Six mistakes that could damage a carbon fibre road bike frame

Oct 19, 2023

Carbon fibre is a great material for bikes, but it can be fragile. Here's how to avoid damaging your bike.

Junior Tech Writer

Carbon fibre bike frames are more susceptible to damage than alloy or steel frames. When working on, moving or storing a carbon bike, you need to be careful not to do anything that could lead to completely preventable damage. Here are six common mistakes that you need to avoid.

Fabio Jakobsen and his snapped Specialized Tarmac SL7

Clamping your frame in a work stand to carry out routine maintenance on the surface is a simple task. However, clamping in certain places could be very damaging to the frame. Carbon fibre is designed to be very strong in its intended axis, but carbon tube profiles are typically not designed with clamping forces in mind and therefore clamping on the main tube profiles of the frame could lead to cracking and damage. Clamping the bike in place should be done on the seatpost as this is specifically designed to withstand the clamping forces.

This not only applies to work stands but also anywhere you might be wanting to clamp your bike in place, such as a bike rack on a car. Some bike racks that clamp the frame are carbon-friendly as they do not exert the clamping force on the tubes themselves, but it is always best to check with the manufacturer for suitability.

How you leave your bike, either at a cafe mid-ride or at home, could lead to completely avoidable damage to the frame. Leaning the bike precariously can not only lead to it falling over but it can also fall foul to rotating handlebars. This can be especially damaging on bars that are not fully wrapped, since a solid carbon or aluminium bar rotating into the frame can cause cracking or at the very least paint chips to your carbon beauty. To ensure this mistake does not happen, lean your bike against a fixed surface with the saddle and the handlebar firmly in contact and the bike at a slight angle so that it cannot fall away to the side.

Always be careful when travelling with a carbon-fibre bike.

When travelling with your bike, it is common to need to remove a lot of the components that make a bike a bike. It is typical that when packing a bike for travel that both wheels are removed, and when doing this the frame and fork dropouts lose a lot of strength as there is no compressive brace. This means that in the event that the box or bike gets squashed these dropouts are subject to a lot of stress that can cause fatigue and stress fractures in the carbon. The best way to mitigate this is to use a combination of a hard shelled bike box and a dummy hub that sits in between the dropouts to act as a compressive brace.

Bikes are becoming more versatile and the rise of bikepacking and multi-day adventure riding is lending itself to riders carrying more and more on their bikes. It's important to bear in mind when loading up on your next multi-day ride that carbon fibre components will have a manufacturers stated maximum weight limit. This is the safe limit that the frame or component will have been tested to and loading up more than this limit could be very costly.

This maximum weight limit is often displayed as a maximum rider weight but is actually a whole system weight taking into consideration yourself, your riding kit, and luggage and its contents. Essentially anything that is going to be on the bike should be taken into account.

This is arguably the most common and likely mistake to inadvertently cause damage to your carbon frame. A dropped chain will fall into the gap between the inner chainring and the frame, if this happens the best course of action is to stop pedalling immediately and pull over to extract the chain by hand, this process should still be carried out with care as even the act of removing a dropped chain can cause damage to the frame. In the unfortunate case that you realise all too late and you have pedalled with some power after the chain has dropped you might not be so lucky. A lot of frames have either a clear vinyl sticker or a metal plate to protect the chainstay however this can only do so much and this does have the potential to write off your carbon frame.

The best course of preventative action is to ensure that your front derailleur is correctly set up and your lower limit screw is set correctly to prevent this from happening. For a belt and braces approach, if your frame does not come as standard with a chain catcher, this small device can sit behind the front derailleur and fills the void between the inner chainring and the frame.

Make sure the seatpost is within the minimum insertion line.

The final mistake that could cause damage to your carbon fibre frame is setting your seat height above the minimum insertion depth that is marked on the seatpost. The seat tube and seatpost are both areas that take a lot of load and stress, it is important that there is enough overlap between them to share this stress. Incorrectly setting the seat post height above the minimum insertion line can cause stress points that can lead to carbon failure.

There are two remedies if you are facing this issue. Firstly, fitting a longer seatpost will allow you to run a higher seat height without exceeding the minimum insertion depth. It is important if doing this to ensure (especially with aero posts) that it is the correct size and profile for your frame. If you are in any doubt it is always advised to contact the frame manufacturer. Secondly, you may be looking at needing a different size frame. Bike manufacturers stock each size bike with a seat post that should cover the range of rider size expected to suit that frame, and if you are needing to raise your seat post beyond the minimum insertion depth it could be a telltale that your frame is actually too small for you.

Impressive sprinter - quite possibly the fastest member of the GCN team