Bicycle Mechanics - Them Carbon Steerer Tubes...

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View Full Version : Them Carbon Steerer Tubes...


GMM
04-12-12, 10:20 PM
Swapped stems, retightened the top cap's plug(the compression device located inside the steerer tube) because I noticed it had pulled out slightly, when all of a sudden, 'tink!'. Guessing a 'tink' noise translates into, 'that carbon fork's a goner!'

Assuming it is: What do you think about using epoxy to glue an aluminum sleeve inside the carbon steerer tube? Would that stabilize any issues?
-OR-
Trim 20mm of steerer tube?

Already ordered a replacement fork, regardless. (LBS recommended)

UPDATE:
LBS clearly informed that full-carbon forks are NOT repairable under any circumstance, even through trimming. Once the 'tink' noisr presents, the fork must be replaced.


Shimagnolo
04-12-12, 10:41 PM
Some forks come with an aluminum insert which is glued in after cutting:

http://www.alphaqbike.com/performance_tubing/insertsystem_s.asp

My Calfee has one of these.

Kimmo
04-13-12, 01:09 AM
Guessing a 'tink' noise translates into, 'that carbon fork's a goner!'

Certainly not a good sign... although who knows? It might be fine.

If there is a crack (which I'm afraid seems likely), and you can find it, both your proposed methods of repair seem like they'd stand a pretty good chance of working, if done well.

If it turns out you have choice between adding material or removing it to fix the problem... that should be a no-brainer.


ivan_yulaev
04-13-12, 01:45 AM
Maybe the compression plug slipped up? If the carbon is actually breaking I doubt it would make a tink, more like *crack* or *crunch*.

Kimmo
04-13-12, 01:52 AM
Depends on the size of the crack, not to mention all the other factors that have a bearing on the acoustics of it...

How hard did you tighten the plug to cause this sound? Was the stem clamped around the steerer at the time?

GMM
04-13-12, 12:30 PM
How tight? I'm guessing between 3 and 5Nm's, the stem was slacked and the 'tink' noise was medium-loud.

GMM
04-13-12, 12:49 PM
Skip it... I don't think it's a good idea to fidle with carbon anything once a 'tink' noise presents.

The replacement fork has an aluminum crown/steerer.

Should friction compound also be used with aluminum steerer tubes; even with alloy stems?

fietsbob
04-13-12, 01:29 PM
Purpose? in consumer level kit, sales.
want the latest cutting edge stuff, from the pro race scene?

that is the way they went..

But You don't have to..

The Carbon blade, alloy steerer tube combination is in between.
all metal and all carbon, won't weigh a lot more..

GMM
04-13-12, 01:32 PM
Some forks come with an aluminum insert which is glued in after cutting:

http://www.alphaqbike.com/performance_tubing/insertsystem_s.asp

My Calfee has one of these.

Seems like that should be standard on every full-carbon fork. Do you epoxy it in place?

GMM
04-13-12, 01:38 PM
Purpose? in consumer level kit, sales. , want the latest cutting edge stuff
from the pro race scene?

that is the way they went..

But You don't have to..

The Carbon blade, alloy steerer tube combination is in between.
all metal and all carbon, won't weigh a lot more..

I actually held off for a year before deciding on this frameset just because it included a full-carbon fork, which i really didn't think was such a good idea.
in my opinion, carbon frames/forks blades = okay. steerer tubes/drops = no. I just don't think safety is worth shaving an extra 100-200 grams?

fietsbob
04-13-12, 01:57 PM
well there are $100 carbon forks , and there are $400+ ones
alpha Q is on the higher end of the price spectrum.
Calfee is not a discount frame either.

yea 200 grams is a good weight for the sliced meat and cheese for a sandwich.

Shimagnolo
04-13-12, 02:13 PM
Seems like that should be standard on every full-carbon fork. Do you epoxy it in place?

It was NOS, and the frame/fork and been assembled once, so it was cut and the insert was already installed. The instructions stated epoxy was to be used, and I got the impression it was included when shipped. I just used spacers to accomodate the cut length when I built the bike.

unterhausen
04-13-12, 02:16 PM
alpha Q is on the higher end of the price spectrum.

sadly, not any more, they're gone

mmmdonuts
04-13-12, 02:28 PM
A tink'd fork is teh suck.

The downside to the Alpha-Q insert is that it was a one time permanent deal. Once you cut and glued in the sleeve you couldn't ever change it.

My Alpha-Q has a steel steer tube. I'll never tink this one.

Shimagnolo
04-13-12, 02:28 PM
sadly, not any more, they're gone

Damn. Looks like they quit making forks at least 2 years ago.

Shimagnolo
04-13-12, 02:30 PM
A tink'd fork is teh suck.

The downside to the Alpha-Q insert is that it was a one time permanent deal. Once you cut and glued in the sleeve you couldn't ever change it.

Their instructions allow removing up to 2cm after the insert is installed.

Shimagnolo
04-13-12, 02:33 PM
I got curious what Zinn was doing for tall forks now, since he used to sell a special Alpha-Q with a loooong steerer. Looks like Serotta is his current source: http://zinncycles.com/Zinn/index.php/components/forks

mmmdonuts
04-13-12, 02:42 PM
Their instructions allow removing up to 2cm after the insert is installed.

Ah. I didn't know they allowed for that.