Wheels - Carbon brake track

Hey all,

Looking for a bit of advice. Although I think it’s looking like I’m going to need a new bike :sweat_smile:

Carbon brake tracks, please see pictures below. When cleaning them today I noticed the small raised areas in a few spots on the front wheel surface. Rear is smooth :ok_hand:

The wheels were not bought new so I dont know their history. The bike is my pride and joy and so in my ownership they have been cared for! Recommend pads always used.

I’m always careful to pulse my braking in short bursts, I am 85kg so I do take some stopping…particularly on my local 25% hills!

Any advice or thoughts based on the pictures, I know they’re probably as useful as a chocolate teapot :rofl:

It’s hard to tell from the pictures, but it does look like there is some brake track wear (which is normal and not of concern). I cannot distinguish any raised areas, but those would be cause for concern if they looked like bubbles or any other signs of delamination. Perhaps another angle or light angle could give us a better idea? And perhaps an arrow to the area of concern?

Although, If it will help the case with the significant other: I would condemn the whole bike, and suggest a full and immediate replacement :wink: For safety, of course.

1 Like

I don’t think there is any way for us to tell from pictures. If you are concerned, go to a bike shop you trust and ask them for advice.

Quite generally, though, I’d add two things: first of all, you should be able to trust your equipment. If you don’t trust your brakes, then this is no bueno as they say in the industry. You also should not meter your braking, but instead focus on learning proper cornering and braking technique. Secondly, on a rim brake bike, your rims are a wear item. While you should avoid e. g. dragging your brakes as that would accelerate wear, you should on the other hand not overly avoid usage in situations where it makes sense to use brakes.

If you have an older bike and, e. g. you for some reason don’t trust your brakes as much as you should, then I recommend you get a new bike with disc brakes. You’ll not only get lighter actuation and much better modulation, in case of disc brakes, you will be able to replace all the wear items. Overheating will never be an issue in practice, especially on a road bike. Rotors last an eternity and even Shimano’s most expensive DuraAce rotors cost $80-$100 (depending on the size), which is way cheaper than new rims. Of course, you could save some money and get e. g. XT rotors for $50 as well.

Mavic iTigMax promo bumf…

“Improved stopping power is thanks to Mavic’s iTgMax carbon technology. The secret behind the excellent braking is said to lie in the manufacturing process. The company has a patented process which uses a laser to prepare the braking surface. This burns away the surface resin leaving the carbon fibres intact and exposed. It has also developed a heat curing process to ensure that its rims can tolerate braking temperatures of up to 200ºC, which is at the extreme of potential real-world conditions.”

So from that I’d surmise that the rough track is correct and its your smooth rear thats slightly worn…

The surface layer of carbon cloth looks intact. Looks like you have just worn away the surface resin.

Do carbon rims have a published brake track minimum thickness threshold one can verify with a caliper gauge?

There is no standard for wear. A micrometer measurement is typically used as a reference, and in the past we would replace alloy rims when they became visibly scalloped or at ,3mm wear, as I would with a disc rotor (I came from a MTB background). A carbon rim, I would replace if the top layer of resin were completely removed, or I could identify any indication of delamination or damage.

I wasn’t expecting a standard - more a manufacturer-published limit for a given product. That would make sense since the brake track is on a structural part.

I agree that a manufacturer published limit would make sense, but I have not seen one for carbon wheels (and I have been working on or with them in some capacity since 2007).

Opinion- For most, a visual inspection is a better indicator. Carbon brake pads are designed to take most of the wear, and variance in mold and brake track constructions only complicate measurements. The only brake wear related failure I have experienced was on an early 2010’s carbon rim, which had clearly melted/worn the resin and had begun to fray the carbon. I discovered it while cleaning the bike with a sponge.

1 Like

Thanks for the replies all, these wheels are covered by warranty so ill contact Mavic and see what the score is with them.

The surface is smooth when new, on another site a few have mentioned they have experienced a similar observation which resulted in a successful warranty claim. The wheels have only done around 7k miles.

Will update with any response from Mavic