Tour Easy: Long-Deferred Drivetrain Maintenance

A few months back, the 13-tooth sprocket on my Tour Easy started skipping, which reminded me that I planned to replace all the drivetrain components. Time passed, the winter remained unseasonably warm and sunny, we kept riding, the skipping got much worse, and I just shifted across that sprocket.

Finally, the rains returned, I heaved the bike up on the workstand, and started replacing things. Judging from the accumulated crud and severe wear, it’s been on there for quite a while:

Sprocket with broken teeth - as found

Sprocket with broken teeth – as found

Here’s the offending 13-tooth sprocket, all shined up;

Sprocket with broken teeth - detail

Sprocket with broken teeth – detail

I don’t recall a catastrophic failure that stripped all those teeth off in one shot. A closer look showed cracks in the few remaining teeth:

Sprocket with broken teeth - cracked teeth

Sprocket with broken teeth – cracked teeth

Which explains why the skipping gradually got worse: the poor sprocket shed teeth as I rode blithely along.

Huh.

That’s what happens with a severely worn sprocket: the chain applies tension to just the topmost tooth, rather than distributing it on the teeth around a third (or more) of the sprocket, and, one by one, that force breaks the teeth. The top picture shows at least one other sprocket with a missing tooth; all display the shark-fin profile of heavy wear.

As you can tell from the other bike pix & repairs around here, I’d rather ride than mess around with cleaning and suchlike. We’re on our second set of drivetrain components in 15 years, so I’d say treating all that stuff as consumable seems a fair tradeoff…

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  1. #1 by Daniel B Martin on 2016-03-16 - 08:40

    Ride it until it breaks!

    What is your preferred source of replacement parts? Is a super-long chain available or do you splice garden-variety chains?

    • #2 by Ed on 2016-03-16 - 09:18

      Quite a few years back, I stocked up on Nashbar “recumbent length” chains, but even those require another half of a standard length Nashbar chain; a Tour Easy uses something like 2-1/3 standard chains.

      The chains wear at half the rate they would on an upright bike, so I just let everything wear out together.

      I rebuilt the drivetrain on Mary’s bike last year and there’s a bundle of SRAM standard chains on the shelf for the next time …

  2. #3 by tantris on 2016-03-16 - 10:34

    Has that drivetrain hit the trash, or have you kept parts of it “just in case you might need it for something later” ?
    Just curious….

    • #4 by Ed on 2016-03-16 - 11:29

      In line with my current effort to, ahem, lighten the load, that junk hit the trash can with a resounding clang… followed by a brief period of dizziness. [sigh]

      • #5 by tantris on 2016-03-16 - 11:48

        Thanks! My wife is wrong, it is curable :)

        • #6 by Daniel B Martin on 2016-03-17 - 08:17

          Not curable. A temporary remission is the best we can hope for. So says one who knows!

      • #7 by Vedran on 2016-03-17 - 09:28

        Try recycling :) When I junk stuff into appropriate recycling containers I don’t feel like I’m giving something useful away… more like finding it a new warm and loving home… in case of metals fiery white hot home :)