Rim wear?

wishitwasallflat

Lifted from my other thread (Crash Damage) but this question emerged as a distinct new topic so it seemed appropriate to re-post mods.

These are Mavic Open Pro rims with 1416 miles on them (many of those miles dirty country road winter miles though) always used with Koolstop Salmons - several questions for you folks if you don't mind -

1) Is this degree of concavity/wear any cause for concern?

2) Do Open Pros have any wear indicator? From searching on other sites (some US) it seems that some Open Pro rims have a hole in the rim which appears opposite the valve hole somewhere (there is an arrow on a sticker) when they are worn enough to be replaced. Apparently this hole which appears is drilled part of the way through from the inside and so it appears on the outside if the rim wears down far enough.

HELP - is this cause for concern or are my painkillers making me crazy paranoid about relatively new wheels - HELP ..

paul_onabike

Open pro rims last a lot longer than the mileage than you've done. The amount of wear visible in your pictures looks about normal for the use you have had. I generally run them until there is a definate bellowing out caused by the tyre inflation which can be felt with your fingers. The last Open pro I changed had at least 8000 all weather miles on it.
As for brake blocks I normally use something like shimano ultegra blocks, though I have used the cheaper bbb blocks but they wear out quickly - better the blocks than the rims. Try to keep the faces of the blocks clear of any metal debris from the rims, as this wears the brake surface quickly. If the blocks pick up a lot of metal debris then I would try a softer compound block. I once used a set of clarks green blocks and you could physically see the ally rim being worn away as there were bits of metal everywhere.
I dont know of a rim wear indicator on the open pro rims, though I couln't be certain that there isn't one

wishitwasallflat

Thanks Paul - I coulnd't believe a decent rim like Open Pro could be worn at 1400 miles.

Re definate bellowing out caused by the tyre inflation which can be felt with your fingers do you mean you can feel the rim bulge as you inflate it? That sounds really scary are you sure it's safe to run them till then or maybe I have misunderstood what you mean?

ugo.santalucia

Looks much better on this photo...

crankycrank

Keep your Koolstop Salmon pads. They are about the most gentle pads on alu rims available.

wishitwasallflat

Thanks all - anyone know how best to check rims like these and when they are too worn? I've seen posts about using vernier calliper or micrometers and that (I think) 0.5mm wear was the limit. Can't see anything on mavic site though.

cycleclinic

The Open pro has a thin braking surface. Not the best choice if you ride in wet weather while commuting in traffic and always on the brakes or if you ride on a lot of decent in wet weather and brake alot. They can wear out quickly. I think the rims have more life in them rt runnign them until you feel the rim distort under pressure is a bit scary. Mavic say and so do I change the rim when the braking surface is 0.9mm thick. Measure with two spoke and a caliper. Te CTC form has some info on this and they recomend a similar minimum wall thickness on any rim. The Open pro is a decent enough rim but those double eyelts to weight a bit so weight is saved elsewhere. The DT Swiss RR465 has a thicker braking surface as does the Velocity A23, H+ son Archetype Rigida Chrina.

ugo.santalucia

thecycleclinic wrote:

The DT Swiss RR465 has a thicker braking surface as does the Velocity A23, H+ son Archetype Rigida Chrina.

That's so NOT true...

cycleclinic

Well that what my measurements showed, there is no published data on this. I measure again tomorrow and post the results.

cycleclinic

braking surface thickness measured this morning.

Mavic OP 1.2mm
DT Swiss RR465 and 415 1.3mm
Veloity A23 1.2mm I was wrong on that one.
H+ son Archetype 1.4mm
Rigida chrina 1.4mm I thought this was thicker, I was wrong on that too.

So the Mavic OP does appear to have a thinner braking surface than other rims.

ugo.santalucia

thecycleclinic wrote:

braking surface thickness measured this morning.

Mavic OP 1.2mm
DT Swiss RR465 and 415 1.3mm
Veloity A23 1.2mm I was wrong on that one.
H+ son Archetype 1.4mm
Rigida chrina 1.4mm I thought this was thicker, I was wrong on that too.

So the Mavic OP does appear to have a thinner braking surface than other rims.

As a physicist you should know that your tenth of a mm measurements difference have to be taken with the due skepticism, especailly given the method is not exactly a validated one, but a bit of a botch up.
Thing is they are all the same, give or take and the real difference is the margin of safety... Dt swiss drill very shallow holes, which means if you stick to their rule, you have to replace a rim fairly soon. The holes disappear before the rim is actually concave...Mavic doesn't drill holes, so normally people keep them for longer in my experience... occasionalyl a bit too long, like in this case

http://paolocoppo.drupalgardens.com/con ... t-too-much

rolf_f

Surely the only sensible measurement is a caliper across the middle of the braking surface for a minimum worn thickness or a caliper across the rim edges to identify bowing out.

The rim itself is inevitably going to become concave because the brake pad will only wear the part of the braking surface it comes into contact with - and that's probably not the edges unless you spend a lot of time aligning your pads........

chrisw12

I'm quite proud that I blew an open pro descending Alpe D'huez :oops: . They're great rims but is this one of the great un-answered problems in cycling, 'when do you replace a rim'? If there's a tool to measure chain length and a tool to undo kmc missing links, surely there's a tool to be invented that'll tell you when to replace your rims?

wishitwasallflat

Thanks all very very helpful - looking at buying a set of calipers or micrometers. It seems most have very very variable reviews - so can anyone reccomend a cheap (under £20) one that would be accurate enough to measure rim thickness for wear (given that +/- 0.1mm seems the minimum level of accuracy needed)?

Maybe if one used the same caliper/micrometer always and measured a rim when brand new and then set say a 0.3mm decrease from new thickness as the limit that would be wiser? I am wondering here if reliability may be easier come by than validity in cheaper devices?

andrew_s

Verniers and such have problems reaching the inside of the rim sidewall underneath the bead hook.
Something like an Iwanson dental gauge is best.

Rims seem to fail at about 0.7mm wall thickness (with road tyre pressures), so aim to replace if you measure at under 1mm.
If a rim's on the verge of failing, the outer part of the sidewall starts to bend outwards so that the dishing of the braking surface is much more pronounced that it would be just due to wear alone. It's quite easy to feel with the fingers once you some experience, but it does mean replace now, rather than next week.

I think that the rim wear indicator on Mavis rims is a small hole that appears in the braking surface somewhere in the vicinity of the label.

wishitwasallflat

andrew_s wrote:

Verniers and such have problems reaching the inside of the rim sidewall underneath the bead hook.
Something like an Iwanson dental gauge is best.

Rims seem to fail at about 0.7mm wall thickness (with road tyre pressures), so aim to replace if you measure at under 1mm.
If a rim's on the verge of failing, the outer part of the sidewall starts to bend outwards so that the dishing of the braking surface is much more pronounced that it would be just due to wear alone. It's quite easy to feel with the fingers once you some experience, but it does mean replace now, rather than next week.

I think that the rim wear indicator on Mavis rims is a small hole that appears in the braking surface somewhere in the vicinity of the label.

Thanks Andrew-s

cycleclinic

I used two 1.8mm spokes to help measure under the hook I them measured as I desribed with the vernier as I desribed in an earlier post. This get around that problem, I thought of that! Mavic OP do not have a wear indicator.

andy_wrx

Does no-one read the Workshop articles on BR ? :x

This one shows how to measure
http://www.bikeradar.com/gear/article/w ... nts-20934/
and suggests replacing when < 1mm

For cheap calliper, keep an eye on Aldi & Lidl - periodically a very serviceable digital one for about £7 when they have a 'tools' special week

chrisw12

But some Shimano wheels are marketed as having only 0.7mm rim thickness to start with :?: Which then leads to the question, how can you genralise that all rims from all manufacturers will be unsafe lower than 1mm?

ugo.santalucia

chrisw12 wrote:

But some Shimano wheels are marketed as having only 0.7mm rim thickness to start with :?: Which then leads to the question, how can you genralise that all rims from all manufacturers will be unsafe lower than 1mm?

They probably refer to the V part of the rim... the brake track must be thicker

majormantra

andy_wrx wrote:

For cheap calliper, keep an eye on Aldi & Lidl - periodically a very serviceable digital one for about £7 when they have a 'tools' special week

Same price or less on ebay, any time.

itboffin

If you take your tyres off every few weeks and really clean the wheels, run your wheel rims between your forefinger and thumb both sides and if there's a noticeable curve you'll feel it.

I found this more successful method than a straight visual inspection.

rolf_f

itboffin wrote:

If you take your tyres off every few weeks and really clean the wheels, run your wheel rims between your forefinger and thumb both sides and if there's a noticeable curve you'll feel it.

I found this more successful method than a straight visual inspection.

You'll get that though anyway. The brake blocks can't help but to wear the rim into a concave shape and it doesn't take long for that to happen if you ride in the wet - the important thing is whether or not the concavity is caused by wear or by the rim bowing out. Campagnolo just tell you what the inner width of the rim should be (15.5mm irrc) - if it doesn't measure that, then the wheels are toast!