is this stupid way to save weight?

Discuss light weight issues concerning road bikes & parts.
mike
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by mike

remove the fork expander, which is like 40-50 grams, and use the mcfk expander bolt instead? is this a stupid and risky way to save weight? the fork expander prevents the carbon steerer from sheering if there is enough forces on it, and the mcfk bolt will not prevent the steerer from cracking.

by Weenie


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VTR1000SP2
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by VTR1000SP2

I can’t say either way but with some new bikes now providing owners the option to switch a stem or raise the stack without losing headset preload, I wonder if we’ll see more fork failures or have these steerer tubes been reinforced?


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mike
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by mike

they don't seem to be reinforced with those preload bikes come with a metal insert as well, like time bikes.

hannawald
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by hannawald

not all forks are made same way. My Bianchi has quite a thick wall..they supply with Carbon Ti expander (14g). Cannondale bikes have also very lightweight expander. On the other hand Ridley had some 60g very long expander. When I asked them, if it can be changed for something lighter, they said no.

AJS914
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by AJS914

I used to think that there was no way that you could really compress a round fork steerer tube so that a reinforcing expander was unecessary. I've changed my mind on that. I'd rather have the security of a longer expander that supports the stem for the tiny weight penalty.

My goal also isn't a bike at the bleeding edge of weight. I'm a big guy and a bike under 16 pounds is just fine for me. I could drop a boatload of weight if I bought some weight weenie wheels.

mike
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by mike

yeah, when i saw those trek bikes break at the steerer, i rethought about saving weight there.

morganb
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by morganb

mike wrote:
Fri Oct 26, 2018 6:36 pm
yeah, when i saw those trek bikes break at the steerer, i rethought about saving weight there.
My friend's Emonda ALR snapped at the steerer this year, during U23 nationals in the middle of a pack no less. Is this just on recent bikes or have they had that problem in the past too?

Marin
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by Marin

morganb wrote:
Fri Oct 26, 2018 7:24 pm
snapped at the steerer this year, during U23 nationals in the middle of a pack no less.
Just like that from normal riding? Had to be damaged previously.

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pdlpsher1
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by pdlpsher1

There are many good educational videos on YouTube about compression plugs. Like this one. If you don't want to watch the entire video just fast forward to the 7 minute mark.

https://www.youtube.com/watch?v=8bSnbjHiFXc

GothicCastle
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by GothicCastle

AJS914 wrote:
Fri Oct 26, 2018 6:24 pm
I used to think that there was no way that you could really compress a round fork steerer tube so that a reinforcing expander was unecessary. I've changed my mind on that..
The steerer absolutely compresses. Anyone can see this with a little experimentation; just insert an expander loosely in the steerer, torque the stem to 5nm and you’ll feel the steerer grab the expander. Carbon is not terribly strong in compression like that.

bm0p700f
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by bm0p700f

As I use no spacers there is almost no risk of the steerer cracking. It happened once and all spacers were ditched as a result.

jih
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by jih

bm0p700f wrote:
Sat Oct 27, 2018 10:04 am
As I use no spacers there is almost no risk of the steerer cracking. It happened once and all spacers were ditched as a result.
Could you explain how spacers increase the risk here?

bm0p700f
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by bm0p700f

I had a bit too much stack and my steerer cracked 3/4 the way through, while doing the grand fondo championships. I was only 8 miles in. The head tube in this bike is very short. After I finished I cut the rest of the steerer flattened it off removed all the spacers anfld then found the new position quite comfortable. Since then I hVe not use spacers on my bikes. It was a Columb us minimal fork too. With a long bung.

mattr
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by mattr

So no spacers is nothing to do with the risk of cracking a steerer then. The risk is having more spacers than allowed by the fork manufacturer. Or damaging the steerer when you cut it, or a faulty steerer from the manufacturer......
(I've seen it listed as between 30 and 45mm of spacers on most CF steerers. The rule of thumb seems to be between 1 and 1,25x steerer diameter.)

bm0p700f
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by bm0p700f

Actually the spacers got removed from l my bikes because I realised I could maintain z lower position than I thought.

I'd say the safe limit is the steerer diameters width on spacer stack.

by Weenie


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