This doesn't look right to me

[Shewie]

I felt like there was some play in my headset on my last ride so had a look last night, took off the top cap and a couple of spacers and found this ..

20230131_153125 by Shewie, on Flickr

20230131_153131 by Shewie, on Flickr

Should that be flush with the top of the fork cut? There's every chance I've caused this myself by overtightening the top cap bolt before I had a clue about spacers and headset compression. Is it just a case of giving it tap back in or does it need replacing?

Edited to add ..

If it does need a tap back in, is there a good chance it will just come out again easily?

[faustus]

Yep, should be flush! Loosen it and move it down then re-tighten. Then don't overtighten the top cap. To be honest i've had mixed results with carbon steerer bungs. Some kept coming loose no matter what I did, or how much carbon paste I used. If it does it again then look for ones with a large grip area - like this one:


A lot more points of grip with the file texture, compared to the selcof bung.

[Lazarus]

What they said and undo it before tapping flush don't just hit it.
Don't undo it so much it falls apart...learnt that the hard way.

[Shewie]

Thanks guys

How do I loosen it, which part has the adjustment?

[Bearlegged]

There should be a hollow allen bolt in the centre, it may be quite deeply recessed. Loosen this, move the bung down so it's flush, then tighten. Your stem cap bolt will then screw into the hollow allen bolt.

[Shewie]

thanks guys, job done already

Any recommended torque for nipping up such a bolt.into a carbon fork?

[redefined_cycles]

thanks guys, job done already

Any recommended torque for nipping up such a bolt.into a carbon fork?

Light as possible just to tuck it in there. Like about 5nm or less

[redefined_cycles]

Better quality bungs do actually grip better. The cheap stuff is just cheap and lacks grip etc.

[redefined_cycles]

Oh and lastly... Remember this isn't actually holding everything together. It's only there for preload of the bearings then you'll fasten the camp around the steerer tube which is what holds everything (obviously you know that but just reminding). Weight weenies actually use the system then discard it once the preload is done and everythings clamped

[Shewie]

thanks guys, job done already

Any recommended torque for nipping up such a bolt.into a carbon fork?

Light as possible just to tuck it in there. Like about 5nm or less

I've had to go way beyond that Shaf, I'm probably nearer 15-20nm, I've cleaned everything and lathered up with carbon paste but it still creaps out with minimal load on the top cap bolt so not sure I fully trust it.

I think I might buy a replacement, the one faustus linked to looks like it's a much better design, I'll measure the ID of my steerer and get one ordered

[redefined_cycles]

thanks guys, job done already

Any recommended torque for nipping up such a bolt.into a carbon fork?

Light as possible just to tuck it in there. Like about 5nm or less

I've had to go way beyond that Shaf, I'm probably nearer 15-20nm, I've cleaned everything and lathered up with carbon paste but it still creaps out with minimal load on the top cap bolt so not sure I fully trust it.

I think I might buy a replacement, the one faustus linked to looks like it's a much better design, I'll measure the ID of my steerer and get one ordered

Herein lies your problem Rich. Carbon paste isn't to be used there mate... Try and het it back out (carefully) then clean all the carbon paste away. Friction is your friend. Same goes with (for example) spark plugs. Once you add any friction reducing stuff like copper ease then the handbooks suggest you need some extra leverage. Technically it's not needed there either but inside a carbon steerer to make the bung stick it's best with the paste.

I'd argue that the one you're using is beyond it's sell by date (and if it's from any of the bike manufacturers in their generic builds, will be the worst/cheapest bung ever) and it's probably time to just get a fresh one

Sorry to sound like the bearer of bad news and I'm happy to be proven wrong by any of the specialists on here... But, worked for me

[redefined_cycles]

Lol... Sorry again (in advance) but I just relooked at your original pics. Yes, the design you have in there seems to be ready for the bin (before it even went in) and the fact that you have a Selcof headset makes me think the bung is probably worth about 50p in manufacturing terms.

Two more things... Surface area with friction is your best friend. Lose the paste. Check the inside of your actual steerer tube as it might just now be too smooth (which isn't the end of the world) and need a little bit of roughness with some lightly gritted sandpaper.

Once you have the headset bearings nipped/preloaded down then (I can't think of any) there's not much reason for the cap to come back up. Hence I'd have thought/said the whole system or more than just the bung is failing. The stem might not be gripping the steerer appropriately and/or your bearings might be out.

Once all nipped back up do the 'rock the forks with brakes on and wheel angled' test. Pop your hands around the top and bottom bearing areas and feel for play. Bet you find a fair bit

Ignore everything if you find a better solution elsewhere

[Shewie]

Ordered a nice blingy gold Cane Creek jobby

[redefined_cycles]

I'd not condone buying an Enve and I'll not link you to the forum I found this (cos they on that particular forum sound a bit like they don't know much really - sorry). But they seem to agree with the (roughly) 5nm figure. Not seen the vid or if they suggest using paste but I'll not be doing anything so daft. The figure Enve seem to suggest is 8nm and don't forget that most torque wrenches of the smaller/cheap-ish variety will find it really hard to actually give a correct resding at that range.

Hence it's always best to get used to the pinch with finger tips or do it up FT (patent pending - another Stu off this forum who's a truck mechanic) unless you wish to spend on laodsa a various calibrated torque wrenches.

https://m.youtube.com/watch?v=cQe9TJJq1PE

[redefined_cycles]

Ordered a nice blingy gold Cane Creek jobby

now you're talking

[Cheeky Monkey]

Herein lies your problem Rich. Carbon paste isn't to be used there mate... Try and het it back out (carefully) then clean all the carbon paste away. Friction is your friend. Same goes with (for example) spark plugs. Once you add any friction reducing stuff like copper ease then the handbooks suggest you need some extra leverage. Technically it's not needed there either but inside a carbon steerer to make the bung stick it's best with the paste.

Shaf - are you confusing greases and lubes with carbon (or, as it's commonly also referred to, FRICTION) paste?

Carbon / friction paste is intended to improve grip which is what's needed if the bung is slipping, much like you can benefit from a smear on a carbon seatpost to help stop moving.

Happy to be corrected if I've got the wrong end of the stick

Edit - added a quote though on re-reading you seemed to go both ways

[redefined_cycles]

https://www.amazon.com/Park-Tool-Superg ... B07BMQHCJ2

Yes, this stuff Tim. I dontuse it on the steerer bung but do use it on carbon seatposts (or metal seatposts into carbon seatubes, or even the tiniest of smears around the steerer where the stem clamps, or around the carbon handbars where the stem clamps as it'll save from any sort of oxidaxtion issues etc etc). I don't believe it's designed to be used around the outside of the alloy bung and dontuse it personally but totally understand why/if others would want to use it.

YMMV and all of that

*Even used it on carbon road bars where the levers clamp the bars but found it to break down the compound that's around that part.. so now add some nail polish and let dry before adding a touch of friction/carbon paste. Quite a lengthy subject is carbon paste and it's uses and why (I think )... For example, using standard lube/grease on carbon has the risk of breaking down the resin/polymers/whatever. Am sure Stu has alot more thoughts/knowledge in the matter...

[jameso]

Carbon steerers are suprisingly elastic and expansion bungs can stretch them out if overtightened so if carbon paste reduces that, go for it. A better bung design would be preferable though.
One thing I'd also do is fit the steerer is all the way through the stem so the stem has a 5mm spacer on top to create compression space. Get all the stem to steerer clamp area you can.

[Bearbonesnorm]

Shaf, also worth noting that some fasteners should be lubricated before tightening and the recommended torque setting allows for this. Also 'copper paste' isn't a lubricant and will do no harm when fitting spark plugs etc and may save much grief later on. However, rubbing the tip of a pencil over the threads before fitting will also help prevent them seizing especially in alloy heads

[redefined_cycles]

Thanks for the tip of the pencil Stu- makes sense. Yes, copper paste I only ever use as an anti sieze (took almost half an hour getting a 19mm bolt off the brake calipers off the lexus using heat aswell, but have added some copper paste now) and always apply it to any bolts I ever work with anywhere (but not excessively).

Regards using carbon paste on the bung James. The grit of the paste (in theory) would have a tendency of sitting in the knurls/grooves of the outside of the alloy bung. So all that's left touching between the bung and the inside of the steerer is the slippery/lube part of the paste. Hence it's not doing much other than maybe creating a bit of slip

That's why I don't use it anyway and have done so in the past with much problems of slip

[redefined_cycles]

https://youtu.be/8bSnbjHiFXc

For completeness of info and since the threads open. Maybe the above deserves a place here (Rich, he's one of the best carbon repair chaps who can be bothered to share his knowledge on the net). The number for elasticity is 2% and hence why you wouldnteant to overtorque.

Since you've pushed the torque up to about 20nm, (I hate to be the bearer of poor news) it might be worth giving the fork steerer a once over with your fingers and maybe a light/magnifying glass to check that youvenot done any damage to the fibres...

For ref Rich (sorry if you already know this) Jameso is one of the frame designers who bought us the Pinnacle Ramin/Arkose and the likes so they both are higher in the pecking order of info in terms of frame materials and engineering etc

[jameso]

Regards using carbon paste on the bung James. The grit of the paste (in theory) would have a tendency of sitting in the knurls/grooves of the outside of the alloy bung. So all that's left touching between the bung and the inside of the steerer is the slippery/lube part of the paste. Hence it's not doing much other than maybe creating a bit of slip

That's why I don't use it anyway and have done so in the past with much problems of slip

That makes much sense.. I've seen and specced a few that are fairly smooth but maybe the smoothness is why they needed paste sometimes

I decided the cover-all solution for me was steel steerers / forks, but I know that's not the popular way to go these days.

RE pecking order of materials and engineering, thanks for the kind words Shaf but I won't claim to be an engineer. There's enough mock engineering in the bike industry already Designer / product manager, with some engineering common sense maybe but a little knowledge is a dangerous thing and I'd defer to a Mech Eng every time on anything structural.

[redefined_cycles]

Regards using carbon paste on the bung James. The grit of the paste (in theory) would have a tendency of sitting in the knurls/grooves of the outside of the alloy bung. So all that's left touching between the bung and the inside of the steerer is the slippery/lube part of the paste. Hence it's not doing much other than maybe creating a bit of slip

That's why I don't use it anyway and have done so in the past with much problems of slip

That makes much sense.. I've seen and specced a few that are fairly smooth but maybe the smoothness is why they needed paste sometimes

Funny you should mention this James. I was actually thinking to update/qualify my statements of 'no carbon grit paste' but thought against it as no one likes a 'know it all'

So, what I was gonna add is that some of the better/best steerer bungs I've used (from Triton Cycles IIRC was probably one of the best surfaced) actually have the surface area gritted. Like literally feeling like rough grade sandpaper and these grip like no-ones business. If I bought a steerer bung that had no 'grittiness' or knurls (is that the correct term for that textured surface that's still cheaply made), then it'd make sense to get some carbon/grit paste in there.

For the record (this is in case anyone didn't realise and it's not been mentioned before), the paste/grease part of carbon paste is actually friendly to the polymers inside the carbon. Using anything else (unless it states 'carbon friendly' would case a mushy mess of the carbon unless it had been treated properly with some sort of sealant coat - nail varnish was mentioned by one of the carbon repair chaps in a Rouleur interview of old).

BTW James, you're (and many/most others on here) so humble and that's why we all love this place. Long live BearbonesBikepacking Forum... I suppose

[Shewie]

Got my replacement bung expander thingy in the post today ..



Should I remove any carbon assembly paste I have in the steerer tube after faffing with the original crappy PX bung? There's no mention of using paste in the instructions ... https://canecreek.com/wp-content/upload ... ctions.pdf

I'm thinking it probably won't do it any harm and to just leave it

[Bearbonesnorm]

I'd leave it Rich.