Best expander plug with or without weight being a factor?

Discuss light weight issues concerning road bikes & parts.
alcatraz
Posts: 2103
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Some things to consider regarding slippage:

1. Not all bikes have the same fork inner tube surface smoothness. Your results could vary.

2. Torquing to the maximum specified ~8Nm for the light ones would possibly overtorque it as the tube wall becomes compressed by the stem on flexy fork tubes. Maybe avoid max torque unless you experience slippage.

3. Grabbing more surface could result in slippage. I found the extralite thin lip design to have less slippage than semilight 10gr with larger contact surfaces.

What solved many issues for us was to use a torque wrench and torque the light expanders to their max (without the stem) to get minimal slippage. If your loosened stem binds easily you might find preloading the headset with a light expander troublesome. Check the stem for burrs and go easy on the antislip paste if you use it. Ideally I'd want a stem that when loose, doesn't require too much effort to position. Not all are like that.

by Weenie


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Lewn777
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by Lewn777

alcatraz wrote:
Wed May 15, 2019 1:06 am
Some things to consider regarding slippage:

1. Not all bikes have the same fork inner tube surface smoothness. Your results could vary.

2. Torquing to the maximum specified ~8Nm for the light ones would possibly overtorque it as the tube wall becomes compressed by the stem on flexy fork tubes. Maybe avoid max torque unless you experience slippage.

3. Grabbing more surface could result in slippage. I found the extralite thin lip design to have less slippage than semilight 10gr with larger contact surfaces.

What solved many issues for us was to use a torque wrench and torque the light expanders to their max (without the stem) to get minimal slippage. If your loosened stem binds easily you might find preloading the headset with a light expander troublesome. Check the stem for burrs and go easy on the antislip paste if you use it. Ideally I'd want a stem that when loose, doesn't require too much effort to position. Not all are like that.
Interesting post. So you're saying that a smaller plug surface area reduces the chances as slipping as the pressure is in a smaller area?

Some people say rubber o-rings or even old inner tube has helped them prevent slipping, can anyoen confirm this?

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PinaRene
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Joined: Mon Feb 12, 2007 12:08 pm

by PinaRene

Lewn777 wrote:
Tue May 14, 2019 11:10 pm
PinaRene wrote:
Tue May 14, 2019 9:13 pm
Carbon - ti with Riesel topcap on 2 out of 3 bikes - they don't slip with topcap on 3Nm and it's enough for bearing preload. Did cobble rides - bad roads and they still are perfect. Ordered @ R2 bikeshop in Germany.

Cobble rides are a great test, and 3nm is a good torque, this seems like a good option. Thanks. :thumbup:
What torque are you using on the plug? 6nm?
Torque for the plug/ extender max 4Nm and stem bolts also 4Nm , works well for me.

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Lewn777
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Joined: Thu Mar 09, 2017 5:35 am

by Lewn777

The carbon-ti exapnder can be only 4nm without slipping? Impressive.
I'm running 8nm plug, and 2-3nm extender, still slips sooner or later. I just want set and forget.

alcatraz
Posts: 2103
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

I noticed your chinese grammar there Lewn777. :lol:

I'm struggling to remember mine after being there 5+ years.

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Lewn777
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by Lewn777

17 years, y u no think my grammar good? 😁

Discodan
Posts: 128
Joined: Mon Oct 16, 2017 2:55 am

by Discodan

I’ve been using a Hope head doctor for many years without fault; 30 bucks and 30 grams so reasonable.

It shouldn’t be hard to make a expander that has a reasonable ‘grab’ area and supports a decent length of the steerer from crushing, it’s not hard engineering and we probably could have made these as school metalwork projects if we had the need back then.

I think I’ll get one of these for a loss cost trial; 4 bucks for 30 grams with a decent support depth. Does anyone think the knurled finish would in anyway point load the carbon

https://www.aliexpress.com/item/1PC-lot ... 42665.html

An AliExpress WW option; 7 bucks for 7 grams. I’m not going to go there are it seems it relies on 3 ridges of 1mm to grip and support the steerer, it much work but I’m not too comfortable. How does that compare in terms of support to the established suppliers?

https://www.aliexpress.com/item/ZTTO-Bi ... 21314.html




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dgasmd
Posts: 1736
Joined: Sun Apr 15, 2007 5:10 am
Location: South Florida

by dgasmd

I have used the 2 below with out an issue at all. Got them with the same brand cap. Pretty damn light!

ImageImage

Meyercord
Posts: 58
Joined: Mon May 29, 2017 6:11 am

by Meyercord

Discodan wrote:
Mon May 20, 2019 12:21 am
I’ve been using a Hope head doctor for many years without fault; 30 bucks and 30 grams so reasonable.

It shouldn’t be hard to make a expander that has a reasonable ‘grab’ area and supports a decent length of the steerer from crushing, it’s not hard engineering and we probably could have made these as school metalwork projects if we had the need back then.

I think I’ll get one of these for a loss cost trial; 4 bucks for 30 grams with a decent support depth. Does anyone think the knurled finish would in anyway point load the carbon

https://www.aliexpress.com/item/1PC-lot ... 42665.html

An AliExpress WW option; 7 bucks for 7 grams. I’m not going to go there are it seems it relies on 3 ridges of 1mm to grip and support the steerer, it much work but I’m not too comfortable. How does that compare in terms of support to the established suppliers?

https://www.aliexpress.com/item/ZTTO-Bi ... 21314.html




Sent from my iPad using Tapatalk
Those are just clones of carbon ti and extralite expanders. I’ve used both(the real ones) and both work fine.

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FIJIGabe
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Location: The Lone Star State

by FIJIGabe

shuttlenote wrote:
Tue May 14, 2019 5:46 pm
FIJI: Is this the Bontrager you're using?
https://www.tritoncycles.co.uk/componen ... cap-p20914
It looks like it, but it's just the OEM one that came with my Emonda.
Madone 9 - https://bit.ly/2Nqedbn
Emonda SLR - https://bit.ly/2UK5FP8
Crockett - https://bit.ly/2Xem4sk

Madone 5, Cobia. I own a lot of Treks.

eric01
Posts: 614
Joined: Mon Feb 06, 2006 1:06 am

by eric01

The specialized plug is pretty good. It’s longish and relatively light weight. Less than 30g if I recall correctly
AX Lightness Vial Evo, Carl Strong Titanium

dastott
Posts: 178
Joined: Wed Jun 17, 2015 12:35 pm

by dastott

Orbital wrote:
Wed May 15, 2019 12:07 am
dastott wrote:Had slippage with the light Cannondale one recently. Have put the heavy (50g) Cannondale one back on so this thread is well timed for me. Thanks.
I initially had slippage when I went to the lighter one. Use a bit of carbon paste and haven’t had issues since.
Getting slippage with the heavy Cannondale one now too. Time to try carbon paste. Sorry for the newbie question, but where to apply the paste exactly? On the expander plug where it meets the inside of steerer, or where the stem meets the outside of steerer, or somewhere else? Thanks.

alcatraz
Posts: 2103
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

dastott wrote:
Sat Jun 08, 2019 1:29 am
Orbital wrote:
Wed May 15, 2019 12:07 am
dastott wrote:Had slippage with the light Cannondale one recently. Have put the heavy (50g) Cannondale one back on so this thread is well timed for me. Thanks.
I initially had slippage when I went to the lighter one. Use a bit of carbon paste and haven’t had issues since.
Getting slippage with the heavy Cannondale one now too. Time to try carbon paste. Sorry for the newbie question, but where to apply the paste exactly? On the expander plug where it meets the inside of steerer, or where the stem meets the outside of steerer, or somewhere else? Thanks.
At the contact points where you want to increase friction. For a compression plug this means on the steerer tube inner wall.

Just pay attention not to get it into bearings, threads, or where you don't want friction.

I find it difficult to mount a stem as the stem will scrape the paste onto the headset cap where I don't want the stuff. I guess the best way is just to apply it sparingly.

dastott
Posts: 178
Joined: Wed Jun 17, 2015 12:35 pm

by dastott

Many thanks. I have a feeling that the top bearing just under the stem keeps coming loose (because it is not seated properly?). Never had this issue before so it's very puzzling.

by Weenie


alcatraz
Posts: 2103
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Is the bearing seat ovalized or is your headset simply losing compression?

Are you torquing the stem bolts to their max and in small increments left/right?

Carbon paste helps too.

If my bearing seat were ovalized I'd try some retaining compound a la loctite 641. I'd leave it to set with preload overnight before riding to avoid it coming loose before the compount has dried.

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