A local Retro-Modern bike shop in West Seattle.    RideYourBike.com    

Carbon Fiber Care and Warnings

Let it be known that Aaron's Bicycle Repair, Inc. does not condone or endorse the use of carbon fiber.
We do not hate it. We are only concerned about our customer's safety since carbon fiber has the potential to be a very dangerous product.
Carbon fiber is RACE USE ONLY material. It is designed for world-class racers only.
It should only be worked on by the most highly skilled mechanics. Carbon fiber is not user serviceable!
Our experience in the shop finding many damaged carbon fiber parts has given us this opinion.
The real world is much tougher on carbon fiber than any testing lab! People are not always as careful as they should be with their bicycles.
Carbon fiber parts should be treated with the same care as a fine crystal wine glass!

We do work on many racers (or racer types) carbon fiber dream machines but we are always trepidatious about it and we decline if they start wrenching on it themselves.
Carbon fiber cannot be visually inspected and many parts have only a one-season life span.

Will not do any work on any bike with visibly damaged carbon fiber.
Not even a flat! Bring us the wheel instead.

Any carbon fiber bike or part that has been in a crash or hit by a car should be replaced!
Watch the below video to find out why.

We will not work on repaired carbon fiber frames repaired by anyone other than the below links or the original manufacturer.
We recommend Calfee or Joe's Carbon Solutions for carbon fiber frame repair. We will not work on repaired carbon fiber forks or components. We will not work on repaired carbon frames unless you have a certificate from a reputable company.

Carbon fiber parts should be considered disposable or consumable, like a Bic lighter!

We will not work on any steel frame bike with a carbon fiber seatpost because carbon fiber seatposts are forbidden in steel frames due to the pinching force of the clamp. Carbon fiber seatposts require that the clamping force be opposite or 90 degrees from the slot. Also, carbon and steel will bond together worse than any aluminum post ever has.

Carbon fiber steer tubes should NEVER have a star-fangled nut driven into them! Some Cannondale bikes have that done and that is the only exception we will work on. Industry standard for spacers under a stem is 40mm. Easton allows 50mm. Carbon steer tube forks must have the original stem of the same brand installed. Some stems are not compatible with carbon steer tubes.

THE NUMBER ONE DAMAGED CARBON PART WE SEE IS THE SEATPOST. NUMBER TWO IS THE STEER TUBE.
Both are very high stress items and should be replaced with metal. (see pictures below).

We will only sell components, bikes and frames from the allowable list.

Allowable:

Derailleurs
Shift Levers
Brake Levers
Chainrings with aluminum teeth
Bottom Bracket Shell
Hub Center Shell
Fork Legs (only)
Seat Stays
Dust Caps & Spacers (Headset, BB, Hub, etc)
Carbon Fiber Handle Bar Tape (Yes, they make it!)
Shoe Soles
Helmets

Not Recommended:

EVERYTHING ELSE! (including but not limited to):
Handlebars
Stems and Face Plates
Seatposts
Seats and Seat Rails
Chainstays (on an aluminum frame)
Drop-Outs (Frame & Fork Legs)
Steerer Tubes
Full Carbon Frames
Cranks
Chainrings with carbon teeth
Hub Flanges
Rims
Spokes
Brake Calipers
Fenders & Water Bottle Cages (broken carbon is razor sharp!)
Carbon Bolts

Trek's Official Carbon Fiber Warning
Trek's Carbon Steer Tube Care
Specialized's Fork Installation Instructions
Easton's Fork Installation Instructions
Reynold's Fork Installation Instructions
Why Thompson doesn't use carbon fiber.
Busted Carbon Blog

If you have a carbon fiber steer tube, we STRONGLY recommend this aluminum insert.
If you buy it we can install it.

Our 2007 crop of broken carbon fiber:

Summer 2009 Crop


Here is what Lon Kennedy, owner of Nova Cycle Supply (a wholesale supplier of Columbus carbon forks) has to say:
From an email:

From: Lon Kennedy
To: Tech Info at Nova
Sent: Monday, January 28, 2008 9:47 AM
Subject: Re: Carbon Steer Tube Damage?

Aaron,

Given the pictures, and not the part itself, my opinion is that the steerer appears to have cracks that would make the fork unsuitable for use.
Possible reasons for failure generally fall into 2 categories. My explanations are general and since I do not have the part in front of me to make a specific determination, are for your reference.

Rupture failures
1) Placement of the expander cap in an area not constrained or supported on the circumference by the stem or overtightening the expander cap.
As you are probably aware, general correct assembly practice is to make sure that the expander itself is surrounded by the stem to support it and prevent rupture failures.
Perhaps, too many spacers?
Snakebite failures

2) The stem has some areas of contact that are not carefully deburred as part a correct assembly routine. If the slot or the top or bottom or the stem is not properly deburred a crack can be initiated by the non-deburred area (sharp edge) scoring the steerer tube and initiating a crack.
My opinion is that the fork is unsafe to use given the appearance of cracks.

Hopefully this will help you in your assessment.

Lon/NOVA

Below are the pictures of the fork discussed in the above email.

More pictures of failures.

Below is damage to a fork from SKS Race Blade fenders.
The damage is caused vibration and the dirt that gets under the mount.
Current Race Blade fenders come with clear plastic protective stickers. You can also use several layers of electrical tape.

Bike Reflector thru Chainstay!

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