The Maintenance Issue: Part 4

Robbe Smith
October 23, 2024 • Estimated Reading Time: 10 minutes

In today’s send I’m going to talk about maintenance again and will cover trimming brake lines and cables for a clean cockpit.

Sometimes I feel like I am talking into an echo chamber, so I would like to open it up for questions. If you’ve got a question you’d like for me to address in the newsletter, simply hit “reply” and respond with your question. I won’t include the name of the person asking the question unless they specifically ask me to include it.

How to trim cables for a clean cockpit.

When bikes leave the factory there is a really good chance that bike was never atually assembled. While this process makes sense for manufacturing, it doesn’t help with having a clean cockpit once the bike is assembled. Something like this won’t affect how the bike rides, but it will affect how it looks. This definitely falls under a nice thing to do if you like looking at a tidy cockpit.

Most mountain bikes today will have between two and four things on your bars that require wires or brake lines. They are the shifter, dropper post lever, and two brakes. Until wireless brakes become a thing(I really hope that never happens), you will always have brake hoses or cables coming from the bar.

For this you will need a bike work stand, cable snips, 3mm 4mm and 5mm hex keys, a phillips head screwdriver, a brake barb tool, and a line cutter assuming you have hydraulic brakes. You will also need a 7mm box wrench if you have hydraulic brakes. It’s a good idea to have a few spare shifter cables and cable ends because you can’t reuse the ones you are cutting. If you try they just end up a frayed mess. If you have hydraulic brakes you will also need a spare barb and olive. Barb and olives are specific to each manufacturer. The ones I linked are Shimano.

There is no right or wrong length when it comes to your cockpit cables. Your handlebars should be able to rotate about 90-180 degrees before the cables get tight. Some frames have a steering limiter in them stopping them at about 90 degrees in order to save the top tube from brake and shifter lever impact.

Start with the shift cable assuming it needs to be done. Use 4mm hex key to loosen the cable are the derailleur, and use the cable snips to cut the cable end off. Pull the housing out of the shift pod to expose the wire, and then pull the wire full out of the housing. From there remove the cable ferrule from the housing. Trim the housing with the cable snips. Before you cut it hold the housing in place on the shifter were you want to cut it to be sure it will work by spinning the bars etc. Once it’s cut, put the ferrule back on. You need to remove the wire from the shift pod. You will either remove a plug with the screwdriver to expose the end of the cable(Shimano), or you will remove the bottom cover of the shifter(SRAM). Run the fresh cable in the opposite way you took it out replacing the plug or cover when necessary. Feed the cable through the housing, and anchor it back on the derailleur with the 4mm hex. Trim the wire after it’s anchored to about two inches. Finally crimp a cable end on the cable to keep it from fraying. I use a small vice grip for this task because they easy and effective. Some of the cable snips also have a built in cable crimper.

Next will be the dropper cable. A lot of the steps will be the same or similar as the shifter cable. The dropper post cable end will either be at the bottom of the seatpost or at the lever. I prefer the ones that are at the bottom of the post because anchoring the cut cable to the lever is easier. First thing you want to do it loosen the cable pinch bolt. It will probably be a 3mm hex key. Pull the housing out of the lever. Don’t worry about the little bit of wire that sticking out. Measure and cut the housing with the cable inside of it. The snips will cleanly cut through both. Remember the move or replace the cable ferrule onto the newly trimmed end. Now the cable needs to be replaced. Loosen the seatpost collar with a 4 or 5 mm hex key. Pull the seatpost out as you are feeding the housing with it. You do this so the end of the housing comes out with the seatpost. Remove the old cable, and replace it with a fresh one. Some posts have a little metal bit that the cable end feeds through with that anchoring to the post. On others the cable end anchors to the post. Feed the cable through the housing. At this point the housing isn’t seater in the lever. Connect the post the cable . Double check ferrules and cables to be sure everything is seated and tight. Feed the post back into the frame slowly working the housing back out the frame. You want to keep the post and housing in contact at all times keep the cable connected. Once the post is at the right height snug down the collar. Feed the cable through the lever making sure you don’t push any cable back towards the seatpost. Pull it tight, and tighten the pinch bolt. Trim and cap the cable the same as above.

Trimming brake lines to be continued in next section.

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Here’s why…..because it’s a budget bike that most riders would want to ride. It’s built with price conscience parts that are good quality. It’s a really impressive bike for under $2000.

Calibre Bossnut

Trimming brake lines

. For this section I am only going to talk about hydraulic brakes. Cable actuated brakes will be very similar to the shifter cable process outlined above with the exception of a few details.

At some point or another you will need to cut a hydraulic brake line to either get it in/out of a frame, or to trim some length off. The process is basically the same for both. The big disclaimer here is that you may end up needing to bleed your brakes when you are done. A lot of the time a simple lever bleed works. I will get into bleeding in another issue.

Some brakes use mineral oil, and others use DOT fluid. DOT fluid is pretty nasty stuff. Gloves and eye protection when working on those brakes is a good idea. Mineral oil is basically harmless. Manufacturers are moving away from DOT fluid for this reason. 2025 will bring a lot more mineral oil options.

You will need your workstand, cable snips, brake barb tool, olives, barbs, a rag and isopropyl alcohol. Details matter here. Order of operations is important. If you make a mistake, you might have to cut more brake line to fix it. There is a rubber cover over the fixture where the brake line and lever connect. Slide it off the fixture, and slide it down the brake line a bit to get it out of the way. The brake line will be attached via a connecting bolt that pinches the hose by the barb with the olive. Use the cable cutter to cut the line close to the connecting bolt. It’s a good idea to have the brake lever either lever or pointed up. Measure and trim the line. The first step in putting everything back together is making sure the rubber cover from above is still on the brake line. Next slide the connecting nut on, then the olive. Use the barb tool to press the barb into the end of the line. Use the 7mm wrench to remove the old connecting bolt. Take the barbed end of the brake hose and insert it into the brake lever. Slide the olive and connecting bolt down. It should be the olive followed by the connecting bolt. Thread the connecting bolt on by hand while you are keeping the line firmly in the lever. Finish it with the 7mm wrench. Finally slide the rubber cover back on. The alcohol can be used for any clean up.