It’s been eight months since I pulled both a hydraulic brake line and Di2 shifter cable through Kuroko’s downtube and attempted to cut out the existing grommets with a knife to accommodate two cables in the place of one. This was just one step in the Shifting to Glide project, but it was a significant one because it meant the longest Di2 cable (950mm, in the end) was routed internally and I didn’t have to tape it to the outside of the frame (which is what we ended up doing for the cable from the junction box below to the crankset to the rear derailleur).
I was sort of able to cram the existing grommet back into the frame at the top of the tube after hacking it away with a knife, but the result was far from aesthetically pleasing — to say nothing of the lack of waterproofing. At the bottom, where the cables exit the frame just ahead of the bottom bracket and hence are most exposed to splashing, I’d given up. The grommet was left dangling there, both cables running through it but not even close to where it was supposed to be plugging a hole in the frame.
I searched quite a while and found some two-holed grommets that seemed the right shape and size, but that was some months ago. I’ve been delayed completing the project by:
- the enormity of the work, which would include redoing the rear brake line and the handlebar tape, and
- the fact I’d lost a part for the tool needed to redo the rear brake line.
A couple of weeks ago I emptied out the storage box on the Workshop in the Sky (for the second time) and found the missing bit: the mandrel for the disc brake hose cut & set tool. So I’ve just been waiting since then for the opportunity to get the work done. The faffing about with tires last week and earlier today was just me trying to avoid biting the bullet on this job.
Starting at the rear
I already had rear wheel out to remove the inner tube and clean up the old tape, so I started at the rear brake. I removed the brake pads and inserted a block to prevent the disc pistons from popping out of place. This would prevent the brake pads from coming into contact with brake fluid as I removed and then replaced the brake line, and subsequently bled the brakes.
(When I installed the hydraulic brakes the first time around, I did it with the brake pads in place with no issue — but I was tempting fate with my naïveté.)
Next I cut off the end of the brake line, with the barb and olive that seal the line when it’s bolted into place, so I could remove the bolt and fit the line through the grommet. Both the hydraulic line and the Di2 shifter cable fit through their separate holes in the grommet easily enough, but the grommet was just a tad too large to squeeze into the opening in the frame. The grommet looks like soft, squeezable rubber, but it’s not. It’s a tough resin with very little give.
So I had no option but to trim the grommet down to size with a craft knife. I’m glad I had on a 3M glove for this part of the process — I’d have cut my fingers more than once otherwise. As I had the protection, the carving up bit went without a hitch, and on the next fitting I was able to push the grommet into the frame with enough force required to make me confident it won’t just pop out the next time I ride over a bump.
Yes, there’s tape
With the rear done, it was time to repeat the process on the front. Before I could get to the brake line, I had to remove the handlebar tape, which meant cutting through some finishing tape and black electrician’s tape and then unwrapping the actual handlebar tape. It came off easily enough.
Ojisan with a wrench
Easily half my anxiety about this job was in the next step: loosening the bolt holding the brake line in the Di2 shifter. During the initial installation, I’d coached as José tightened these bolts to the correct approximate torque. And then the following day, I was looking at the bolts (left and right shifters) and noticed they had flanges, and the flanges were a couple of millimeters shy of fitting snug against the shifters. So against all common sense (and not bothering to take a minute to check for pictures or diagrams on the internet), I took a wrench and tightened the living stew out of those bolts until the flanges were flush.
Some time back, a local bicycle repair shop I follow wrote an impassioned post about the dangers of an ojisan with a wrench after having a number of customers bring in bikes for repair. The customers would say, “I was having a little trouble with the bike, and then an ojisan said he was familiar with bikes and would help me. And now the problem is much bigger.” And after realizing how I’d over-tightened those bolts, I was afraid I was the ojisan with a wrench (not for the first time, I assure you).
After removing the handlebar tape and pulling back the brake hood, I took a wrench to the bolt in question: it loosened readily and gave no signs of having damaged threads. Imagine my relief!
The upper grommet fit in nicely after I’d trimmed it with the craft knife as I’d done for the lower grommet. Then I used the cut & set tool to put a new barb in the brake line, making use of the mandrel whose disappearance had delayed this project.
That done, I sleeved the brake line and Di2 cable together through some heat shrink wrap for a professional finish. Now, I’m not saying I bought a heat gun just for this one job, but I’m not saying I didn’t, either. (I placed an old work glove behind the shrink wrap to protect the Di2 junction box from the heat.) I’m mostly pleased with the result, although I can’t say that every time I ride Kuroko I won’t obsess over that little blip in the place the two pieces of shrink wrap overlap.
With everything back in place, I used electrician’s tape to secure the lines to the handlebars again. With the changes in the brake line length, the re-taping and the heat shrink, the brake line interfered with the clapper for the bell. After sweating this out for a moment, I rotated the bell so the clapper was clear of the brake line. (I prefer this more horizontal arrangement. The position of the brake line previously prevented the bell ringing when the clapper was in this position. So it’s a win.)
Bleeding to death
I rewrapped the handlebar tape next. I was a bit worried the tape would have lost its sticky power with the unwrapping, but it went fine. I’ve got electrician’s black tape holding it at the top now instead of the decorative tape, but I can live with that.
The final step was to bleed the rear brake. Inevitably, some fluid had dripped out during this job. I got out the bleed kit and topped up the syringe with fresh fluid. It took a bit of time squeezing the brake lever and pressing more hydraulic fluid into the system, but I was soon happy with the result. I tightened the bleed valve on the caliper (not overtightening!) and put the screw back in the brake lever, then removed the block and put the wheel back in the frame.
Happy with that — so far
With the wheel — sans tire — in the bike, I ran through the gears and hit the brake a few times. No problem with the gears at all, while the brake firmed up after one initial pull where nothing happened.
And that’s where things stand now. I’ll have a go at the rear tire tomorrow and (one way or another) take Kuroko for a spin around the block. (It will still be too hot for a full ride.) Here’s hoping I don’t discover any issues on the road that didn’t crop up in the stand.