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It All Started With a Chainring

Posted: January 15th, 2009 by Karen Brooks

chair_mess.jpg

Some weeks ago I noticed that the large chainring on my cyclocross-style commuting bike was badly and unexpectedly worn – the teeth looked like pointy little shark teeth, rather than the rounded swells they should be. It wasn’t all that old, but it did go through some nasty street slush and muck this past spring.

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So I set out to replace it. The chain was also worn, but fortunately not to the point that it had caused the other chainring and the cogset to assume similarly wrong shapes. Whew. I got a new chainring, but found that the new one, while being very nearly identical, was just a slice of a millimeter or so thinner at the bolt holes. So I went in search of spacers at the local shops. One mechanic graciously spent about 15 minutes searching in basement bins and came up with four of the five I needed. Close enough for now.

Of course, like many errands of this nature, it took me a few days to do this shopping, and in the meantime I had thoroughly cleaned the cranks and bottom bracket, and applied grease where necessary. Since I did all that, I figured I might as well clean the cogset too. At some point during the past six months I had experimented with a vegetable-oil lube, decided I didn’t like it, and switched back to my trusty Boeshield T-9… but I had neglected to clean all of the old lube off of the drivetrain. The resulting paraffin/oil/grime mixture had encrusted itself onto the parts like some sort of evil alien lichen, and needed several more days of soaking in degreaser, plus scrubbing with toothbrushes and rags, to remove.

So while the cogset was off I decided to check out the hub internals. Lots of cleaning and regreasing there too. Next, might as well true up the rear wheel, which meant bringing it into the office. Rather, remembering to bring it in to the office.

It seems the Chris King headset was the only part that barely needed any attention, just a little wiping. Pretty impressive.

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So while my bike was mostly disassembled, I thought I might as well replace the cables too. We happened to have scored a couple sets of Gore RideOn cables to test at Interbike. I took the old cork tape off the bars and cleaned the adhesive residue off, only to find a suspicious-looking line… was that a crack?

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Yes it was, and there was a matching one on the other side. I inquired with the fine folks at Easton and found out that the older yellow paint on my bars was not as flexible as the newer stuff, so it was possible that the cracks were not structural. However, I wasn’t totally sure of the exact age of the bars, as they’d come on the bike when it was a tester, and while I hadn’t crashed the “holy heck” out of them (in the words of the Easton rep, Sean Coffey), they had survived quite a few minor bangs. Witness the shifters:

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So new handlebars were also in order.

Then there were the brakes… this bike has Avid BB Road mechanical disc brakes, which as the name implies, contain actual ball bearings, which are user-serviceable. If something is user-serviceable, it’s probably a good idea to do so, ideally before three years of use and abuse have been heaped upon it, as was the case with my brakes. I had previously tried to overhaul them in the spring, but the parts were long since corroded and stuck together from all the wintertime salt on the roads. Since then I had been dealing with the fact that they were no longer adjustable, and with some unholy squealing noises, and with decreasing braking power. Time to remedy that.

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OK, now all of that was done, finally time to ride the ol’ Stumptown once again. I made it in to work, and realized that the seat height was not quite right, so I went to unscrew the pinch bolt to adjust it, when… PING!

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The threads in the seat collar snapped and came out with the bolt. Huh.

Justin helped me jerry-rig up a different bolt with a nut to get home.

Now I have a new/old bike with new cables, brakes, chain and chainring, and with everything else cleaned, tuned and generally spiffied up. Holy cow, what a difference in the ride! I am particularly amazed at the difference in the handlebars. Apparently Easton has been monkeying (no pun intended) with ways to manipulate the carbon layers in their handlebars to make them more compliant in the downward direction to absorb more vibration, but to remain stiff in the upward direction, such as when pulling hard in a sprint. Our very own Saxonburg Blvd. got a nasty coating of rough “chips” in the asphalt a couple years ago that rattles our teeth, but suddenly, with the new bars, the rattling is turned way down. And wow, it sure is nice to have brakes that work reliably again. I promise to give those ball bearings some love before 2012!

9 Responses to “It All Started With a Chainring”

  1. S. cerevisiae Says:

    You just described every time I touch any of my bikes. Fix more than one thing to get at the actual repair needed. It is always amazing how getting grime out of bearings will decrease rolling resistance, and how torquing everything squelches squeaks.

  2. robcycle Says:

    Great blurb. Its nice to see pictorials and stories of other people problem solving their bikes.

    Oh, and loved the Stumptown review. Its nice to see you’re still riding it.

    -Rob.

  3. mooseknuckler Says:

    As a professional wrench for the past 14 years, you just described my every day life to a tee. Bike comes in for a tune up, chain is worn, needs new tire, probably a good idea to overhaul bearing components, oops, now we’re talking $200 + to get the bike running like new but the customer only wants to spend $50. The public just doesn’t understand preventive maintenance and its benefits. After all, it’s just a bike, a toy, why would someone want to take care of it?

  4. Karen Brooks Says:

    Thanks guys!
    It’s definitely way easier, and more fun, to do this sort of thing to your own bike. No convincing needed (except maybe of your spouse!).

  5. fixyobike Says:

    Mooseknuckler, as a fellow wrench, you hit the nail on the head with a ten pound sledge hammer. There is nothing more frustrating, than when a customer drags a bike in that is within a millimeter of it’s life and proceeds to tell you that it “just needs a basic tune up.” Only to make it worse when you quote that $200 and they still just want to spend $50. But I digress, bike wrenches of the world, keep up the good work.

  6. GrantB Says:

    How tough were the BB7 brakes to overhaul? The instructions per Avid look simple enough, so I guess the real issue is keeping stuff together and in the right order? I have a set I’ve been running with exactly no maintenance since something like 2003 or so. I had promised them some love back in the fall, but now they have been pressed into duty again through the winter….

  7. Karen Brooks Says:

    Hey GrantB,
    It wasn’t too difficult to overhaul the outboard side that contains the bearings, once I soaked the calipers in enough PB Blaster to get it apart. The inboard side stayed frozen though. There was so much corrosion on the pistons (called “pressure feet”) that it was pretty much impossible to clean them back to good working order. (The city puts a lot of salt on the roads in winter!)
    For your older brakes, you’ll need a specific tool to take apart the bearing side, called simply the Mechanical Disc Brake Tool, which is available to any shop through Quality Bike Products (part # TL6934). It looks like a small cassette tool. Newer Avid BBs don’t need this, as the calipers are two pieces held together with two bolts. The older calipers are one piece, and the bolts just add strength… don’t bother removing them to try to disassemble the calipers, like I did at first.
    The directions on the Avid site are for the newer brakes, but most of the steps still apply, and if you are mechanically inclined it’s not too hard to figure out how to use the tool. Like you said it’s mostly a matter of keeping the parts together and in the right order.

  8. Karen Brooks Says:

    Just found instructions for the older brakes that need the tool (on page 33):

    http://www.sram.com/_media/techdocs/2007%20Avid%20Technical%20Manualweb%2095-5015-004-000RevA.pdf

    And according to this, the tool is called the Avid MDT-1 Lockring Tool. Hope that helps!

  9. Dirt Rag 1.25.09 | Momentum Bikes Says:

    [...] Karen BrooksSome weeks ago Karen set out to replace worn-out large chainring on her commuting bike. As often is the case with bicycle maintenance, one thing led to another and a simple job turned into a project. Read it…. [...]

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