Do you really need carbon assembly paste? The answer is actually quite simple: Assembling carbon parts on a bicycle is always a hot topic! Because carbon is – quite the opposite of iron – light, but also somewhat sensitive. Carbon assembly paste (or simply "carbon paste") helps you to securely connect bicycle parts made of carbon without damaging the expensive components.
Now you don't have to worry, a bicycle frame or components made of carbon are robust today and can withstand great forces. However, only if the forces acting on them come from the "right direction."
Why do you need carbon assembly paste?
For normal use, carbon parts are of course suitable. However, what bicycle parts made of carbon fibers cannot tolerate are point impacts or screws and clamps that are tightened too much. You cannot simply screw bicycle parts made of carbon together; the specified torque, that is, the force with which you tighten screws or clamps, must not be exceeded. To still ensure a firm connection, there is carbon paste.
If a carbon seat post or a carbon handlebar is taken into carbon assembly paste and torque wrench without a stranglehold, brand new bicycle parts can be damaged directly so that they only end up in the trash. It is even worse, however, if handlebars or seats are invisibly damaged, and it then turns out during operation that they were not as stable as you thought – it goes crack, and you already have an accident.
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Here you will learn why carbon paste helps you to mount bicycle parts safely, what carbon assembly paste actually is, and how to use it correctly. |
Contact point 1: Carbon assembly paste securely fixes a carbon handlebar in the stem. Whether the handlebar or the stem or both are made of carbon fibers does not matter. Image © Giant
How can carbon parts be damaged during assembly without assembly paste?
Let's assume you tighten screws on a carbon stem. If you tighten a screw that is in a carbon part too much, it is not the screw, which only costs a few cents, that gets damaged. Rather, the mounting eyelet tears, and the stem is then junk. If you tighten a clamp around a carbon part (for example, the seat clamp or the attachments of brake and shift levers) too much, the carbon can crack, and the diagnosis is the same: junk.
How does carbon assembly paste work?
Carbon paste belongs to the assembly lubricants. Does that mean that carbon is contained in the assembly grease? It's like the thing with toothpaste and strawberry cake – here the paste is for carbon, not made of carbon. Carbon paste contains tiny particles that improve the friction between the handlebar and stem, between the seat post and frame, or between the handlebar and the clamps of shifters and brake levers. This reduces the stress on the clamping surfaces, the clamps can be tightened with less torque and still hold firmly.
> The particles can be made of different materials: Depending on the manufacturer, glass, natural substances like pumice stone, or fibers are mixed in.
> The base paste consists of grease. Depending on the manufacturer, it can be biodegradable grease from renewable raw materials or synthetic lubricant.
Contact point 2: Shifters and brake levers (or in this case the combination of both) must be attached to the carbon handlebar. Carbon assembly paste is also used here. Image © Giant
- The tiny particles in the paste improve the friction and thus the grip between the bike parts.
- The parts then hold, even if the clamps are tightened with less torque.
- This way the bike parts do not slip , which is particularly practical for the seat post.
- At the same time, they prevent the parts from “seizing”, getting stuck so that they are difficult to loosen and replace.
- Another plus point: Carbon assembly paste can reduce or even prevent the annoying creaking that occasionally occurs between bike parts.
Some bikers are afraid of using carbon assembly paste, because if particles are contained in the paste, don't they rub and damage the surfaces of the expensive carbon parts? Here, experts and developers give the all-clear. Sure, the particles can rub against the surface of the parts. But that only happens if the bike parts move and friction occurs – exactly what carbon assembly paste prevents.
Contact point 3: The frame and seat post can be securely screwed with the help of carbon assembly paste. Image © Orbea
What should you consider when buying carbon paste?
- Carbon paste is a bicycle care product like any other. As always, it is worth paying attention to good quality in the long run and using products from reputable manufacturers.
- Residues of the assembly paste can be washed off during the next bike wash or by a rain shower and can enter the soil or groundwater. Therefore, as with all cleaners, choose environmentally friendly and biodegradable products and ensure that residues end up in the trash or the drain and not on the grass.
- There are manufacturers who place great emphasis on particularly environmentally friendly ingredients. Peatys, for example, produces a carbon assembly paste from renewable fats, with natural pumice providing the fine particles.
- You often find carbon assembly paste under the English terms Carbon Assembly Paste, Fiber Grip or Anti-Slip Paste. In German, the terms Carbonpaste or Carbon-Montagepaste are most common.
- There are guides that explain how you can mix assembly paste for carbon parts yourself. But are they recommended? ...difficult! It may be that the mixture works well. But if it doesn't, expensive carbon components are done for!
> Click here to go to carbon assembly paste in the online shop
The best carbon assembly paste is useless if you then tighten the screws too much. Therefore, always use a torque wrench! Image © Topeak
How do you use carbon paste correctly?
- Depending on which carbon paste you buy, there are different methods to apply it to the bicycle. Some products come directly with a small brush. Others you can pack into a grease gun, which is especially worthwhile for frequent users. Simply smearing carbon assembly paste with your finger is also not prohibited.
- Apply a thin layer of carbon assembly grease to the area to be clamped.
- Less is more – this not only saves your wallet but also the environment.
- Now you can place your bicycle part and tighten the screws.
- Very important! Especially when assembling carbon components, you should always use a torque wrench ! It prevents you from tightening the screws too much and causing damage.
- On the bicycle parts, the allowed force in Nm (Newton meters) is usually indicated.
- After assembly, you can simply wipe off any visible residue of the paste carefully.
On this stem, you can clearly see the allowed torques of 6 Nm and 1 Nm (even if this model is not made of carbon, maximum values apply). Image © Reverse
Is carbon paste only for between carbon and carbon or also between carbon and aluminum?
Both! With carbon paste, you can improve the grip between two carbon parts, but also between carbon and other materials.
There are bicycle mechanics who recommend carbon paste to connect bicycle parts slip-free, even if they are not made of carbon, for example, an aluminum seat post in an aluminum frame. That's fine. However, under no circumstances should a movable connection come into contact with carbon assembly paste, because the particles act like sandpaper due to the movements!
Is carbon paste not assembly paste?
Are carbon paste and assembly paste just the same? They are not, quite simply, assembly paste lacks particles. This makes the difference clear. Assembly paste lubricates. Carbon assembly paste clamps.
For more information on the correct assembly of your cockpit, you can find it in the articles "Correctly convert and adjust bicycle handlebars and stem" and "Adjust bicycle handlebars".
If you want to know more about bicycle lubrication, you can read more in our article "Bicycle Greases Explained!".
