We’re a little over a week into February. I’m still working on this bag of Counter Culture Big Trouble. Punxatawny Phil claimed we have six more weeks of winter; the Baltimore area forecast certainly agrees.

This week I’ll be covering a few phonomena that can occur with forks. Carbon, steel, and aluminum steerers all present their own form of Achilles heel when it comes to neglect or improper installation.

Let’s jump into it…

Expansion Plugs

It is my experience that a majority of carbon fork expansion plugs experience two main issues: being installed without enough torque and/or being pulled up by an overzerlous headset adjustment.

When bikes come in for evaluation, I often find the expansion plug has moved anywhere from 1-3mm above the steerer. This is typically a sign of a headset frequently coming loose, needing adjustment multiple times but the top cap is now bottoming out on the expansion plug.

It’s a fairly easy remedy depending on the interface.
Have a look at some examples below.

Stem Damage
Torque wrenches are a cockpit’s best friend. The handlebars, stem bolts, steerer, and seatpost all benefit from the use of a quality torque wrench.
Ignoring the recommended torque can be a hazard to you as well as your riding buddies. Failed componentry because of loose or broken parts from under or over torquing can be avoided by using a torque wrench and regular inspection and service.
Another issue that can occur is a poor stem to steerer interface that causes the stem to dig into the steerer. This impression can lead to a stress riser which can lead to failure. This is a critical item to check for especially on gravel bikes. Raoul Luescher has a great video on the subject embedded below this slideshow.

Have a look at some examples that have come into the shop.

Ring of Death

Sounds scary, right? It’s a term coined by the man Raoul himself.
This is a situation frequently caused by riding on a carbon fork with a frequently loose headset or a loose headset going unresolved. Remember those pesky loose expansion plugs up above? That’s one culprit.

The sensations of a loose headset vary on frame, fork, and headset design. Some will sound like a bit of a rattle on rough terrain or when portaging the bike; some instances will cause fork chatter under braking; it really depends on the set up.

A majority of headsets incorporate an aluminum split wedge that engages the inner race of the top bearing. It is splayed against the bearing race by downward pressure from the top cap that sits below the stem. Some companies opt for a plastic split wedge which I have not seen cause the R.O.D.

Okay but what is the ring of death, Tommy?
Right! So; the ring of death is the indentation and damage caused by riding with that loose headset for too long. And maybe it’s been adjusted and it’s good for a while and then comes back.
Why is that? Putting it in simple terms: there isn’t enough material supporting the split wedge to engage with the bearing’s inner race. All that steerer material has been compressed or worn away leaving a stress riser and possible delamination. The headset can’t maintain its adjustment.

Have a look at what I’ve come across.

This is a prime example of why it’s important to perform an evaluation before any type of service. Especially on a bike that’s never been in my hands.

The ring of death is a complicated issue. Carbon fiber as a frame and fork material has been forced onto shop floors by every major manufacturer. To my knowledge, retailers and service shops have not been given nor offered any type of training to navigate the complexities of carbon damage inspection.

If your shop is asking you to stop riding and replace the fork; they’re saying it out of concern for your safety and the shop’s liability. The cost of replacing is less than a trip to the ER or worse. I’ve spoken to Raoul about the ring of death and the best course of action is to send it off to be scanned if damage/wear is minor.

Bearing Damage

This one is quick.
I’ve only seen two instances where an integrated carbon fork crown races was damaged by fitting a wrong bearing.
Unfortunately, I could only find one photo from an evaluation. The crown race is designed for a 36-degree inner race chamfer. The one I pulled off was a 45-degree which had left an imprint.

Corrosion of Comformity
What do you get when you add moisture, a steerer, some spacers, and a lack of maintenance?

You got it. Corrosion.

Our sweat is not friendly to bikes. It gets into areas that don’t receive much attention because they’re typically static elements of a bike (i.e.: steerers and seatposts). The corrosion causes expansion and friction which makes removal precarious and time consuming. Something to pay attention to during warmer months and also outdoor winter riding.

Have a look at what’s hiding in wait for when it’s time for some extensive TLC.

This was a three cup edition.

Forks are a dynamic and complex piece of equipment. The responsibility a fork holds is immense- ride comfort, stability, durability, serviceability; these are just a few jobs that a fork must perform.

If you’re in the Baltimore area; I invite you to sit in on your bike’s evaluation. It’s an opportunity to better understand your bike, digest the process that goes into prescribing service, and to build a rapport together.