Steering tube Expander bung vs Star Nut

[Cramer Long]

Has anyone ever used an expander bung ? Wondering if so How easy they are to remove ? It appears you'd just loosen it and pull it out . I want to use one in the top half of a Delta Steering tube extension. If anyone is familiar with the Delta extension . You know what I mean

TY

 

[Cramer Long]

Does anyone even know what a bung is ?

 

[stw]

Has anyone ever used an expander bung ? Wondering if so How easy they are to remove ? It appears you'd just loosen it and pull it out . I want to use one in the top half of a Delta Steering tube extension. If anyone is familiar with the Delta extension . You know what I mean

TY

I always use an expander thingie or bung when setting up a threadless bike. They have never failed or caused any problems, and the ones I've used do come easily right out as you described. They are required for carbon steerer tubes I think, but I use the expander even in steel steerers that are tolerant of banging in a star nut. I haven't installed a star nut in years, although I'll still use one if it's installed in a fork already. I think of the star nut as a relic of the first days of the threadless headset when something cheap and secure was needed. They're still cheap and secure but I prefer the expander.

I'm not familiar with the Delta extension. I assume it has it's own secure mounting process and is not relying on the expander/start nut to hold the fork (or expander) in place while the headset is adjusted(?). In the early days of threadless headsets people had the idea the bolt from cap into star nut held the fork in place, but it only does helps pull the fork into proper headset adjustment. After that it's the clamped stem that holds the fork in the bike and you could ride without the cap/bolt/expander if you wanted with the same function until you needed to adjust the headset.

 

[Cramer Long]

I always use an expander thingie or bung when setting up a threadless bike. They have never failed or caused any problems, and the ones I've used do come easily right out as you described. They are required for carbon steerer tubes I think, but I use the expander even in steel steerers that are tolerant of banging in a star nut. I haven't installed a star nut in years, although I'll still use one if it's installed in a fork already. I think of the star nut as a relic of the first days of the threadless headset when something cheap and secure was needed. They're still cheap and secure but I prefer the expander.

I'm not familiar with the Delta extension. I assume it has it's own secure mounting process and is not relying on the expander/start nut to hold the fork (or expander) in place while the headset is adjusted(?). In the early days of threadless headsets people had the idea the bolt from cap into star nut held the fork in place, but it only does helps pull the fork into proper headset adjustment. After that it's the clamped stem that holds the fork in the bike and you could ride without the cap/bolt/expander if you wanted with the same function until you needed to adjust the headset.

What I want it for which is a little hard to explain . Isn't what the traditional use would be . The Delta is a steering tube extension . It is different then the average one because the bolt that screws into the Star nut is at the bottom of the extension . Which is 2.5 inches or 64 mm down inside the tube . The Top cap threads on . the ID measures 22.3 mm .
I can use a longer bolt and use any cap I want . However I want to install a Rocform bracket (PICTURED)
I can use a longer bolt and be good to go . However this bracket has a tendency to loosen the Blot . WHich I'm sure you know loosens the front fork . ; So I was thinking an expander plug inserted above the shorter bolt . Would give me an anchor point for the Rocform bracket that is separate from the bolt holding down the extension to the steer tube. . If the thing comes loose from there it won't effect my front Fork .

I could also use a extra star plug . If I go that route and need to remove the stem for some unforeseen reason . I'd have to cut it off .
An expander plug /bung . Would allow me to just pop it out if I had to service the Steering tube .
A star plug would also likely destroy the Threads at the top of the delta extension on the first install.

It may not even work . I can only find one expander plug in the 1" size I'd need . Obviously not much call for 1 inchers . Plus I doubt anyone else has thought of my idea .
I hope I explained this clearly

 

[stw]

Your thinking makes sense to me--to use a short bolt to secure the Delta Extension in a dedicated way that's not affected by the Rockform bracket. Then use an expander to bolt the RockForm to. Avoiding a star nut is good thinking because it would prevent access to that Delta extension bolt below as you say.
In a regular threadless fork install where the stem-clamp holds the fork in and holds the headset adjustment, a longer bolt would be just fine for the Rockform--if it loosened, then it doesn't affect anything to re-tighten as long as you don't loosen the stem clamp bolts. But with your Delta Extender, it's good to use the most secure mounting for that and a separate bolt for the RockForm.

 

[Cramer Long]

Your thinking makes sense to me--to use a short bolt to secure the Delta Extension in a dedicated way that's not affected by the Rockform bracket. Then use an expander to bolt the RockForm to. Avoiding a star nut is good thinking because it would prevent access to that Delta extension bolt below as you say.
In a regular threadless fork install where the stem-clamp holds the fork in and holds the headset adjustment, a longer bolt would be just fine for the Rockform--if it loosened, then it doesn't affect anything to re-tighten as long as you don't loosen the stem clamp bolts. But with your Delta Extender, it's good to use the most secure mounting for that and a separate bolt for the RockForm.

Not sure what you mean . It's a Specalized Vado . If the Rocform flips around it does loosen my front fork. The torque spec is only 6NM I suppose I could loctite the Bolt in place . Maybe MTB setup is different ??? I'll have to look closer . As this really is something I'd rather avoid doing if I can . Like I said it may not even work.

 

[stw]

Here's how I think through it: the standard method for a threadless bike setup is you tighten that top cap bolt to pull the fork into proper headset adjustment, not too tight, and on your bike that cap would be the RockForm so the bolt tightens the Rockform too. Once you have the headset adjusted you tighten the stem bolts that clamp stem to steerer, and now the stem clamp is what is holding your fork in and maintaining your headset adjustment. On a regular bike, you only keep the cap/and bolt in place so you can re-adjust the headset out on the road if needed, and perhaps for a back-up holding your fork in your bike in case your stem bolt(s) failed (unlikely but backup is always good). In your case you'd also ride with cap and bolt in place because the cap is your RockForm.

If your fork does loosen when your RockForm/top-cap loosens and flips around, I'd be concerned you're not clamping the stem properly after adjusting the through bolt. Because on a regular threadless set up, the fork should not loosen if the top cap loosens (or even is removed) as long as the stem is properly clamped to steerer.

However, on your bike with the Delta steerer extender installed (into?) the steerer, there may be something else happening--perhaps the fork is moving relative to the Delta Extender if the Extender installation is not preventing that? Even in a regular threadless set-up with no Extender, you do not want to rely on the top cap (in your case RockForm) and bolt to be the thing that holds the fork in place as you ride. That's the stem clamp's job. I would think that would be even more true (not relying on the top cap/RockForm) if you also have a jointed steerer, which is what I'm assuming the Delta Extender in your steerer produces(?).

 

[Cramer Long]

Here's how I think through it: the standard method for a threadless bike setup is you tighten that top cap bolt to pull the fork into proper headset adjustment, not too tight, and on your bike that cap would be the RockForm so the bolt tightens the Rockform too. Once you have the headset adjusted you tighten the stem bolts that clamp stem to steerer, and now the stem clamp is what is holding your fork in and maintaining your headset adjustment. On a regular bike, you only keep the cap/and bolt in place so you can re-adjust the headset out on the road if needed, and perhaps for a back-up holding your fork in your bike in case your stem bolt(s) failed (unlikely but backup is always good). In your case you'd also ride with cap and bolt in place because the cap is your RockForm.

If your fork does loosen when your RockForm/top-cap loosens and flips around, I'd be concerned you're not clamping the stem properly after adjusting the through bolt. Because on a regular threadless set up, the fork should not loosen if the top cap loosens (or even is removed) as long as the stem is properly clamped to steerer.

However, on your bike with the Delta steerer extender installed (into?) the steerer, there may be something else happening--perhaps the fork is moving relative to the Delta Extender if the Extender installation is not preventing that? Even in a regular threadless set-up with no Extender, you do not want to rely on the top cap (in your case RockForm) and bolt to be the thing that holds the fork in place as you ride. That's the stem clamp's job. I would think that would be even more true (not relying on the top cap/RockForm) if you also have a jointed steerer, which is what I'm assuming the Delta Extender in your steerer produces(?).

OK great > That's easier and less expensive . Now all I need is a 6m stainless bolt 120mm long . The one that came with another extension is to short at 110mm Hopefully my hardware has these

 

[Stefan Mikes]

Cramer, I can hardly understand the nature of your problem but I'll help you with some information:

1. Delta Stem Riser is not any different from any other steering tube extension. It should be bolted from the top, tghrough the cap.
2. The torque on the steerer bolt shall never be excessive. It should be sufficient to prevent vertical movement of the fork but is should be mild enough not to compress the steerer bearings or prevent the handlebars to rotate easily. For that reason, torque wrench is never used on that bolt, and the torque is applied by trial-and-error method.
3. The Rokform mount should be designed to be able to act as the steerer tube cap. If it is not strong enough, it is a wrong product.

 

[Cramer Long]

Cramer, I can hardly understand the nature of your problem but I'll help you with some information:

1. Delta Stem Riser is not any different from any other steering tube extension. It should be bolted from the top, tghrough the cap.
2. The torque on the steerer bolt shall never be excessive. It should be sufficient to prevent vertical movement of the fork but is should be mild enough not to compress the steerer bearings or prevent the handlebars to rotate easily. For that reason, torque wrench is never used on that bolt, and the torque is applied by trial-and-error method.
3. The Rokform mount should be designed to be able to act as the steerer tube cap. If it is not strong enough, it is a wrong product.

Yeah that's what I figured when I ordered the Delta extension . They must have changed it . The One I received has M6 x 50MM Bolt . Which fits down inside the tube . Then the Top Cap is plastic and threads on . I can do what you are suggesting . I have compression caps . I just can't find a Bolt online that's long enough without buying a dozen . Then I'm not sure the thread pitch will be right . Maybe with Metric Bolts it doesn't matter . Most stuff in America is non Metric . So it's hard to find a Bolt that's 6M x 120MM . Which appears to be what I need to install that Rockform using the Delta .

 

[Stefan Mikes]

Yeah that's what I figured when I ordered the Delta extension . They must have changed it . The One I received has M6 x 50MM Bolt . Which fits down inside the tube . Then the Top Cap is plastic and threads on . I can do what you are suggesting . I have compression caps . I just can't find a Bolt online that's long enough without buying a dozen . Then I'm not sure the thread pitch will be right . Maybe with Metric Bolts it doesn't matter . Most stuff in America is non Metric . So it's hard to find a Bolt that's 6M x 120MM . Which appears to be what I need to install that Rockform using the Delta .

Something is wrong here Cramer. If you bolt the Delta by the bottom, the whole extender above will flex, making the whole thing inherently unsafe.

 

[Cramer Long]

Something is wrong here Cramer. If you bolt the Delta by the bottom, the whole extender above will flex, making the whole thing inherently unsafe.

Yeah I wondered about that . But they must have designed it that way . As the Cap that comes with it screws into threads . There is also no way to put a bolt thru the cap supplied with the Delta extension. So this must be intentionally designed this way . It's really heavy duty . I ordered a Satori along with the delta . I sent the Satori back as the wall thickness of the Delta was notably stronger .
If I can find a long enough 6m bolt I can mount it either with the Rocform Cap or one of my others . There is a plug on the delta cap that can be drilled out . Except the cap is plastic . The only way to know if this isn't a error is to call Delta and ask. As it was in a factory sealed wrap. We all have ordered stuff from Amazon that someone else had purchased and sent back . This was definitely not that .
When I get an answer I will let yah know . By the way this delta I purchased has a star nut way down at the bottom . In the area where what I would call the base slips over the steering tube . So this has to be their latest design . I tried to move it thinking at first it had slid down. On close inspection I see it's molded into the unit's walls on purpose. For reference I used the link you had posted in another thread for this same extension. So maybeeee it's your fault ? ha ha JK . I plan to call them shortly when they open

 

[Cramer Long]

Something is wrong here Cramer. If you bolt the Delta by the bottom, the whole extender above will flex, making the whole thing inherently unsafe.

Got hold of Delta right when they opened . What I described is intentional . The threaded Cap area also has a small shelf . So if you want to use a conventual bolt from cap to star nut . You can do so without the need of a Spacer for the cap to set against . I was informed their Delta extension is rated something something something tensile strength . She said it so fast I didn't catch it to write it down. I did catch that it is strong enough and the Pro length also have been tested on To Speed decent Downhill MTB? Think that's how she worded it . Anyway it won't bend lol . I told her my situation with not being able to source a long bolt for My Rocform. I was informed that it's a standard 1. pitch that would be on any 6m or M6 bolt . They recommend staying with 304 stainless (WHich is the normal you find anyway) So Now I just have to source a long bolt