Carbon fibre brake lever DIY

I bent a brake lever on my Hygia SLP brakes . I'd already tried to got in contact with the local distributor about a bleed kit and olives. Disappointingly, I didn't hear anything back from them. Is it really too much to ask to reply to an email asking a simple question like "where can I buy a X, I live in Y?". The local distributor has set prices about 50% higher than what they sell for off fleabay so there really should be some margin for them to answer emails about where to buy their stuff.

Once I bent the brake lever back into shape I got thinking about making a stronger lever from carbon fiber.

Here's what I did:

Make a mold

The first step is to make a mold of the existing brake lever. I used the lever from the side that wasn't bent (the levers on the Hygia SLP and identical left to right). There are plenty of articles on the internet about how to make a fibreglass mold of a plug or part. Check those out for the details. The only real trick here was to use an appropriately bent aluminum plate to support the lever:

Making a mold for carbon fiber brake lever

Make the lever using the mold

I get any pictures of this part of the process. You'd really need someone just operating the camera. Once the expoxy resin is mixed you want to move quickly and with sticky resin all over your gloves its not really conducive to getting the camera out.

For layup I used alternating layers of unidirectional and cross weave fibre in 25mm ribbon. There are 9 layers of carbon fiber in the lever blade. It is hugely over-built compared to the pressed aluminum original. The carbon fibre version is twice as thick.

I vacuum bagged the lever once layed up using nylon release cloth at the back of the lever.

Pop it out of the mold

Here's the original aluminum lever and the carbon fiber lever fresh from the mold. You can just see a corner of the fibreglass mold in the top right of the picture:

Carbon fiber brake lever fresh from the mold

Machine it

Machine in the holes and slots necessary for the pivot and brake actuator/adjuster:

Lever almost finished

Test assembly

Reassemble the brake with the new lever:

Brake system test assembly


The original lever weighed 8 grams and the carbon fiber lever weighs the same. This may seem surprising but the carbon lever is about twice the volume of the aluminum lever. It is much stronger for the same weight.

Material quantities used

The 25mm carbon weave ribbon weighs 6.92g/m. The unidirectional carbon ribbon weighs 8.66g/m. In total I used 5 x 14cm of weave and 4 x 14cm of uni ribbon. So a total of 9.7g of carbon fibre. There was not too much excess trimmed, but I didn't weigh the off-cuts. Assuming 30% was trimmed then there is about 6-7g of carbon fibre in the lever and 1-2g of resin.

Finished product

Glossy... (finish coat of gloss 2 part polyurethane)

Final picture of lever with glossy 2 part polyurethane

On the bike:

Finished CF brake lever fitted to brake master cylinder

Next time...

For the next set of levers I am going to make a new mold. My first mold was pretty quick and dirty, just to check out the entire process and workflow. For the next mold I will use tooling gelcoat before beginning the fibreglass layers. Also, I will attempt to include in the mold the little slot in the front of the lever for the engagement point access. It was quite difficult to cleanly machine in this slot. Having at least its outline or a depression as part of the mold would produce a much neater end result.

I am also tempted to produce an ultra-light lever version. These would incorporate a layer of kevlar and less layers of carbon fiber in the lever blade. The kevlar will not add to the strength of the part but should hold things together in the event of a catastrophic failure.


Hygia are now making carbon fibre brake levers for the SLP. They are about 2g lighter than the aluminium levers.

Related articles:

TruckerCo Brake Pads

These are the TruckerCo brake pads organic semi metallic for Magura MT2, MT4, MTS, MT6, MT8.

Magura MT series brake pads

Magura genuine

DIY Frame Bag

There's not alot of space for a frame bag in the main triangle on the Giant Anthem X (especially if you want to keep your water bottle). I made this bag to take up as much ...

DIY Micro Tank Bag

This has to be the smallest tank bag out there. I designed it to fit my Nokia 6120c and nothing else. Total weight is 12g and its about 150mm long, 50mm wide and 20mm high. Its ...

EBC red disc brake pads

I've been using a set of these on the front with my Magura MT8/MTS brakes:

Ultralight XTR Brake Pads

These brake pads from Discobrakes are for Shimano XTR, XT, SLX and LX disc brakes as well as Hygia SLP and Elite disc brakes. They are aluminium backed and weigh only 8g for ...