Proper Use of Expander/Compression Plugs

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OlieSimpson
Posts: 78
Joined: Sat May 01, 2021 7:20 pm

by OlieSimpson

musiclover wrote:
Tue Jan 18, 2022 10:18 am
OlieSimpson wrote:
Tue Jan 18, 2022 9:49 am
mag wrote:
Mon Jan 17, 2022 12:01 am
The Colnago one is fine, no issues with slipping here.
The Deda one is fine as well, but it has slightly larger diameter. Make sure it would fit into your steerer tube (>= 23.5 mm ID) before purchasing it.
Good catch, the ID of my steerer tube is only 21.5mm so the Deda won't work unfortunately.

So...can anyone recomend something similar to the Deda 70mm compression plug that will with a 21.5mm ID steerer tube?
That's what I use. https://www.pro-bikegear.com/global/acc ... ander-long ps oh sorry it seems that it says "Minimum inner diameter: 23mm" in the description there.

You will need to search for something with your non-standard steering tube.
Yep, fortunately it means the carbon steerer tube itself is nice and thick so should be well supported, however unfortunately it means a special compression plug is needed :?

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Lewn777
Posts: 1266
Joined: Thu Mar 09, 2017 5:35 am

by Lewn777

wooger wrote:
Mon Jan 17, 2022 5:21 pm
Lewn777 wrote:
Sun Sep 06, 2020 10:45 am
Great post. We discussed this on another thread, engineers mostly suggest supporting the bottom bolt with an expander long enough to reach that far, which means use of spacers above the stem should be avoided.
Not sure that spacers are relevant really - does this not just mean that the expander plug needs to be at the same point the stem is attached? So provided you have or get a long enough bolt to reach and position the expander in the right place, why would spacers above the stem be an issue at all?
Because nearly all expanders have an upper lip where they sit on top of the steerer and the main tightening body of the expander sits on the inside of the steerer but only at the top. Therefore if you have an uncut steerer and need spacers there is no internal support for the stem when it is bolted up to torque, massively increasing the likelyhood to steerer failure. That being said you can get an expander that can be positioned inside the steerer, but those usually aren't OEM. I've got about 10 different expanders, only one that is like that and it was aftermarket and too short to support both bolts.

Personally I would prefer an aluminium sleeve bonded into the inside of the steerer and use a star fangled nut, which probably wouldn't be much heavier given the weight of most expanders.

by Weenie


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