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16 comments
Hi all. Been out today for a quick 50 minute ride and seem to have solved the issue. I changed to top 5mm spacer for an temporary alloy one and as said previously checked everything was in spec and assembled as per the manual. Now have a seat post squeek but that's an easy one.
Big thanks to Red Kite Cycles in Shirley was in the area for something else so popped in they gave me some 0.25mm shims which I didn't actually use in the end Really nice shop, friendly staff. Lots of bikes may have to buy an Enigma Ti from then next. Lovely!
Interesting. I took it all apart and checked it over tonight and made sure it was installed 100% to spec. The bung is torqued to 4Nm which isn't much but I will see what happens I'm riding another bike tomorrow but will give it a go Saturday.
I didn't really have many thoughts about the bung assembly but that might be something worth investigating as for the carbon spacers I don't think much of them either especially running some above the stem the contact patch isn't much I think I may also replace them.
I had problems with the headset on my Super Six Evo from the start. The supplied fork steerer "bung" to fit the carbon fibre fork was very poor quality and would not satisfactorily clamp the steerer. I've seen this exact design of bung before on other brand bikes, and its never worked properly.
As soon as I applied slight pressure through the top cap bolt to tighten the headset, this bung would move up the steerer, preventing the headset from being torqued (only 2-3nm). I tried fibre grip (carbon past) and setting torque on the bung using a torque wrench but it made no differentce.
I then replaced this with a spare bung from a Specialized S-Works, and applied fibre grip paste. This allowed me to tighten the headset properly.
The second problem was the headset still coming loose whilst riding, and creaking. This was tracked down to the supplied carbon fibre stem spacers which had a very minimalist cut away design with only 3 points of contact.
Similar to the ones above, but with even more cut out leaving three triangular contact points. These barely made contact with the stem body.
I replaced these with aftermarket spacers of solid carbon fibre (not cut away) and the problem never occured again.
Cannodale specifically say no spacers above the stem in the manual. They don't mention assembly paste but they do for the seatpost. They are very specific on lots of things it's the craziest manual i've ever seen i think they may even describe how to ride a bike!
But i get your point.
"Shouldn't really put spacers above the stem but the press review bikes from Cannondale usually do so don't think that's the problem"
er, you should always place one spacer above the stem*, because the steerer needs to protrude from the stem, then the spacer is needed so the top cap doesn't pull down and contact the steerer, instead pulling down on the spacer->stem and then onto the bearing topcap. And so the steerer can't be pinched by the stem clamp. Anything to not introduce fractures.
People who insist on cutting their steerers right down to the stem du jour aren't thinking about ever a: changing stem or b: selling their bike. Which is OK, of course.
I acknowledge some folks use the top few mm of the stem as a spacer, to separate steerer from topcap. Done carefully, that's OK - but you are loosing clamping area betwixt stem/steerer. Which especially for carbon is not good.
...and if it's a carbon steerer, you should use paste. Best practice.
* this from p340, 'Zinn and the art of road bike maintenance'. Trust Lennard, not Some Guys On Road.CC (including me)![smiley smiley](/sites/all/themes/rcc/images/smilies/16.gif)
It's an odd one some headsets come with a shim because with the bearing they decide to use the collet won't hit hit the bearing top cover cane creek & FSA do it on some headsets I'm sure many other do.
I was thinking along the same lines to be honest Nixter at least it would then iliminate this as an issue. I can fudge something together.
The stem is 100% undone when I adjust the headset.
Another thought, have you loosened the steerer clamp bolts on the stem before tightening the top cap? Tightening the top cap without loosening those bolts will have no effect on bearing preload
Nixter understand your comments and this is how mine is setup it's a new frameset so wear isn't an issue. Re the last couple of lines of your comment. It seems some frames may not be 100% to spec and require a 0.25-0.5mm shim under the headset upper race. If the bearing sits low in in the cup the upper race will bottom out on the top face of the bearing before it compresses the collet properly and you end up being unable to set the preload.
so I'm going to
1) check the length of the expander assembly so it meets the drawing.
2) Try to buy some micro spacers (fsa make them but I can't see any stock in the uk) I think this is what steve_williams may be referring to. Steve if your still watching this thread where did you get them.
http://www.fullspeedahead.com/products/cyclocross/micro-spacers/
I hadn't encountered the issue with out of tolerance you refer to but (assuming I'm understanding you correctly) you could check this by removing the bearing top cover completely and just using a spacer stack to compress the collet directly. This wouldn't be a long term solution (aesthetically at least) but you would have narrowed down the causes/ solutions. Surprised that the dust cap hasn't fouled the top of the head tube and stopped the bars turning though?
Within reason, it doesn't greatly matter how many spacers you have above or below the stem as long as:
1) the expander part of the bung is within the part of the steerer clamped by the stem
2) the top spacer (or the stem clamp) protrudes by at least 3mm and better 5mm above the top of the steerer tube
Torque the expanding part of the bung to the required value then the top cap to compress the headset and lastly (sorry if this is obvious) the stem bolts.
If this doesn't sort it then the lower bearing may be worn - depending on the age of the bike obviously. I find that after fitting a replacement lower bearing that it beds in after a while and needs to be re-done to take out play. The lower bearing is always the one that goes, I've replaced two and the upper bearing is still smooth.
If you're using the Cannondale headset top cap, by which I mean the one immediately next to the upper bearing, there shouldn't be a need to put a spacer above the collet.
Ha! Really not that flexible to many years sitting behind a desk! From the geo chart and a drawing I did at work probably going to end up with 30-35mm. Not very Pro.
You don't need assembly paste. I think the point is to use one of the spacers from below the stem, even a 10mm would be fine. I actually ran mines pretty much slammed for a few weeks before getting the steerer cut without issue.
The spacer I linked is from cannondalespares.com - but you'd only need it if you're looking to go super low.
Yep torqued the bung with a torque wrench to spec in the manual. Didn't use carbon assembly compound though because it doesn't mention it in the manual are you using any?
I haven't checked the depth of the bung but that's a good point it is mentioned in the manual I will look tonight.
I have seen other people adding a spacer above the collet that holds the top bearing in but I can't seem to source anything in the uk less than 1mm in .1/8. Where did you source yours from?
Shouldn't really put spacers above the stem but the press review bikes from Cannondale usually do so don't think that's the problem.
As above, I had this problem after changing stem and to cure it I had to add a small spacer to allow a slight gap above the steerer tube so it would clamp down properly.
If I'm right in remembering the manual, you need at least 5mm above and below the stem (you absolutely shouldn't be screwing the top cap on to the steerer!).
It comes with that ridiculous conical spacer on the bottom but I replaced it with this: http://www.reveloutdoors.co.uk/img/products/csg/hscd99kp253-400.jpg
Is the bung close enough to the top cap to let it screw in properly to eliminate play, and are you tightening to the right spec (ie using a torque wrench to do it)?
Can't say I've had issues with mines before (apart from dropping the bung all the way down the steerer and spending 20 minutes fishing it out!)