How do you judge if a rim has had its time?

[JohnMarin_77]

Hi there all,

I am just a shed tinkerer and I’d love some help from you chaps

I bought a lovey bike and with it came some wheels with m900 hubs. They have Matrix Singletrack Pro rims. The wheels seem true with no wobbly spokes

They are a bit grimy after a couple of decades in a quiet garage - but I don’t think they had a hard life

I see people say things like ‘plenty of braking surface’ and holding up a flat edge to them. I assume because a nice flat rim is best for an even braking surface?

So I wondered if I could get a bit of advice; what the quality of the rims I have, does the slight cupping the photos I attach cause me to worry, and how do I clean them up - or should I invest in new rims (happy to...)

If I did invest, what’s a good 26 rim that would match a lovely pair of xtr hubs?

Thanks all!

 

[greencat]

I'm sure I'll get shot down for this, and rightly so. But if they aren't going to be ridden hard - I wait until I start seeing cracks in the rim surface and then swap over pronto. That's obviously not advice you should take.

 

[rwm1962]

I found this recent thread interesting:
viewtopic.php?f=1&t=421777&hilit=rim+wear

I bought this cheap dental Boley Guage for checking mine.

 

[davez26]

Re:

I don't know of a cupping 'discard spec', but I had a set of those for the longest time, cupped, and they were much worse before the rim surface started cracking.
Do you plan on long days of shredding the GnaR on lift serviced terrain, or hitting paths from time to time?
If the latter, I'd run 'em, eyeball them once in a while, but I suspect you have a ways to go on those.

 

[mk one]

Most rims are flat when new so people try to show they havent got much wear.

Personally if my rims looked like yours i would still ride them, the only thing i would check now and again is the brake blocks, they can wear uneven when the rims are worn slightly.

 

[Tootyred]

I would stick with the rims you have. I would ride those....as others have said, just keep checking them a bit more religiously and expect the blocks to wear in an odd shape!

 

[hamster]

They don't look too bad to me. I use the depth probe part of a vernier to check, assuming rim walls are 1.0-1.3mm. Less than 0.5mm is definitely asking for trouble.

Another good way to measure is an Iwanson gauge - around £10 or so.