Cycling UK Forum

Possibly a silly question, sorry in advance.

I have been using disc brakes for a long time but recently brought an old (1992) Tange frame from a charity shop. It's fast becoming my favourite bike. It was center pull braked but whoever had it before me converted it to V. The wheels were shot as the rims had worn out. I put on a pair of wheels I had already that are disc ready with Rigida Sputnick rims.

So, silly, how long is a piece of string question.. How many miles should be expected to get from a rim? I get it depends on how much braking you do of course. How aggressive you brake blocks are. How heavy you are and how much your camping gear weighs. But is there any ballpark answer? I don't want to get rid of the frame in favour of a disc braked one but am running on a tight budget.

Thank you.

Depends on the rim sidewall thickness, the brake pad compound, whether you ride a lot on wet and/or dirty conditions (abrasive muck on rims) and whether or not you keep the pads clean and free from aluminium wear debris from the rim braking surfaces. If your brake make a grating noise it often means the brake pads are full of bits of aluminium. This wears the rims a lot faster (and gives less braking power).

My worst rim life is around 2,000 miles, from a Mavic rim that was only 1mm thick when new. You can buy an Iwanson gauge on eBay and use it to measure the braking surface thickness so you know when to throw the rims away. The guidance used to be 1mm thick but many rims are only around 1.3-1.5mm thick when new so you need to check periodically to avoid getting stranded somewhere with a sidewall blowout.

I use Koolstop Supra 2 brake pads in the salmon compound (it's sort-of salmon coloured) as I've found them the best for not wearing out rims prematurely.

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I can't give a distance either.

The point about measuring has been made above, including the use of those clever dental callipers although I do it by using a spacer and subtracting.

And some rims have visible wear indicators on the outside.

Jonathan

It is, as you say, a piece of string question.

I've had as little as 5500 miles, with aggressive brake blocks (Shimano), ridden all winter on frequently steep and muddy country lanes (this was with rims that hadn't been pre-worn out by machining the braking rurfaces).
Using more friendly brake blocks (Koolstop), with riding on flatter ground in mostly good weather, I've had over 30000.

The main conclusion I came to was that the most important thing to check on was the brake blocks. If you find embedded grit and silvery bits of aluminium embedded in them, don't pick out the bits and hope that will do - change the blocks for a different type. Good blocks pick up very little.

My experience was that the point of imminent failure was about 0.7 mm. Once you've calibrated your fingers, holding the rim across its width gives a quite apparent indication of the outwards bending of the flanges that precedes failure, and is much quicker than taking the tyre off to measure. You could also measure the new rime, then watch out for any /*increase*/ in measures width.

I wouldn't worry too much with Sputniks and it sounds as if you've found a very nice frame/bike.
Can I ask what it is?

Do keep your rims clean though - you can check the pads at the same time.
Maybe I'm perverse but I find rim cleaning strangely therapeutic.

A lot depends on where you ride. If like me you favour smooth unmade roads then rims get covered in grit when the road is wet. I've had a rim wear out in a year of riding. about 5000 miles.

The thickness at which the rims fail will also vary with tyre pressure and tyre width relative to the rim internal width.

Using 'wide' tyres relative to rim width will impose greater bending forces on the rim sidewall due to the angle between the tyre bead and sidewall (which is more acute, as the tyre sidewall tends to 'bulge' outwards from the rim, for a wider tyre), though offset to a degree by the lower inflation pressures typically associated with wider tyres.

It's not always possible to assess rim wear by feel based on the degree of concavity of the braking surface. If the brake pads are kept well aligned as they wear and the pads are kept clean then rim wear can be even the degree of wear not visible or detectable by feel. There's also no guarantee the wear will be equal on both sides of the rim, or even (for machined rims) that the sidewall thickness was equal to begin with!

Better to spend a fiver or so on an Iwanson gauge and measure the actual thickness. I tend to replace around 0.9-1.0mm thickness as I've had failures around 0.8mm.

I've lost count of how many rims I've worn through. If you only ever ride in dry conditions your rims will last a long time. As people have already mentioned the biggest factor by far is wet, dirty conditions such as country lanes. Dirt/mud mixed with water is a liquid abrasive that grinds the aluminium to a powder. I clean my rims every day when it's wet.

The Ryde sputnik used to come with a CSS (carbide) coating on the braking surface that reduced wear. It says here: https://www.ryde.nl/sputnik

"Also available with the famous Ryde CSS layer that will quadruples the life span at least."

You're meant to use special brake blocks with CSS rims because they wear out blocks at a fast rate.

I've just bought a Ryde Sputnik rim from sjscycles. Their site doesn't mention CSS so I'm assuming that my rim is not.

https://www.sjscycles.co.uk/rims-tape/3 ... im-silver/

bgnukem wrote:It's not always possible to assess rim wear by feel based on the degree of concavity of the braking surface. If the brake pads are kept well aligned as they wear and the pads are kept clean then rim wear can be even the degree of wear not visible or detectable by feel. There's also no guarantee the wear will be equal on both sides of the rim, or even (for machined rims) that the sidewall thickness was equal to begin with!

The really obviously detectable concavity isn't due to wear, but to bending.
Like this:

As I said before, it's easy to detect when the tyre is on. The downside is that it's a "change immediately" indication, rather than a hint to book a repair at the bike shop.

Eventually yes, when the rim starts to fail, but I've found a lot of worn rims appear to have concave braking surfaces, though it's probably just a case of there being a worn band where the brake pads have made contact vs. no wear outside that area.

When the rim starts to mechanically fail I've found it usually goes in one area first giving the telltale pulsing brake, so at least you might get the chance to ride home (and not use that brake). The pic upthread suggests it's not always as benign though!

As said, Sputniks have a wear indicator. Basically it looks like a groove cut into the braking surface.Once you see it you know you are nearing the end. This doesn't mean that rim will fail immediately as it is double walled. Find a picture of the cross section and you will understand (I've posted one on this forum, but can't remember where I got it from).

I replaced the rear Sputnik on my bike after about 40,000 kms, the front after 60,000 plus. Mainly long haul touring - BUT I rarely ride in the rain. A wet muddy day on a long descent can see a pair of brake blokes disappear - obviously not as bad for the rim, but how much you wear blocks is reflected in how much you wear rims.

Basically, if you can't see the wear indicator, don't worry and ride happy.


Edit - found it and it's better explained:

viewtopic.php?t=109035#:~:text=The%20safety%20line%20will%20'appear,are%20not%20worn%20just%20yet.