Know Your Drivetrain

A couple of weeks ago, the worst part of winter, spring, arrived. I passionately love bicycling in summer. I think that bicycling in winter is ok. I think that bicycling in autumn and spring often tends to be crappy. Unfortunately, summer here in Finland only lasts for some three weeks, and the rest of the year it is either winter, spring or autumn, but mostly winter. Probably I should also mention that in Finland, a year goes on and on for some 200 weeks, unlike in the civilized countries.

The last winter was so bad that the drivetrain of my trusty commuter got totally fed up with the sucky conditions, and the chain started jumping really bad on the cogs. The jumping got so bad that I had severe trouble going up hills, because when I put any power to the pedals the chain immediately jumped. I tell you, it's hard going up hills on will power alone.

Due to the jumping of the chain, and the resulting slipping of feet on the pedals, the pride of the whole extended family, my precious family jewels, were severely endangered. If it wasn't for the sloping of the frame of my bicycle, I'd already be singing in the same register as Geddy Lee of Rush. While it's a scientific fact that falling on the top tube instantaneously transposes the vocal range of a male a couple of octaves, I suspect that it doesn't have a similar turbo boost effect on one's musicality, composition skills or the ability to perform in front of an audience. Therefore I'm happy to announce that I only fell on the top tube a couple of times this winter, my vocal range is still considered normal and I'm not intending to turn into a professional progressive metal singer in the near future.

Anyhow, like any IT professional would, I considered Getting Something Done about the Drivetrain as a Service (GSDatDaaS, as they say in the bicycling IT nerd world), but then I got to my senses and set out to DIM (Do It Myself). Once again, I spent countless hours (that the employer would consider theirs) doing online investigation of the inner workings of bicycle components and comparing prices.

As you would expect, or possibly not, renewing your drivetrain is not as simple as one would expect. What the hell did I just write there? Does this make sense to you? Erm, anyway, there's a lot of things you need to know:

• how many chainrings do you have?
• how many rear cassette cogs do you have?
• what brand are they?
• what kind of a chain goes together with them?
• how many teeth do your chainrings and cogs have?
  
• what kind of a crank/bottom bracket interface do you have?
• what is the BCD of your chainrings?
• what is the length of your cranks?
  
• what is the chainline of your bicycle?
• etc.

So, the first step was to read about these things. I came to the conclusion that you've got to replace a worn chain and cassette at the same time, and as the chainrings seemed worn too (except the granny ring), it's better to replace them as well.

The second step was to inspect my bicycle in order to find out what kind of a setup I had (underneath all the grimy black stuff). My commuter is a 2008 Kona Dew Plus, and these are the parts that it had installed:

• FSA Dyna Drive CK-300A 175 mm cranks with square taper interface
  
• FSA 28-38-48 tooth chainrings with 104/64 mm BCD
• Shimano 11-34 tooth 8 speed cassette
• KMC Z narrow chain.
  

The third step was to try and find a somewhat similar set of components from an online store. It proved somewhat difficult. For instance, there are a lot of chainrings sold separately, but it's not clear for an aged newbie like me whether or not they fit together with the setup that you have. Also it seems to be cheaper to purchase a whole crankset instead of three separate chainrings. Shimano has all kinds of fancy letter combinations like IG, HG, SG-X and whatnot when it comes to chains and toothings, and they haven't exactly made the whole intercompatibility issue totally clear in their documents. I'm an engineer and I need a detailed specification before I can proceed with the implementation.

After a lot of browsing of internet retailers' web sites, I finally got fed up and ordered a crankset, cassette and a chain that seemed not totally unlike my old components. I failed to notice a nearly unnoticeable text (font size 'fly dropping') saying that the cassette I wanted wasn't in stock though, and I had to replace the cassette with another one. Luckily, there were no other 8 speed cassettes with 11-34 toothing available, and I ended up thinking about the question that has been plaguing mankind for decades: what gear ratios should I have?

I, for one, currently have too many gear ratios. I have a triple chainring, but I never use the smallest chainring. I use the middle one in the winter and I use the big one in the summer. Living in a flat city in a flat country, I don't need more than two chainrings. On the rear cassette, I've never used the 34. Budget cyclist's 34 was as clean as a whistle. I've never used the 11 either. According to Sheldon Brown's Online Gear Calculator, spinning at the moderate cadence of 80 RPM I'd be doing some 46.8 KPH on the 48-11 combination. I hardly ever need to do that on the commuter bike. I guess that on an average commute I use two or three different gears. Ok, in the winter I might use four.

So, what's the point in having 8 speeds in your rear cassette? Or 9, 10 or 11, when you think about it? I suppose that the different ratios are useful only if they're at the range that you need. And I don't need a "MegaRange" 34 tooth cog for anything. I might need more ratios for commuting if they'd be closer to each other. So, I ended up ordering a "road" cassette with 13-26 toothing instead of the one the good people at Kona had originally provided for my needs.

After some minor mixups, awkward speaking of English on the phone (I suck at that) and waiting for some 3-14 business days, the components finally arrived, and I got to the fourth step: actually installing the parts.

Here are the cranksets, new and old:


Look kind of similar, don't they? Yes, I managed to find a crankset with the same toothing and BCD's, but I neglected to read about the chainline. It turned out that the new crankset had a different chainline than the old one, and I wasn't sure how it work together with the front derailleur (or derailer, if you prefer the vulgar spelling).

But then, because I'm a genius, I realised that I can switch the chainrings from the new crankset to the old one. Damn, I'm good. *cough* *retch* I'm choking in my own smugness here. *cough*

Here are the cranks (interesting, isn't it):


Actually, I don't know if the new cranks would have a better chainline than the old one. I gather it's kind of difficult to actually measure the chainline. But I'll have to check it out, when I have the time. Also I could get rid of the granny ring altogether while I'm at it.

Here are the cassettes, new and old:


The 34 does look ridiculously large. It might make sense to grannies though. I, however, tend to fall over if my speed goes below 15 KPH. Also, if you have a magnifying glass, check out the worn teeth on the 4th cog.

BTW, this is what my working area looks like:


I couldn't fit any more of the area into the picture, because my back was against the wall as it is. Well, at least I can reach all the tools without moving my feet. It would be nice if the bike fitted in as well, though.

And finally, what can I say, except "up yours"!