Rim wear

[honesty]

I’ve got an DT Swiss RR465 rim on my rear wheel. It’s got wear indicators, small holes, on both sides. On my rim the holes are still visible on one side but one the other they’re only tiny pin pricks. Time to change the rim out or wait til the pin pricks go completely? And before you say measure with a calliper, I can’t I don’t have one!

[Brucey]

If you can manage ~£5 you can buy an Iwanson gauge from e-bay. Digital calipers are not much more money and have so many uses I would be lost without them.

If you are determined not to buy a tool for the job, another way you can tell if you are sailing close to the wind is if the rim gets appreciably wider once the tyre is fully inflated. You can cut a cardboard or plastic template that is a good fit over the rim (when the tyre is deflated) and use that. Compare with a 'known good' rim of the same type.

cheers

[Paulatic]

Coming soon at an ALDI near you £7:99. https://www.aldi.co.uk/workzone-digital ... 0189831100
Once you’ve got one you’ll wonder how you ever lived without it.

[francovendee]

Coming soon at an ALDI near you £7:99. https://www.aldi.co.uk/workzone-digital ... 0189831100
Once you’ve got one you’ll wonder how you ever lived without it.

I bought a similar one from Lidl for my son. Coming from a lifetime in engineering I can't think how people manage without one

[John1054]

Coming soon at an ALDI near you £7:99. https://www.aldi.co.uk/workzone-digital ... 0189831100
Once you’ve got one you’ll wonder how you ever lived without it.

Nice one!

[iow]

I’ve got an DT Swiss RR465 rim on my rear wheel. It’s got wear indicators, small holes, on both sides. On my rim the holes are still visible on one side but one the other they’re only tiny pin pricks.

just out of interest, how many miles on the rim?

[honesty]

I’ve got an DT Swiss RR465 rim on my rear wheel. It’s got wear indicators, small holes, on both sides. On my rim the holes are still visible on one side but one the other they’re only tiny pin pricks.

just out of interest, how many miles on the rim?

6000 ish. I don’t split recorded miles between my bikes so that’s an estimate (guess!).

[Chat Noir]

Thanks, Paulatic, just ordered a digital caliper for £7.99 including free delivery - bit of a steal, really.

Can now replace the ancient and erratic digital one my brother gave me.

Cheers!

[NATURAL ANKLING]

Hi,

Coming soon at an ALDI near you £7:99. https://www.aldi.co.uk/workzone-digital ... 0189831100
Once you’ve got one you’ll wonder how you ever lived without it.

I bought a similar one from Lidl for my son. Coming from a lifetime in engineering I can't think how people manage without one

Micrometers etc.

[NUKe]

Digital Callipers as shown in Paulatics post so how do you measure Rim wear with one? Assuming your your brake blocks are not larger than the RIm your rims will not be evenly worn Rim wear is concave ? So how do you use the Digital calliper to measure the wear ? so unless you modify the calliper you will just measure the highest point ? just intrigued

[Paulatic]

Strip of metal - measure it- lay it in brake block wear groove and measure total width - take away width of known bit of metal You are left with thickness of rim.
At least that’s how I do it.

[andrew_s]

If you can manage ~£5 you can buy an Iwanson gauge from e-bay. Digital calipers are not much more money

For easy rim wear measurement, an Iwanson gauge is better.

Calipers don't reach underneath the overhang of the rim hook, or any less worn section at the edge of the rim.
You can add spacers, and measure spacer+rim+spacer, but it's a bit of a faff.
Alternatively, if you've already got a near redundant cheap caliper, you can cut away the jaws just below the tip to leave space for the rim hook.

[Brucey]

Digital Callipers as shown in Paulatics post so how do you measure Rim wear with one? Assuming your your brake blocks are not larger than the RIm your rims will not be evenly worn Rim wear is concave ? So how do you use the Digital calliper to measure the wear ? so unless you modify the calliper you will just measure the highest point ? just intrigued

get a short length of 14G (2mm) spoke, and shape it so that it can be laid below the rim lip inside the rim. Zero the calipers on the spoke diameter. Use the calipers across the spoke (in position) and the rim. The reading is the rim wall thickness. Take several readings at different points around the rim.

If the rim is slightly concave, the caliper jaws will have to be slightly angled to get a reading, but this won't produce a large error, unless the rim is very concave in which case you probably don't really need to measure it. A variant of this technique (as used by CJ) is to make a 'clip' from the spoke that leaves a piece of spoke inside and outside of the rim. Zero on the clip when it is closed, or subtract 4mm from the reading.

Colin has, I think, ground a couple of grooves into his Vernier caliper jaws so that you can measure a rim directly. At £7.99 it is worth a go.

Note that this method measures the rim thickness where it is arguably most important; a failure just below the bead lip will cause the tyre to blow out and the brakes to perhaps jam.

However it is also possible for rims to wear lower down, so that the wear breaks through into the box section. Some rims are designed so that the rims breaks through at this point before it is in danger of failing higher up. This breakthrough does nothing for braking but it is at least unlikely to cause a catastrophic accident. Annoyingly you don't know how much wear is left in the rim with this kind of rim; this means that you are best advised to replace the rims before a tour if they are more than half-worn; they could break through with no warning mid-tour otherwise.

cheers

[spider2106]

lots of useful tips, you will end up with a dimension. BUT what is the min. amount of material for safety?

[Brucey]

it varies a bit with the tyres that are fitted, the pressure and the strength of the aluminium alloy that the rim is made out of. But having said that most rims don't actually fail until they are under 0.7mm thickness. They start out between ~2mm and ~1.0mm thickness. Most rims fall into a range between 1.3 and 1.6mm these days when they are new.

BTW I am not a very big fan of rims with machined sidewalls, because (IME) the machining is never perfectly consistent; it is very common to find that the wall thickness is not perfectly uniform in a new rim and this can lead to premature failure in some cases. The excuse is that a rim with machined sidewalls makes for smoother braking when the rim is new. It does, but a new rim without machined sidewalls needs to be pretty badly made before it causes noticeable problems that last more than a short while.

If you measure 0.8 or 0.9mm, it is probably time to plan for a replacement in most cases. Probably the rim will start to look more concave than it really is (through wear alone) at about this time, because it usually flares slightly when the tyre is under pressure.

I measured some properly failed rims and they mostly measured about 0.5mm thickness where they had actually split. I don't recommend that you leave it this long!

If the rim is designed to wear through lower down, they can get a lot thinner before there is a split. Sometimes the rim develops a wrinkle just before it breaks though in this case, but IME it doesn't reliably give you any warning.

Just for fun I built a rim that had worn and split lower down into a wheel which I then gave merry hell (with a hub brake inside it) and it didn't cause any problems, despite flaring alarmingly. So such a rim is probably safe to ride on for a while, albeit you shouldn't use the brakes (rim brakes) on the rim any more for several reasons.

cheers