Expansion plug?

Discuss light weight issues concerning road bikes & parts.
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TonyM
Posts: 3245
Joined: Thu Jan 22, 2015 4:11 pm

by TonyM

Hi,

Which brand/ model of expansion plug would you recommend for a carbon fork/ steerer?

by Weenie


Bigger Gear
Posts: 469
Joined: Fri Mar 27, 2009 6:58 pm
Location: Wet coast, Canada

by Bigger Gear

Generally I would recommend the one that the manufacturer supplies with the fork. Each mfr has a reason for supplying it, either because it's considered "structural" like Colnago's long plug, or whatever other reason.

Having said that, the relatively cheap FSA expander with the alloy cap is very versatile, grips well and is pretty gentle on the inner steerer wall.

icantaffordcycling
Posts: 358
Joined: Wed Jan 09, 2019 5:03 am

by icantaffordcycling

The enve one is fantastic. No complaints and looks cool
Specialized Allez Sprint 2019 (In Progress)
Instagram || Shitposting is a god-given right.

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Lewn777
Posts: 808
Joined: Thu Mar 09, 2017 5:35 am

by Lewn777

Most manufacturers recommend supporting the bottom stem bolt, which as Bigger Gear said makes the expander structural. It's very tempting to go with a tiny lightweight plug like a Extralite Ultrastar 3, being weigth weenies, who can blame you from wanting to take grams off your bike, and it's an area with a good weight to cost ratio, but I consider this item more for a hillclimb race bike than an everyday climbing bike. Even though there are very few or no reports of steerer failures I personally defer to the engineers that designed my bike and run the stock expander. If the original is a real boat anchor, I would replace it with one of similar dimensions.

RocketRacing
Posts: 820
Joined: Thu May 10, 2018 2:43 am

by RocketRacing

Good point on supporting the bottom of the stem, given the choice.

I always went with the “i am light, so i can get away with it”. Now i realized that i can put out decient watts, so it has me thinking...

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TonyM
Posts: 3245
Joined: Thu Jan 22, 2015 4:11 pm

by TonyM

Thanks for the feedback.

I see that Deda has 2 expander plugs.
45 and 70mm!

http://www.dedaelementi.com/en/expander-45/
http://www.dedaelementi.com/en/expander-hss/

alcatraz
Posts: 2144
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

If you expand the bottom of the stem you can have the headset loosening by itself. The stem rides upward to the marginally lower diameter by vibration alone.

I'm not saying not to do it, just to watch out for it.

Bigger Gear
Posts: 469
Joined: Fri Mar 27, 2009 6:58 pm
Location: Wet coast, Canada

by Bigger Gear

alcatraz wrote:
Wed May 01, 2019 3:36 am
If you expand the bottom of the stem you can have the headset loosening by itself. The stem rides upward to the marginally lower diameter by vibration alone.

I'm not saying not to do it, just to watch out for it.
I think you mean if you expand the fork below the stem right? Like the expander sitting below the stem and pushing out the steerer wall a tiny fraction. I've never considered this, but any bike that I've wrenched on where the headset comes loose persistently I've had good luck with either carbon paste or gently sanding the inner wall of the steerer to hold the expander better.

warp
Posts: 26
Joined: Fri Jun 01, 2018 3:59 am

by warp

Now that you mention that, my Canyon Ultimate doesn't use a expander at all.

1415chris
Posts: 1278
Joined: Sat Apr 18, 2009 8:59 am
Location: Surrey UK

by 1415chris

1 1/4 makes a difference.
I used to have Canyon Ultimate slx years ago, I don't know what they use in their current bikes, but at that point there was only plastik ring you just simply stick on the top of steerer tube. More aesthetical than functional reason.

I also had a bike where I was experiencing what alcatraz described above.
Currently this is my second bike where I use Extralite expander, hard to argue with its weight and damn good functionality.

3Pio
Posts: 1252
Joined: Wed Mar 09, 2016 7:13 pm

by 3Pio

TonyM wrote:
Wed May 01, 2019 2:04 am
Thanks for the feedback.

I see that Deda has 2 expander plugs.
45 and 70mm!

http://www.dedaelementi.com/en/expander-45/
http://www.dedaelementi.com/en/expander-hss/
Measure inner diameter of the fork and see if it's compatible with the expander plugs u consider..

For example on my Cannondale CAAD12 i wanted to have long fork expander (to be able to use more spacers), so as first i considered Deda 70mm.. Then i realized is not compatible but fraction of mm...

At the end i order Colnago Fork Expander which match the fork inner diameter and also is longer then Deda..... Even it's not weight weenie part..

by Weenie


jeanjacques
Posts: 190
Joined: Thu Apr 14, 2016 11:01 am
Location: France

by jeanjacques

Begin with a very light one and with this thread: viewtopic.php?t=151670 I change for a Specialized Swat, 40mm support and a chain breaker on it, both is lighter than a same size convetional expander and a chain breaker.

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