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Bike chain - John C. Kirk

Apr. 10th, 2011

12:52 am - Bike chain

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I like to think that I'm a fairly good cyclist, but my weak point is bike maintenance. I'm making an effort to improve in that area: it can save me money, and it makes me more self-reliant. For instance, I mentioned Brompton punctures a while back: if it's the rear wheel and I take the bike to Evans then they'll charge me £27.50. Also, if I'm in the middle of nowhere then it may take me a while to push my bike to a repair shop.

More recently, I've been thinking about chains. I had my Brompton serviced in January, and they mentioned that the chain was so stretched that it was literally off the scale, so they replaced it. I've heard people talking about this concept a few times, but I didn't really understand it until I bought a new tool: a Park Tools Chain Checker. You put the pegs between the links of your chain, then slide one end outwards until it hits the chain; this tells you how worn your chain is. In other words, the stretch is "side to side" rather than "end to end", and the chain won't actually get any longer. This stretch is bad because it makes the chain more likely to slip off your sprockets (cog wheels), so it might derail, and apparently it can cause extra wear and tear on your gears. Now that I've got the tool, I can test my chains periodically, and I'll know when to replace them. If you live near me, and you'd like me to check your chain, just let me know.

Meanwhile, my Roberts bike has been making some odd noises recently, to the extent that pedestrians turned around when they heard me coming. It only happened when I was pedalling (rather than freewheeling), which implied that it was a chain problem. The obvious solution is to oil it, but I gather that it's a good idea to clean the chain before you put the lubricant on. Since I'm turning into a bit of a hippie, I bought degreaser and oil from Green Oil. I also bought another Park Tools gizmo: the Cyclone Chain Scrubber. This was something of a mixed success.

If you have a driveway, that would be a good place to clean your bike: you'll have plenty of space, and it won't matter if you make a mess. Unfortunately, I don't; my front door opens directly onto the pavement, so I'd be in the way there. Instead, I put down newspaper on the floor of my flat, which turned out to be more important than I realised.

Ideally, you would use some kind of repair stand to hold your bike in the air while you work on it. That way, you can turn the wheels and pedals while the bike itself stays still. Again, though, I don't have one. My bike has a centre stand (two legs), and I can spin one wheel around while the other one rests on the floor. However, I can't turn the pedals while the bike is on that stand, because they hit the legs. So, I leant the bike against a wall, keeping it as vertical as possible. Meanwhile, the front wheel had an unfortunate tendency to pivot around, so this wasn't very stable. If you live in a multi-bike household, I recommend a reciprocal arrangement, i.e. "you hold my bike up, then I'll lift yours".

The Cyclone gadget looks a bit like a water pistol, and you clamp it around the chain. According to the instructions, you should put the bottom half in place, then pour in the cleaner, then lock in the top half. According to the video on their website, you lock both halves around the chain, then pour in the cleaner. However, Green Oil say that if you use their degreaser in a machine like this (rather than applying it to the chain with a rag) then you should dilute it with 3 parts water. My approach was to fill the bottom half with water (from a tap), roughly 3/4 of the way up to the line they've marked, then put it under the chain, then squirt in degreaser up to the line, then lock the top half in place. The catches require quite a bit of force, so it's fiddly to do that one-handed.

The instructions also say that you should put the chain onto the smallest ring at the back, i.e. the nearest one to you. (The chain is on the right side of the frame, so that's where you need to be.) If you plan ahead, you can use the correct gear while you're cycling; if you don't, you have to lift the bike while spinning the pedals by hand to change gear. My bike has 2 gear wheels at the front, and 9 at the back, which theoretically gives me 18 altogether. However, it's not a good idea to stretch the chain to opposite "corners", e.g. leftmost wheel at the front and rightmost wheel at the back. In fact, I'd say that 2 end wheels at the back are off-limits for either of the front wheels, which gives me a practical limit of 14 gears. Unfortunately, I forgot about this when I was preparing the bike.

Once the Cyclone is in place, the next step is to turn the pedals backwards through 30 revolutions. You can leave the bike wheels on the ground for this, because it won't move the bike. However, this will move the chain, which is the entire point of the exercise: the idea is for it to pass through the scrubber, getting clean. The scrubber is a fairly tight fit around the chain (probably deliberate), so you need to hold it quite tightly, otherwise it will get carried along with the chain and collide with the front gears. So, you use your right hand to pedal, then your left hand to push against the chain movement. The tricky bit is direction, because you don't want to move the chain from side to side. Soon after I started, it derailed at the front, and I then remembered that I was using a "bad combo". This was a bit fiddly to correct: I had to brace my shoulder under the saddle to lift it up, then pedal by hand. If I used one hand to hold the Cyclone, I didn't have a 3rd hand to actually get the chain back onto the front sprocket, so I had to remove the Cyclone temporarily then reattach it afterwards.

Once I'd sorted that out, I found that the chain kept slipping up onto bigger chain rings at the back, and then I wouldn't be able to pedal. Again, this involved lifting and pedalling, using my left hand to hold the Cyclone steady. Remember that I mentioned the newspaper? If the Cyclone tilts then liquid will pour out of one end. Also, the chain will pick up the cleaning fluid on its way through, and then it has a tendency to drip.

I was supposed to do 30 revolutions, but it got stuck after 27, so I figured that would do. Bear in mind that the degreaser is removing any existing lubricant, so it sounds reasonable that it will get harder to move the chain around. On the plus side, I looked at the chain and thought "Wow, that's the colour it's supposed to be!" I don't have a (working) camera, otherwise I would have taken before and after photos, but there really was a visible difference. I noticed a few black hairs stuck in the chain, presumably from the Cyclone's brushes, so I tugged them out.

I removed the Cyclone, and rinsed it out, although it still kept bubbling (like washing up liquid) however much cold water I put through it. Anyway, I reattached that and did a few more backwards pedal revolutions, to rinse off the chain. I then dried the chain using kitchen towel: I put it around the chain, then turned the pedals backwards to run the chain through the towel. I still got a lot of black dirt left on the towels, but after the 3rd towel I decided that it was good enough for now; certainly an improvement on how it was before. All in all, it took me about 45 minutes to do the chain cleaning.

The next step was to oil the chain, and this was a lot quicker. I went to a Dr Bike workshop a while back, where the mechanic demonstrated the technique. Basically, you put one drop of oil on each of the "pegs" that run perpendicular to the chain, holding the links together, then turn the pedals a bit, and keep going until you've done them all. Then you wipe off any residue using kitchen towel (or a rag).

After I've put oil on the chain, it's not obvious (at least to me) which links I've done, so it's useful to have some kind of marker on the chain, e.g. a sticker. In this case, I found something better: one of the links is a SRAM PowerLink. I've read about this recently, but I didn't ask for one when I specced out the bike (since I didn't know about them back then), so I didn't realise that I had one on the chain. Basically, this is a special link that you can unhook, then you can take the entire chain off the bike. Once you've done that, one cleaning method is to fill an empty Coke bottle with cleaning fluid then dump the chain into it (submerging the chain). If I'd known I had that, I might not have bothered with the Cyclone. Ah well, live and learn. The oiling process took about 5 minutes altogether, so it was much quicker than the cleaning.

I haven't done a proper test ride yet, mainly because it's a hassle to carry the bike downstairs. However, I lifted it and did a short pedal, and it sounded better than before, so that bodes well.

My plan for tomorrow is to cycle down to Brighton; hopefully this will go better than last month's attempt, and I'll see how the chain performs.

Edit: The chain performed well today (Sunday), and the bike ran in "Whisper Mode". The only snag is that I left it in top gear after I cleaned it last night, and didn't discover this until I tried to move off from the kerb! Fortunately there was a big gap in traffic, so I had time to shift down.

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[User Picture]
From:totherme
Date:April 21st, 2011 07:28 pm (UTC)
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"chain stretch>" does result in a longer chain.

The individual links don't get longer, and you don't get any more links, but the joints between the chain links do wear down. If you imagine every hole in every chain-link getting a little bigger, this results in the maximum length of two joined links being slightly longer. Imagine joining two links together by aligning their holes and pinning them. Now imagine doing the same thing if each hole is oval-shaped instead of circular, but your pin is still has the old circular cross-section. This also means that the chain has more lateral flex, which is what your tool measures.
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[User Picture]
From:johnckirk
Date:April 22nd, 2011 11:29 am (UTC)
(Link)
Thanks - that's useful to know.

When I went to the Dr Bike session, the mechanic had a chain checking tool like this: no moving parts, so it just gave a "yes/no" answer rather measuring the degree of wear. He put that between the links of the chain, so I assumed that it was basically acting as a ruler to measure the distance between those links.

I came across that Sheldon Brown page more recently, but I didn't really understand it (he's one of the "people talking about it" I referred to in the post). Since he put "stretch" in quotes, I took that to mean that the chain isn't really stretching out.

Anyway, I think I understand it now.
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