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Ambrosio Excellight - cracks around spoke eyelets

WappygixerWappygixer Posts: 1,396
edited June 2010 in Workshop
Just been cleaning my rear wheel and I noticed a few cracks in my rim.
The cracks are all around the spoke eyelets on the drive side only and some are pretty big too.
The rims have only done 1500-2000 miles since they were built last year.
I'm a bit gutted to be honest and not sure if I want to replace it with another Excellight.
I may have to as I don't want to waste my CX ray spokes as they may not fit another rim build.
Anyone had similar issues?
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Posts

  • maddog 2maddog 2 Posts: 8,114
    ouch :(

    over-tensioned?
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
  • andypandyp Posts: 8,354
    Multiple cracks would suggest over tensioning rather than a rim fault. Who built the wheels?
  • WappygixerWappygixer Posts: 1,396
    They were built by a good friend of mine who is a very experienced wheel builder.
    I have had creeking on the rear wheek since it was first built and I've put it down to the spokes rubbing on the cross overs, a little lube and it went away.
    I don't think it was over tensioned but Ambrosio don't list and maximum tension for their rims.DT do a similar rim the 415 and it will take 1100Nm
  • balthazarbalthazar Posts: 1,566
    I don't believe the rims were over-tensioned. I've never built a wheel with these rims, but they are dimensionally and structurally similar to the Mavic rims I'm used to. Those can be built according to Jobst Brandt's archetypal method, wherein the rim's stability is the limiting factor for spoke tension, not the spoke bed which is well supported by sockets and eyelets. To my mind, a rim which can fail in this way is a flawed design.

    However, the failure is identical to that which claimed many Mavic MA-40 rims years ago, and in that case the cause was the hard anodising, a brittle surface treatment which was crazed into stress-raisers when the rims were rolled into hoops from straight stock. Those initiated fatigue cracks through the rim itself, something the identical (but not anodised) MA-2 never suffered from. That would be my first suspicion.

    In any case, this is a rim failure, not a building error, and you might seek redress if you can be bothered. I'd look out for plain (or at least, not hard-anodised) versions of the same rim, though, to keep your spokes, and perhaps let Ambrosio see your fine pictures of their failed product.
  • WappygixerWappygixer Posts: 1,396
    Just taken it into work for my wheel builder to look at.
    On closer inspection the drive side eyeleys have started to pull through the inner rim.Even some of the non drive side have developed small cracks.
    The inner eyelets have moved also and gaps are visible between them and the rim.
    Its always been a problomatic wheel so I wonder if its been the rim all along?
    Anyway I'm caling RSI the importers tomorrow and see what they say.
    If I have to buy a new rim I'm a bit reluctant to buy the same again
  • balthazarbalthazar Posts: 1,566
    Wappygixer wrote:
    Just taken it into work for my wheel builder to look at.
    On closer inspection the drive side eyeleys have started to pull through the inner rim.Even some of the non drive side have developed small cracks.
    The inner eyelets have moved also and gaps are visible between them and the rim.
    Its always been a problomatic wheel so I wonder if its been the rim all along?
    Anyway I'm caling RSI the importers tomorrow and see what they say.
    If I have to buy a new rim I'm a bit reluctant to buy the same again
    They may be similar enough to Mavic Open Pro that you could use them without replacing the spokes: I'm sure somebody on here will know, or you could check Damon Rinard's Spocalc. Open Pro aren't perfect but they're as good as any rims I'm aware of, and common enough that they're proven in the market.
  • Lynx_516Lynx_516 Posts: 14
    To my engineering eye it is impossible to determine the cause of the failure without a more detailed view of the cracks.

    However, if you trust your wheel builder I would tend towards a rim failure ( I hope it isn't because I have a pair of these!). But my first reaction and my reaction from what you describe I would think it would be to high tension for that specific rim, which may have been compromised by a manufacturing flaw.
  • How much do you weigh, and how many spokes are on that wheel?

    That rim is not like the DT Swiss RR415 rim. It is more like the RR465 rim since it has double eyelets. But the Excellight weighs 430 grams, and is one of the lighter double eyelet rims available. Since you want to save the spokes, the ERD I measured for that rim is 603mm (if I remember correctly) which is about the same as I measured for a Mavic Open Pro rim.

    It is normal for rims to develop cracks on the drive side eyelets over time, but yours seem premature. Those rims should be able to take 100-110KGf of tension on the drive side without a problem (DT specs 120KGf max for the RR465). I have a set of those (32 spokes) with a 200lb rider with probably 3-4k miles so far without any cracks or other problems.

    http://www.valleycyclist.com
  • I had exactly the same problem a few years ago on an Ambrosio Evolution rear rim--I had it rebuilt with an open pro rim, and its still going strong. The front Evolution rim is still oK.
    The wheel builder at the time said he had seen the problem on other Ambrosio rims , and the wheels were a couple of years old at the time, so I put it down to experience and haven't used Ambrosio rims again. I have never seen that problem on a Mavic rim,.
    I don't suppose this helps you very much, but at least you're not alone!!

    Rich
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