Chain Repair

A broken link

Ever since I became confident about my ability to fix punctures on the road (read about it here), I have been thinking about getting a grip over this problem of fixing broken chains as a next DIY thing to learn. A broken chain on a road trip can stop you and force you to walk to the nearest repair shop or home (whichever is nearer). I started watching a lot of chain fixing videos on youtube. What I learnt is this - you either carry a "missing link" in your saddle bag or you learn how to repair a chain for a temporary fix. Even if you carry a missing link, you must know how to break a broken link. I realised that I have a basic tool with me to break and repair a chain in the form of a Crankbrothers Multi Tool 19. So all I need is some practice. Breaking a link is also an important skill to learn. I do not want to do something on the road for the first time. It just does not work. Before starting to drive on my own, I learnt how to replace a flat tyre and put the spare wheel on. I did it several times at home and then one fine day I had to do it on the road and I was pretty much prepared for it. It was the same for puncture too. It has to be the same for chain repair too. I know a broken chain is a very remote kind of possibility. But no harm in learning a new thing. Baba would have approved of it.

This morning, I stopped near a cycle repair shop in Kalighat and bought for myself an old, rusty discarded chain. They charged me a royal Rs 30 for it, which is a good investment to make if one wants to learn how to break and repair a chain. Incidentally, if you are new to the subject - breaking a chain link is an important part of repairing it. 

First was the dirty job of cleaning the old chain. I don't think it has ever been cleaned during its long life, perhaps pulling a cycle rickshaw. I soaked it in kerosene for about four hours - brushed with an old toothbrush and then washed it in detergent water. Nothing much happened except that both the kerosene and the soap water turned opaque black. Finally, I used some IceToolz degreaser and the gunk somewhat went away. 

I managed to learn quite a few things about chain fixing. But before that let me explain a few things. A bicycle chain is a series of male and female links attached by pins - somewhat like a rivet. In the picture above (on the green table cloth) you can see one male with two females attached to either side. The male remains outside and the females remain inside, so to speak.

Usually it is the male part that breaks under stress. When that happens you have half of a broken male link on either end of the snapped chain attached by two pins. You break those two pins which keep the broken bits attached to the females. Now, you have one less male link. You take out the spare "missing link" from your saddle bag and attach it to the two females. It is a relatively easy thing to do. I don't have a missing link. But if I had it, it should not be much of a problem.

In case you don't have a missing link with you there is a way out. It is not a permanent fix but enough to take you home pedalling. On one side you break the male along with a female but you take care not to push the connecting pin entirely out of the link. On the other side just break the broken male part out. So now you have a blank female on one end and a half open male on the other end with the pin attached to one side (see the picture to the left). What you need to do is connect the female with this male, align the holes and the pin in one line and push the half taken out pin in. What I learnt is that the Crankbrothers tool is not capable of doing this last part. At least not on this chain that I was experimenting with. Because the part of the pin that is protruding out is a micron longer than there is space on the tool. This point will not be clear without a video or without you actually trying to do it. To do this one would perhaps need a dedicated chain breaking tool. Even if you carry a chain breaking tool and can do the job, the chain that you get will be one link shorter. There is yet another option. Carry a portion of the chain in your saddle bag and cut out a part of it and put it in your broken chain. But my cycle has the OE chain and I do not have any spare length of chain. Might as well carry a new replacement chain with a link.

I think the easiest thing to do is to carry a few spare missing links. I am yet to buy them but I will. If you are novice and reading this, please remember one thing - these days there are different types of chains with different sizes. You have to know the type of chain you have and carry the missing link that will fit your size of chain. The chain size depends on the gear speed of your cycle. There is a yet different type of chain called half links. They are totally different and used in BMX cycles. They don't have male and female links. 

What all did I learn today ?

Aligning the tool is critical

1. Aligning the chain breaking tool's piston with the pin to break it is critically important. It is not easy to do this precise alignment. It will take some time and practice to do it like an expert. There are two teeth or cogs on the unit (which also double up as spoke tightening wrenches). You have to position the link in such a way that the holes are engaged on the cogs or teeth (if you look at the accompanying picture carefully you can see it). If the alignment is not right nothing will move - certainly not the pin. 

2. Pushing the pin out to break a link is a little tough in the beginning but then a cakewalk. It gets slightly tough again when it is about to move out of the link. If you want to reuse the pin you have to learn where to stop. If you over push it then you are jacked. Don't expect it can be pushed back a little to compensate for your over pushing. It cannot be. Take my word for it.

3. Pushing a hanging pin back in from the other side using the Crankbrothers multi tool is perhaps not possible. Because the pin length (that is sticking out) is more than there is space to accommodate it. At least this experimental chain that I had was too large. I don't know if my real chain on my Merida has smaller linking pins. It's a matter of a few microns perhaps. But in precision engineered products like chain links and Crankbrothers Multi Tool, such microns make a hell of a lot of difference. 

4. If you push a pin even a fraction of a millimetre in, the link will get stiff. It is possible that this happened with me because I was using a very old chain. But I wouldn't take chances with my real chain. 

5. Cleaning a dirty chain off the bike is not easy. Handling the chain itself is quite difficult as it is totally inflexible when it comes to sideways movement. And kerosene does not work too well at all. Using a  good quality degreaser is far better, quick and effective. Unless you have used a degreaser you don't know how bad and useless and dirty and stinky kerosene is. 

Further Learnings on July 3, 2018

After wasting an entire evening watching a boring world cup match between Sweden and Switzerland I decided to destress myself by once again taking up the old chain and see if it is possible to repair the link with my multi-tool. What I learnt is that yes, it is possible. So I stand corrected. The Crankbrothers 19 multitool is quite capable of repairing a chain by half breaking it.

I had, a few days ago, sprayed the old chain liberally with WD 40. Today I half broke a link - pushing the pin just a bit out and then wriggled the male out. After this I rejoined it. It worked more or less smoothly. As shown on youtube channels. Therefore I can do it. Yaaaaaay.

Two things worked in my favour. A little experience. I think last time I had pushed the pin too far out. This time I pushed it a little less. One has to learn from experience by looking at the pushed out pin and decide. Also with liberal WD40 the pin was much smoother to come out and go back in. After the repair the link seemed a little tight. Exactly as shown on youtube. I pulled it back and forth and it became flexible again.

Doing this at home is one thing and doing it on the street, with the chain on the bike is quite another. But at least I have some practice, albeit at home. Something is better than nothing. But one has to remember that this is a temporary, emergency fix. The particular link that is repaired becomes a weak link. The chain must be replaced immediately after the road side emergency is over.