2014 Giant TCX full cable replacement, part 3: Shift cable housings

In this final installment of the full cable replacement series, we’re going over shift cable routing.

The process has actually been mostly covered in previous posts, and part 2 of the series has a guide to threading the cable housings through the downtube. I’ll be discussing only the areas where there is most difference from the rear brake cable replacement job.

In the photo above, the two shift cable housings actually share one cable routing hole, unlike the brake cable housing which has its own, off to the side. Making matters worse, this is a tight fit. I had difficulty with fitting the Park Tool IR-1’s guide cable magnet ends through this hole while it still contained one cable housing, and is otherwise still hooked up to the relevant derailleur via the inner cable.

This is why I recommend replacing the downtube-routed shift cable housings at the same time. While the shift cable housings are empty of a shift cable, you can play and finagle with them so that the IR-1 guide cables can thread into the downtube properly.

Above are the shift cable housing segments. The long segment runs through the downtube, joining the in-line barrel adjuster floating around the head tube area and the relevant cable stops. It is pretty much the same length for both front and rear derailleur, since they all terminate around the bottom bracket shell area.

At the bottom of the downtube, both shift cable housings also share the same cable routing hole.

Thread the housing segments one by one through the downtube, and hold off on the shift cables until they are both routed cleanly through.

Here’s the result. The cable housing in the background arcs backward toward the rear side of the seat tube, where a cable stop awaits for the front derailleur. The cable housing in the foreground feeds into the drive-side chainstay, where a different cable stop awaits…one with a cable liner in it. Both these cable housings need ferrules on their ends.

 

Crank arm set parallel to the downtube. All the cable housings exit the downtube and loop over the bottom bracket shell before continuing to their destinations. Sandwiched between the seat tube and the rear fender is the cable stop for the front derailleur.

As before, once the shift cable housings are correctly routed, the replacement job is 90% complete. All that’s left is to complete the rest of the rear shift inner cable routing, hook up STI levers with derailleurs, and tune properly.

2014 Giant TCX full cable replacement, part 2: Brake cables and housings

Tools, check. Supplies, check. Now on to the nitty-gritty of actually replacing the cables.

FRONT BRAKE CABLE REPLACEMENT

Let’s start with the front brake, since that’s the easiest as it’s a fully external run. If you run a front fender like I do, start off by removing that.

Giant uses a plastic retaining clip to keep the front brake cable out of the way, held in place on the underside of the fork by a small 3 mm hex bolt. Undo that and set it aside.

Remove the bar tape, and clean off any adhesive residue from the handlebar with a wipedown of isopropyl alcohol. Cut open and remove the electrical tape holding the cables fast to the handlebar.

On the Spyre brake caliper, snip off the cable end cap, then undo the clamp bolt. On the Shimano 105 ST-5700 STI lever, pull the brake lever, work the brake inner cable head out of its seat, then pull it straight out.

With the inner cable out, it’s just a matter of undoing the front brake cable housing. On my bike, this is also the only segment of housing that doesn’t have an in-line barrel adjuster, making replacement straightforward.

Lay out old housing against new, and use it as a guide for measuring the proper length.

5 mm brake ferrule. Jagwire’s POP ferrules have an additional piece that goes between this and the cable housing end.

Cut the new housing. Because the end can get a little squished by the cable cutters, I like to round out the liner of the freshly cut end so the brake inner cable can enter smoothly. Once done, cap one end with a 5 mm brake ferrule; this end goes into the brake caliper. (Jagwire includes a pack of two-part “POP” brake ferrules with their compressionless brake housings.) The other end with no ferrule goes into the 105 STI lever.

At this point, you’ll want to have the fresh brake inner cable ready. Shimano’s retail brake cable kits include enough brake inner cable and spiral-wound housing for one front brake (the shorter one) and one rear brake (the longer one), plus two chromed ferrules and end caps. As Hyro has TRP Spyre calipers, we’re not interested in Shimano’s brake housing; all we need are the brake inner cables and end caps.

 

With the front brake cable housing hooked up, thread the new brake inner cable through the STI lever the same way it came out. Push it in and pull it through until it is fully seated.

 

At the front brake caliper, wind in the barrel adjuster all the way by turning clockwise, then back it out two full turns to leave some room for adjustment. Pull tight on the brake inner cable, pre-load the actuator arm, then tighten the cable clamp bolt. Put the cable end cap on to keep it from fraying and injuring others.

Job done.

REAR BRAKE CABLE REPLACEMENT

Compared to the front brake, cable replacement for the rear brake is more involved. The cable enters on the left side of the downtube, reemerging at the bottom bracket shell and going around it, then finally threading through the left chainstay, where it pops out just in front of the rear brake caliper. In addition, there are four rubber grommets that the brake cable housing runs through as it pops in and out of the frame tubes while bridging STI lever and brake caliper.

I highly recommend the Park Tool IR-1 internal cable routing kit for this job. Some patience is also required, as the compressionless brake housing’s reluctance to bend can make clearing the entry and exit holes a bit of a challenge.

We start the same way as before: Undo the cable clamp bolt at the rear Spyre brake caliper, remove the cable end cap, then remove the rear brake inner cable clear of the bike by pulling it out of the STI lever. From here on out, we’re mostly concerned with the brake cable housing and getting it to where it should be.

First we will have to take care of the four rubber grommets along the run of brake cable housing. Two of them are rectangular, and have to be pried open and away from the frame, either by finger or with a flat head screwdriver. One lives on the inside of the left chainstay in front of the caliper, and the other lives underneath the downtube. On these rectangular grommets, the cable housing has to be threaded through them.

The brake cable here is in the foreground. The other length of housing in the background, closer to the chainrings, is for the rear derailleur.

The other type of rubber grommet is oval. The underside is in two halves, so the grommet basically wraps around the cable housing while being held in place by the relevant routing holes in the frame. These are on the left of the downtube and on the underside of the left chainstay, near the bottom bracket shell. Once they’re off the routing holes, they can be detached from the housing.

Two lengths of old compressionless brake housing interrupted by an in-line barrel adjuster.

Once all the grommets are off and the old brake cable housings pulled from the frame, here’s what you get. That long piece is an uninterrupted run from brake caliper through chainstay and downtube, all the way to the in-line barrel adjuster.

The two shorter pieces on the right run from the barrel adjuster to the STI lever, and technically can be replaced by one single piece of compressionless brake housing. The silvery piece is from an old Jagwire cable kit, called an “EZ-Bend” housing segment. It acts as an extra-long brake ferrule and handles the cable run underneath the bar tape.

At this point, we break out the IR-1. Of its three guide cables, we’ll need the one with the threaded barb, which we screw into the end of the cable housing. Screw it in as far as it will go.

Drop the magnet end of the guide cable into the cable routing hole at the left side of the downtube. Once it’s in, chase it with the guide magnet from the outside of the downtube until it gets attracted.

From there, it’s a matter of feeding the guide cable in and pulling the guide magnet along the outside of the downtube, until it emerges from the cable routing hole.

Pull the guide cable all the way through, and it should drag the new brake cable housing along with it, emerging from the bottom of the downtube. At this point, you can go ahead and thread the housing through the rectangular grommet and reinstall it into the routing hole on the downtube.

Two more routing holes to go, this time through the non-drive side chainstay. The same trick with the guide cable and guide magnet applies here, though. Take your time and be patient.

This final cable routing hole is the biggest challenge. The guide cable is very flexible and can clear it with no issues…

…but the much stiffer compressionless brake cable housing will require a bit of persuasion to come out. This is where inserting the threaded barb into the brake housing as far as it will go will help a lot.

Once all the brake housing is correctly routed through the frame, you’re 90% done. Thread the housing through the remaining rectangular grommet, and wrap the housing with the oval grommets and push them into their relevant routing holes.

Connect all the housing segments and barrel adjuster into a continuous line as you push the rear brake inner cable into the STI lever, then hook up the inner cable into the Spyre’s actuation arm. Tune and adjust the cable properly, and that’s job done.

In the final installment, we will look into the shift cable routing.

2014 Giant TCX full cable replacement, part 1: Preparation

In the past, I’ve written about the internal cable routing of Hyro, my 2014 Giant TCX SLR 2 cyclocross bike, as well as walked you through a rear shift cable replacement. However, I’ve never been able to give him a completely fresh set of cables and cable housings. Three and a half years in, he’s been long overdue.

One major reason was simply gathering the supplies and tools needed for the job.

If you’re even thinking of doing this job on your own, invest in a proper dedicated set of cable cutters. Unlike pliers, which can crush cables and housing, these will give you clean cuts by shearing action. I’m using Park Tool’s classic CN-10, which is highly recommended by a lot of mechanics. Jagwire, Pedro’s, Super B, PRO, and other tool makers have their own versions which should work just as well.

Park Tool’s guide to the different types of cable housing, with a cross section of each.

As great as TRP’s Spyre mechanical disc brake calipers are, they explicitly state that they work best with compressionless brake housing. Unlike traditional brake housing, which is spiral coiled along its length, the compressionless stuff more closely resembles shift housing in that it is made of multiple small wires in parallel that surround a plastic inner liner. In many varieties, what makes it compressionless is a woven layer of aramid fibers surrounding the whole thing. (One aramid variant is Kevlar, famously used in bulletproof vests.) This means compressionless brake housing is more resistant to bending, and must be routed as cleanly and with as few abrupt bends as possible.

There are Jagwire full cabling kits that carry their compressionless brake housing. However, they’re way too short for the full-length housing run required on many cyclocross bikes, and I don’t know any local bike shops that carry the “XL” version of these cabling kits – that would’ve worked.

Internally routed cables in a bike frame are a common bugbear of bike shop mechanics. There are many hacks out there that can help decrease the time sink and aggravation of fishing out cables and housing from inside a frame tube…but I say investing in a Park Tool IR-1 internal cable routing kit is the ultimate hack of all. I will be talking more about this tool in the future, but suffice it to say that it is AWESOME.

The final requirement is a set of ferrules, one each for 4 mm (shift cables) and 5 mm (brake cables). These are essentially caps that slip over the ends of the cable housings to prevent them from mushrooming outward. While brake ferrules can be made of plastic, shift ferrules are typically made of metal. On the 2014 Giant TCX, you will need six shift ferrules and four brake ferrules in total, and not all housing ends require them.

As you’ve no doubt picked up by now, preparation is crucial. I doubled up on it by buying shift cables, shift cable housing, and brake cable housing in bulk. I also have a couple road brake cable sets bought as spares. All that shift inner cable and cable housing should last me a few years; all I’ll have to replenish are brake cables and relevant ferrules when my supply runs low.

Finally, since full cable replacement involves removal of your handlebar tape, you might as well have a new roll of the stuff on hand. In a break from tradition, I tried Fabric’s knurl tape this time around.

In the next installment, I will walk you through the brake cable replacement.