Tuesday, April 5, 2011

Poke Yoke, Bikes and Safety

Poke Yoke, bikes and safety don't seem a natural combination.  The rear wheel on my bike I knew was coming to the end of its life, when that would be I didn't know.  And the integrity of a real is an important issue, a real safety issue.  With lots of stop start cycling in Calgary with all the stops signs and the age of the wheel, the wheel has undergone a lot of braking action. Most brakes on bikes use the rim as the braking surface. This surface wears and at some point the rim either fails or the braking surface detaches from the rim. This is what happened to me, the braking surface started to come loose and each time the wheel rotated it rubbed up against the brakes.  Letting me know something serious was up.
Next step was to get the wheel fixed, so off to Lifesport in Kensington.  Wheel building is a skilled job and one best left to the experts.  First step was to choose a new rim. For the type of use this wheel gets (all year cycling and some cyclocross racing) there were two choices the Mavic Open Sport or Open Pro. I'm a snob, I was replacing a Open Pro rim so I went with the Pro again, but I did think about it. Ok only for a couple of miliseconds.

The Sport comes with this lovely black line along the rim:, its actually a wear groove :
Actually its a wear groove about 1.5mm deep. When you can no longer see or more likely feel with your fingers its time to replace the rim and stay safe.
The Pro is lighter and doesn't have the structural shape to carry a wear line
Of course I paid the extra $30 and went with the lighter rim, but no Poke Yoke wear groove and a little less safety knowledge down the road.

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