Today marked our third try at converting Kuroko to electronic shifting, and we made a lot of progress. We’re only held back at this point by the bolts of the rear brake caliper, which refuse to let go.
Clean up your act
While I was waiting for José to appear, I took off the cogs and started scrubbing them. The chain lube I use for wet conditions (i.e., does not rinse away at the first hint of rain) really sticks to the gears and doesn’t want to let go.
Using some degreaser and a lot of elbow grease, I’d cleaned up about half the cogs before José arrived.
Stuck, stuck … stuck
The first order of business was to remove the rear brake caliper, which has been frozen in place from the beginning of the project. We tried a second set of bolt extractors to no avail, and then some drill bits (same). We just weren’t getting a bite into the metal.
The upgrade project was blocked at this point: the Di2 shifters have hydraulic brakes, so we have to get the old, cable-operated, calipers off the bike. Despite this set-back, I was determined to get as much done today as we could. In particular, I wanted to see the derailleurs in operation.
The next order of business was to wire up the battery, shifters and derailleurs. Following the debacle of short connection cables last weekend, I’d ordered up some longer Di2 wiring. We quickly pulled a new cable through the downtube to connect the front junction box to the rear, and replaced the shifter wires with slightly longer bits.
I’d got a battery mount to sit below the water bottle mount, and that went on with a minimum of fuss. The remaining bit was the cable for the rear derailleur. There are ports in the chainstay to run a cable internally, but we quickly determined that there is not enough clearance for the Di2 connectors to pass through. We had to settle for external routing of the rear derailleur cable. Fortunately, I’d thought ahead (for a change) and bought the cable guides to stick the cable to the bottom of the chainstay.
And … magic!
I was half expecting the derailleurs not to work right out of the box — partly because I’d cobbled together this solution from disparate sellers (although it’s all Shimano in the end) and partly because this was my first experience of electronic shifting. But in fact the moment it was all wired up … the shifting worked!
It was a few minutes’ work after that to put the cogs (half cleaned, half greasy) back on the rear wheel, and put that back on the bike. Then cut the new chain to length and adjust the derailleurs. It all went well apart from pressing the pin into the new chain to fit the length. We got the pin only partially in at first, and in the process bent one of the links. It’s working OK now, but I’ll probably get a couple of replacement pins and swap out that link (and its neighbours) before taking this show on the road.
Stop in the name of love
With the derailleurs settled in as well as can be expected, we turned our attention to the front brake caliper — the one we could do something about. It was easy enough to attach the new caliper to the fork, and I quickly determined we had the right orientation. (There’s a reversible bracket which allows for different diameter brake discs.)
After that it was all new to me. I’ve seen a number of videos on bleeding hydraulic brakes, although they tend to be generic rather than focusing on specific models, and I’ve heard the horror stories of hydraulic brakes gone wrong. We had our share of reversals and false starts, considering this is all new to us, but in the end we got there. The instructions didn’t specify which retaining bolt went into the brake levers and which into the calipers (and they are different), so I got that wrong on the first go but sorted it on the second try. (There weren’t any other options … )
When it came time to add the brake fluid and bleed the system, it turned out the reservoir cup from the first system I’d ordered was the wrong size. But the second set had the right item, and it all came together. Again, considering this was something I’d never done before, it went quite smoothly. We had just a minimum amount of brake fluid scattered about the workshop, but in less time that it takes to tell, I had a working front brake!
Compared to the cable-operated disc brakes that came with Kuroko from the factory, these are much easier to apply, much smoother, and have a lot more power. I’ve often read that hydraulic brakes are superior to cable, but this was my first experience. I can only say that the reports I’ve read don’t tell the full story — get hydraulic brakes!
Where do we go from here?
The only sticking point now is the rear brake caliper, held on by rounded-off, drilled-out bolts (as it has been from the start). It’s a cable-operated caliper, and so not compatible with the Shimano GRX levers, which are hydraulic. We’ve failed to remove the bolts using extractors and drill bits. I tried a hacksaw today, but after a couple of minutes it became clear I was removing as much material from the frame (a no-no) as the caliper and its retaining bolts.
Next weekend I’ll chuck the bike into the back of a car and take it to the workshop at my office. There I can try a high-powered drill, a grinder … whatever it takes. If I can’t get satisfaction there, maybe it’s time to replace the frameset as well.
Assuming I succeed in removing the brake caliper (at last!), all that remains is to install and bleed the new caliper, tape up the handlebars and (pièce de résistance) add the new saddle.