The bikeImprints (may be called witness marks) on the steerer can form from a loose headset. We should all periodically inspect our carbon forks. One example is below finished Unbound Gravel in 2023, from this question. There wasMy understanding is that this is repairable, that it isn't a complex job, and that it's not very high-attrition mud section on the course. Note the concentric rings in the abraded sectioncostly -(source Raoul Luescher, Escape Collective Discord). Contact your local repairer. If they can't do it, I'd seek a second opinion; the mud abradedrepair techniques should have spread through several layers of carbon. This is another visible failurethe industry, but not all repairers may know them.
Last, the bike below finished Unbound Gravel in 2023. There was a very high-attrition mud section on the course. Note the concentric rings in the abraded section - the mud abraded through several layers of carbon. This is another visible failure. Again, this needs repair for sure. However, it is repairable.
The above cases describe visible damage. This section concerns what to do if you sustain an impact that doesn't leave visible or other obvious damage. For major impacts like a car vs. bike accident or a crash at racing speeds, more caution is recommended. This is a harder question.
With that trivial question out of the way, it is frequently hard to know what to do if you crash on a carbon frame or component and there's no obvious damage. Damage to carbon items is frequently not visible at the surface. However, an impact, even a fairly soft one, might lead to a delamination below the surface that later grows into a larger failure. Delamination is the CF term of art for a fracture.
Ultrasound or other imaging is used to inspect CF parts in the aerospace industry. Ideally, we would have this capability widely available, but we do not. This is the only reliable way to detect a delamination under the surface. There may be a carbon repair shop close to you with this capability, but your local bike store cannot do this. Many people will propose a tap test, where you tap a coin lightly around the suspected fracture and listen for a change in pitch. Raoul Luescher says that this test can work on flat surfaces of constant thicknesses. However, bikes have a lot of curvature and varying thicknesses. Rob Granville of Carbon Bike Repair concurs, with a video demonstration. If you do try this, you are listening for a marked drop in pitch.
Otherwise, I would propose watchful waiting for lighter impacts where you can't see damage. Be familiar with how your bike sounds and how it flexes under your pedaling. If you notice a sudden change, stop riding and try to see if there are any cracks. You are looking forThey may be small cracks. ForIf you had a heavy impact, e.g. car vs. bike, I would lean more towards finding a repairer to inspect.
One example of a small fracture is below, the picture below is from a video by Raoul Luescher, a carbon bike repairer based in Australia. Here, a metal part associated with the steering system hit the bike's head tube from inside due to arguably poor design. There was a small visible crack from the outside.
I believe that forks, wheels, stems, and handlebars are not cost effective or possible to repair (aside from the ring of death above). This was reported by some carbon repairers who have appeared on podcasts like the old Nerd Alert (Cyclingtips, now defunct) or the Marginal Gains podcasts. There's no harm asking a repairer near you, but you should prepare to replace these components if damage is suspected. Many premium wheelsets are starting to come with free crash replacement guarantees for the original owner. Otherwise, manufacturers typically reserve some rims and other spare parts for warranty and repair cases.
The bike below finished Unbound Gravel in 2023. There was a very high-attrition mud section on the course. Note the concentric rings in the abraded section - the mud abraded through several layers of carbon. This is another visible failure.
This section concerns what to do if you sustain an impact that doesn't leave visible or other obvious damage. For major impacts like a car vs. bike accident or a crash at racing speeds, more caution is recommended. This is a harder question.
With that trivial question out of the way, it is frequently hard to know what to do if you crash on a carbon frame or component and there's no obvious damage. Damage to carbon items is frequently not visible at the surface. However, an impact, even a fairly soft one, might lead to a delamination below the surface that later grows into a larger failure. Delamination is the CF term of art for a fracture.
Ultrasound or other imaging is used to inspect CF parts in the aerospace industry. Ideally, we would have this capability widely available, but we do not. This is the only reliable way to detect a delamination under the surface. There may be a carbon repair shop close to you with this capability, but your local bike store cannot do this. Many people will propose a tap test, where you tap a coin lightly around the suspected fracture and listen for a change in pitch. Raoul Luescher says that this test can work on flat surfaces of constant thicknesses. However, bikes have a lot of curvature and varying thicknesses. Rob Granville of Carbon Bike Repair concurs, with a video demonstration. If you try this, you are listening for a marked drop in pitch.
Otherwise, I would propose watchful waiting. Be familiar with how your bike sounds and how it flexes under your pedaling. If you notice a sudden change, stop riding and try to see if there are any cracks. You are looking for small cracks. For example, the picture below is from a video by Raoul Luescher, a carbon bike repairer based in Australia. Here, a metal part associated with the steering system hit the bike's head tube from inside due to arguably poor design. There was a small visible crack from the outside.
I believe that forks, wheels, stems, and handlebars are not cost effective or possible to repair. This was reported by some carbon repairers who have appeared on podcasts like the old Nerd Alert (Cyclingtips, now defunct) or the Marginal Gains podcasts. There's no harm asking a repairer near you, but you should prepare to replace these components if damage is suspected. Many premium wheelsets are starting to come with free crash replacement guarantees for the original owner. Otherwise, manufacturers typically reserve some rims and other spare parts for warranty and repair cases.
Imprints (may be called witness marks) on the steerer can form from a loose headset. We should all periodically inspect our carbon forks. One example is below, from this question. My understanding is that this is repairable, that it isn't a complex job, and that it's not very costly (source Raoul Luescher, Escape Collective Discord). Contact your local repairer. If they can't do it, I'd seek a second opinion; the repair techniques should have spread through the industry, but not all repairers may know them.
Last, the bike below finished Unbound Gravel in 2023. There was a very high-attrition mud section on the course. Note the concentric rings in the abraded section - the mud abraded through several layers of carbon. This is another visible failure. Again, this needs repair for sure. However, it is repairable.
The above cases describe visible damage. This section concerns what to do if you sustain an impact that doesn't leave obvious damage. This is a harder question.
Damage to carbon items is frequently not visible at the surface. However, an impact, even a fairly soft one, might lead to a delamination below the surface that later grows into a larger failure. Delamination is the CF term of art for a fracture.
Ultrasound or other imaging is used to inspect CF parts in the aerospace industry. Ideally, we would have this capability widely available, but we do not. This is the only reliable way to detect a delamination under the surface. There may be a carbon repair shop close to you with this capability, but your local bike store cannot do this. Many people will propose a tap test, where you tap a coin lightly around the suspected fracture and listen for a change in pitch. Raoul Luescher says that this test can work on flat surfaces of constant thicknesses. However, bikes have a lot of curvature and varying thicknesses. Rob Granville of Carbon Bike Repair concurs, with a video demonstration. If you do try this, you are listening for a marked drop in pitch.
Otherwise, I would propose watchful waiting for lighter impacts where you can't see damage. Be familiar with how your bike sounds and how it flexes under your pedaling. If you notice a sudden change, stop riding and try to see if there are any cracks. They may be small. If you had a heavy impact, e.g. car vs. bike, I would lean more towards finding a repairer to inspect.
One example of a small fracture is below, picture from a video by Raoul Luescher, a carbon bike repairer based in Australia. Here, a metal part associated with the steering system hit the bike's head tube from inside due to arguably poor design. There was a small visible crack from the outside.
I believe that forks, wheels, stems, and handlebars are not cost effective or possible to repair (aside from the ring of death above). This was reported by some carbon repairers who have appeared on podcasts like the old Nerd Alert (Cyclingtips, now defunct) or the Marginal Gains podcasts. There's no harm asking a repairer near you, but you should prepare to replace these components if damage is suspected. Many premium wheelsets are starting to come with free crash replacement guarantees for the original owner. Otherwise, manufacturers typically reserve some rims and other spare parts for warranty and repair cases.
