How worn can my rims get before replacing them?

alex_uk

I've noticed my brake pads have worn down the braking surface of my wheels over the years, so I'm wondering at what point the walls of the rim are considered too thin?

I've measured the gap using a vernier - so this is resting the foot of the vernier on the face of the rim, as if is was a big brake pad touching the upper and lower edges of the rim (i.e. spanning from "spokes side" to "tyre side"). Then the internal slide of the vernier is slid towards the rim until it makes contact, i.e. as if this slide is a really small brake pad actually touching the centre of the rim's surface.

Front wheel: 0.5mm (Bontrager Select 622x14 series 6000 spokes 28)
Rear whell: 0.35mm (Mavic Open Pro 622x15 S6000 spokes 32)

gavbarron

There is often a wear indicator on the run, either a dimple drilled into it or a groove around the rim, once this is gone, stop riding it. I bought a second hand bike a few years ago and on the way home the front wheel folded over on itself due to the wear and the tyre rolled off. Luckily I was bumbling along and stopped safely or it could have been worse, wouldn't fancy tyre rolling off on a hill, bend or in traffic

http://www.flickr.com/photos/7614264@N02/6665263269/in/photostream/

ugo.santalucia

In the absence of an indicator and assuming you have done your measurements correctly, you should have around 0.9 mm left at the front and abut 1.1 at the rear... roughly speaking... that means the front is borderline risky, while you do have a bit left in the rear.
Typically the rear wears out quicker, did they do the same mileage?

gavbarron

ugo.santalucia wrote:

Typically the rear wears out quicker, did they do the same mileage?

Surely that depends on the rider, my front always goes first as I brake more with the front than the rear

keef66

My fronts wear quicker; I hardly touch the back brake normally.

In the absence of a wear indicator I'd want to be measuring the actual thickness of the remaining rim. Google for techniques involving calipers and bits of old spoke etc to get over the lip of the rim

davem399

gavbarron wrote:

ugo.santalucia wrote:

Typically the rear wears out quicker, did they do the same mileage?

Surely that depends on the rider, my front always goes first as I brake more with the front than the rear

I find the rear wears quicker, as it is the one which picks up more grit in wet conditions. A couple of years ago, the rear split on my winter hack, yet there was plenty of life left in the front.

alex_uk

The rear is relatively new, the front is the original.