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Rim caliper brakes slow us by pressing the pads into the rim.
That robs the wheel of energy and momentum.
The pads also take away a little bit of material, and over time that can lead to rim failure.
How do we know when it's time to replace the rim?
That's coming up on this week's Tech Tuesday.
hello Calvin Jones here, Park Tool Company, with Tech Tuesday.
Rim wear is especially an issue with aluminum rims
and if your pads have dirt and sand in them, you're essentially braking with two pieces of sandpaper.
But even on a clean pad, there's going to be some material loss.
Over time, that can weaken the side wall which must withstand the outward pressure of the tire
and if it can't, it will lead to this -
You can see the rim bent outward giving way to the pressure from the tire,
causing an instant blowout.
But again, how do you know when it's time to replace your rims? Get groovy!
Newer wheels have wear indicators made into the braking surface.
Look for a machined groove. These small divots are another style.
Once the wheel is worn where these cannot be seen, it's time to replace the rim.
In this wheel, our indicator line is completely gone - this rim needs to be replaced now.
This rim still has the indicator line, so keep on truckin'.
Older rims lack that indicator line, but if you can feel a dished surface
it's from the wear of the rim, and the rim should be replaced.
Don't mess around with weakened rim sidewalls, cuz they ain't groovy.