented cable housing.
I now have it set up with alligator ilink housing and it is quiet as a mouse. I would not recommend AICAN bungarus, as the sharp bend the rear brake routing takes can crack the delrin liner when turning bars sharply to put bike into back of car. Nokon, jagwire elite, swift should all be fine.
My own Evo Nano Black plus my friend's Sagan limited edition have both failed within a very short time (mine lasted only three weeks, and literally turned to black paste - the ball bearings disintegrated).
With mine it seemed ok when tested at home, but on the bike you could definitely feel the play which got worse and worse.
The local (NZ) Cannondale distributor is not replacing the Nano (super light) headset bearings with the same because too many have failed. They are now issuing standard headset replacements.
Hope that helps.
OK, I will check all that and see what I can find.
I am sure there is enough space between the top of the steerer and the top cap, so will investigate everything end and let you know what I find. I didn't have any problems at all like this with my 2012 Evo; this 2014 one is comparatively much lower quality on all fronts.
Also, the HS on those bikes has to stay well-greased and clean or else they will creak/knock over time. The rear brake cable interface is another annoying source of trouble. I use some Nokon links from the cable stop to about 1.25 inches outside of the HT and then use a coupler to normal housing. I grease all of the Nokon links before installing and the cable stop heavily, then wipe the outside clean once the cable has compressed everything. No creaks there since.
NiFTY wrote:Is the headset cap (not top cap, below stem and spacers) touching the top tube? There needs to be a small gap otherwise the stem binds on the frame not on the headset and prevents proper preload - fix (if present) - buy a few 0.5mm shims from your LBS and install under headset cap.
goodboyr wrote:I would also add micro shims to ensure spacing at both upper and lower bearings. Cannondale molds are quite variable and that affects spacing and clearance at the headset molded bearing cups.
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