The problem that prompted me to try this in the first place was imprecise front chain ring shifting. If I tried to shift from the smaller chain ring to the larger (for going faster) I would need to keep the shifting lever pressed while still pedalling. Otherwise the chain wouldn't climb the bigger ring. Also when going down from the larger one to the smaller there were two clicks that were happening.
I had lubed the front derailleur last night in the hope that that was possibly the issue but it didn't help matters much. Today I wanted to tweak the tension in the cable. But before doing that I spoke to Someswar. He agreed that that was probably the cause and gave me the confidence to go ahead. He told me specifically not to play with the limit screws. Someswar is a knowledgable mechanic who I trust.
Now the problem with this cable in my bike is that it is in a place where turning the hex wrench is difficult because the rear wheel is there. I used the smaller arm of the L hex wrench to loosen it. The cable suddenly came out, as if it snapped. I pulled it up with my hand and tightened the nut. Checked the shifting. Now it has become much worse. The chain just wouldn't go to the larger ring. It kept going back to the smaller chain ring. I realised that probably I had made the cable even more loose.
Now, I used the 4th hand. It is meant for precisely this kind of applications. It's a special type of pliers that holds a pulled cable in its place when you tighten the nut. But using it itself is a challenge if you don't use it regularly. Somehow solved this challenge and then tightened the nut. Voila. The chain shifts perfectly now. I need not keep the lever pressed.
There was another newbie issue that had to be solved. Between the nut and the surface on which it tightens there is a washer. Now whether the cable stays on this side or the other is something I didn't see when it came out. I did what my intuition told me to do. The flat surface of the nut, washer, cable and then the surface on which the whole thing was tightened. This was the order in which I did it. It's working. Therefore it must be okay.
Barrel Adjuster - On the road last night (today is 26th) for a test ride I found the shifting was fine for the first few times and then it seemed it had gone loose once again. Today instead of pulling the cable up I tightened the cable through the barrel adjuster just a bit. It is working now.
Barrel adjusters are very confusing little bastards. If you loosen them (lefty loosey) they actually tighten the cable and make them shorter. I did just that and it is now working fine. Let me see for how long.
I used this video here . At around 6 minute mark the barrel adjuster adjustment is explained in very easy terms.
Rear Derailleur - Today I also realised that my rear derailleur was also suffering from a slack cable tension. It was not climbing the first gear (largest cog). That's a surefire sign of the cable being loose. I turned the barrel adjuster a quarter turn (or was it two?) and now it's shifting much better and going all the way up. So adjusting cable tension is sorted for now.
8th October 2020
After this initial success with the Roadie, I went ahead and adjusted the tension in my derailleur cables of the Surly. It also had front derailleur problem of a similar nature. You needed to hold the shifter while the chain moved from the smaller to the larger chain ring. After the adjustment it is working much better. Here the shifting is bar end and the barrel adjusters are near the down tube. Quite different from the Roadie.
I have half a mind to change the shifters from the bar end to the downtube. There are braze ons and bosses there meant precisely for this. This change will remove some clutter from the handle bar. Two cables less and it looks like a less complicated system to shift.
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