During May I wrote up some of the tricky bits of my home-build Cinelli Saetta/Centaur 10-speed. You can review these posts in the May archive.
Since I originally put the bike together I've managed around 1,200 miles which is plenty of time to discover most of the issues with the Centaur groupset. Before this build I was using an ageing set of Shimano 105 9-speed kit. Comparisons across Shimano and Campagnolo can get emotional at the best of times and the developments over the last 10 years would make it a bit meaningless. But moving from 9-speed to 10-speed certainly requires a significant step forward in the precision required during the build.
The 'H' Screw
The Campagnolo instructions for the rear derailleur contain a section on adjusting the 'H' screw. Out of the box mine was a bit tight, the gap to the largest sprocket - 25T - was less than the required 7mm. Measuring and adjusting this is a bit tricky, I recommend cutting a 7mm piece of card similar to the one I used when determining the length of the chain.
If you don't get this one right then the chain will need to turn too tightly as it feeds from the upper jockey-wheel of the derailleur to the sprocket. The result is a noisy drivetrain.
Vertical Derailleur Alignment
Despite getting the 'H' screw right I was still having difficulty getting the drivetrain to run as smoothly as I would like. I suspected a problem with derailleur alignment but I rode the first 500 miles trying to find just the right combination of cable tension, 'B' and 'G' screw positions.
I finally realised the something needed to be done when I heard a strange ticking from the chain when I was in the smallest sprocket. After a bit of detective work I realised that this was the sound of the joining rivet striking the inner face of the derailleur hanger. It is a bit hard to visualise but I've done my best to take some pictures:
I've circled the special joining rivet in the two pictures which show that it protrudes enough to strike the hanger.
The first thing I did was adjust the 'B' screw on the assumption that the derailleur must be moving too far out when on the smallest sprocket but even the smallest change resulted in a poor change on to this sprocket.
I also wondered if I had really got this chain joined correctly. I was careful to measure the protrusion on the inner plate with a micrometer to ensure it was as close to the designated 0.1mm as I could get it. This results in a larger protrusion on the outer face of the chain. This is all according to the instructions - the following picture shows this protrusion:
The chain manual comes with the following warning, which makes it pretty clear that I shouldn't consider altering the chain:
The slight protrusion (X) (towards the external side of the chain) of the small pin (E) from the link (Fig. 17) is entirely normal and does not obstruct normal chain movement. NEVER try to eliminate this protrusion.
By a process of elimination the problem must lie with the alignment of the hanger itself. In my 9-speed 105 days I could get things running smoothly again with a simple running repair - aligning the cage by eye while being careful not to actually bend the cage itself. With the Centaur 10-speed this is no longer an option. It is very hard to spot when the cage is off by a small amount but it makes all the difference.
So I stumped up for a proper alignment tool from Park. This really is a good tool, easy to use and really solid feeling. Unlike the comically aligned derailleur on the Park Took help page mine was a bit out of true on the vertical and a bit twisted - this was a brand new frame with a separate hanger but I guess these things are easily damaged in transit or simply don't come straight in the first place.
Correcting these faults and readjusting the gears resulted in that smooth as silk feeling you'd expect from £500+ groupset.
I did have just a couple of other niggles during my first 1000 miles with the Centaur groupset. At one point, during a bumpy descent, the cable tension on the rear derailleur seemed to go completely wrong. I ended up fiddling with the barrel adjuster on the road but I couldn't get it right again.
It took me ages to notice that what had happened was that the brifter had a slipped a tiny amount on the bar. The cables where taped firmly to the bar under the handlebar tape so the result was that the tension increased a little on the cable as a tiny gap had opened between the end of the cable cover and the cable stop in the base of the brifter (all unseen under the covers).
The final issue I've had seemed to be heat related. England had a particularly cool (and rainy) spring/summer but the hot weather has finally arrived now and this seems to have been responsible for a few problems with increased friction between the gear cables and the plastic cable guides on the frame. It may just have been the grease drying out too quickly or perhaps the heat softened the plastic a bit and allowed the cable to cut in a little. Either way, the problem was fixed by slackening off the cable and re-greasing.
The Centaur 10-speed groupset sounds smooth and the change is nice and crisp. The ability to multi-shift when changing to the larger sprockets is useful, especially after you've just changed up to the big ring. For me, the big selling point is the position and ease of operation. My short fingers can change up a sprocket (or maybe even two) using the Centaur's lever without difficulty even when on the drops. This is a big change for me and for the first few hundred miles I found myself bringing my hands up on to the covers out of habit, the Shimano system of pushing the whole brake lever was always too much of a stretch for me from the drops.
Although some people complain about the position of the button for dropping to the smaller cogs I can reach it from the drops without too much of a stretch. Of course, I did have the luxury of fitting them exactly to my preferences!
On the negative side, the brifters seem a little light and flimsy. Light is a good thing of course and I'm probably just out of date - my 105 levers felt more robust but they also weighed a lot more. On the few times I have had problems with the Centaur gear-change the levers and, in some cases, the shift button have gone very stiff and I felt like I've had to treat them carefully to prevent accidental and expensive damage.
More significantly, the 10-speed drivetrain is very particular about adjustment. The extra sprocket seems to come at the expense of significantly more tinkering time. Although this was a home build project the real fun comes from riding the bike. After 1,200 miles I really seem to have found the sweet spot but it's already time to start checking for chain wear. I'm a light rider riding 165mm cranks in a fairly flat part of the country so hopefully I'll be able to squeeze a few more miles out of the Centaur chain before I need to replace it.