I have had some increasing issues with my headset recently. Lots of creaking no matter what I did.
After inspection is was clear that the C-ring was the culprit (as others have discovered). It just doesn't have enough wrap-around angle. You can see on the picture how much pressure is on the edges of the c-ring, causing rubbing and creaking.
I know Velobuild have made an updated version that might be better, but i wanted a significantly better version. My idea was to use the c-ring from the Specialized SL7 (the replacement after recall). It seems like a good design that wraps all the way around (95%) but doesnt need the hydraulic lines to be broken. The main problem is that it is made for a Ø40.5mm inner dimension bearing. Its also too thin to be a direct replacement.
Sourcing the SL7 c-ring (ID: s212500016) was a bit of a pain. Specialized was slow to send it to my local dealer (3 weeks). On top of that the price was high (35$ + shipping) and the customer service was terrible. The holy trifecta of a shit deal - but it worked out in the end.
I work in engineering so I called in favor to get the c-ring lathed down to Ø40 (a little tricky with an open ring) and I got a small spacer made for purpose. Spacer measurements are Ø30.9 x Ø28.9 x 2mm (stainless steel). Fits just as intended with the one piece handlebar. I have gone for a couple of rides now and I cant get a single creak out of the headset no mater how much I pull and twist on the bars.
Dear Velobuild - Please spend the extra $10-15 dollars on a proper c-ring design like this one. It is sooo much better.
Fully agree, the stock C-ring is just horrible.
In my case, it was two main issues and i guess many others suffer from that too (maybe without knowing the root cause).
Wanted to post this in the headset play issue thread but since its corrupted and you mentioned this topic here I also want to put in my two cents.
The C Ring is way too stiff since its just massive. Due to that, the headset needs to be compressed with a lot higher force than its made for in order to cause the elastic deformation of the C clip which is needed to close the gap between inner bearing ring and fork tube (which is what it is all about in order to avoid headset play).
I guess this is why many people complain about headset play even though they tightened everything. Also the stated problems with de-formed top caps might be a result of the high compression forces.
I could solve it the following way:
I found there is a noticeable play between C-ring and Fork tube (if you just put the C-ring on the fork tube). Like stated above, excessive tightening of the headset is needed in order to cause this bulky monster of a C-ring to deform elastically that much that any play is gone. Therefore i pre-compressed the C ring with a vice (carefully, gradually) to cause a plastic deformation so that in the end it sits really tight on the fork tube (almost had to stretch it in order to get it on the fork tube). This brought the headset compression / tightening torque to a regular level and the system was without play. Furthermore i needed a shim in order to maintain a small gap between top steerer tube und first spacer / dust cap device, - even though i definitely received the most recent version of the c-Ring which should already have solved that problem. That fix worked pretty well, no further isues noticed even though i tested it in rough road conditions.
In the end i equipped the bike with a one pro handlebar (which i can only recommend, - purchased unbranded directly from the manufacturer through alibaba for 95 dollar, looks really good and in total saves almost 200 grams). It comes with Spacers and a way better C-ring. With this C-ring, the needed elastic deformation can be caused with the small finger which is how it should be. Unfortuately that one was too thick, causing a huge gap between steerer tube top and first spacer. I fortunately have access to a lathe and with a little creativity the part could be clamped and machined there.
All in all a much better and lighter system and i can't imagine that the use of such a c-ring would cause any problems in the cost planning of vb.