Replacing 26" Mavic MTB rims (non-disk) - what & where??

[gogo@]

Help! Asseblief. Have just discovered cracks around 4 spokes (2 "top", 2 "bottom", drive side) in my 3-year old Mavic XM719 rear rim (expletive deleted).

Need to find a replacement.

CRC is my normal go-to (and where these wheels came from) but I'm not finding much there.

I don't think it will be Mavic. Can't afford to replace wheels every couple of years, especially when they haven't had to do the work they're supposed to be capable of...

So, what to get and where to buy?

Anyone in this country still able to supply v-brake rims?

This is for an all-purpose MTB but intended for touring/LSD riding -- strong not light is needed.

[gogo@]

Also, would these cracks (hairline splitting outward from the nipple) be a build issue, a rim issue, or something else?

The wheel has been trued once - a week ago.  It has run absolutely true until 6 weeks ago when I had the bb & cassette replaced for the first time.  The brakes were reset and came back "grabbing" the rim, so the search for the problem began.  And the problem seemed to get worse.  At that time I didn't notice any cracks, but there was a very slight wobble in the rim, so had it trued.  Could that have been the final straw?

[V12man]

I have a brand new Mavic/XT front v-brake wheel if you are interested - still has stickers/labels... Think it is a 312 from memory - will look if you are interested.

[David Marshall]

 

Also, would these cracks (hairline splitting outward from the nipple) be a build issue, a rim issue, or something else?

The wheel has been trued once - a week ago.  It has run absolutely true until 6 weeks ago when I had the bb & cassette replaced for the first time.  The brakes were reset and came back "grabbing" the rim, so the search for the problem began.  And the problem seemed to get worse.  At that time I didn't notice any cracks, but there was a very slight wobble in the rim, so had it trued.  Could that have been the final straw?

 

Those cracks are from metal fatigue.  This is unavoidable but wheel life can be extended by choosing then right rim, spokes and builder.  The XM719 rims are known for their propensity to crack - even with the eyelets.  I can get Alex DM 18 or DRC MT 17 for you in 26" rim brake.

[gogo@]

I have a brand new Mavic/XT front v-brake wheel if you are interested - still has stickers/labels... Think it is a 312 from memory - will look if you are interested.

Thanks!! Most appreciated if you keen to offload a wheel you're not using - I may just need to chase that offer.  Still have a Mavic soft spot even though I now wonder about rim cracks.  But let me see if I can find a rim/rear wheel?

[gogo@]

Those cracks are from metal fatigue.  This is unavoidable but wheel life can be extended by choosing then right rim, spokes and builder.  The XM719 rims are known for their propensity to crack - even with the eyelets.  I can get Alex DM 18 or DRC MT 17 for you in 26" rim brake.

I suspect it's the build then?  Not good.  Also see various bad reviews popping up warning that the XM719s are no longer the rim of choice, despite their earlier reputation.  These wheels have been looked after, never out of true, and haven't done a third of what the factory Alex rims did.  Tossed those because of rim wear.  There's some wear on these but the braking surface is still good.  Will be in contact re options. Thanks for the reply, was just looking up your contacts on the web!

[droo]

I"d have to see the wheel to confirm, but it sounds to me like metal fatigue caused by uneven spoke tension.

 

How many spokes are there, and are they double butted?

 

As for new rims, Mavic are available locally and they're definitely decent, but there are cheaper durable options out there. I'm not an expert on non-disc rims, but Dave Marshall will probably be along shortly with some advice.

[gogo@]

I"d have to see the wheel to confirm, but it sounds to me like metal fatigue caused by uneven spoke tension.

 

How many spokes are there, and are they double butted?

 

As for new rims, Mavic are available locally and they're definitely decent, but there are cheaper durable options out there. I'm not an expert on non-disc rims, but Dave Marshall will probably be along shortly with some advice.

Thanks for the reply, droo.

32 holes, straight, not double butted.

How fast could metal fatigue like this have occurred?  Seems it's only starting.

 

The cracks are on drive-side spreading each side from centre of eyelets, at 4 points almost opposite each other (i.e. 2 at wheel "top" and 2 at "bottom").  The longest is about 4/5mm.  It does look a little like the spokes might be starting to pull the at the rim?

 

I'm wondering two things:

1) could a wheel truing a week ago have caused this?  Because it's the only time the spokes have been touched in 3 years and the wheel was hardly if at all out of true.  There's an issue with the rim brakes "grabbing" which is why I had the wheel trued.  This started after replacing bb and cassette some weeks/a month ago (no problems at all before) so I assumed it had something to do with that process maybe.  Then I found these cracks when trying to sort the brakes out myself yesterday (haven't checked yet if the grabbing is still an issue).

Or would this have been developing over time?  How fast can aluminium crack like this?

Surely if there earlier, it would have been picked up when the wheel was trued, or earlier when the cassette was replaced?

 

Which leads me to:

2) since the cracks are small and not many, if there is a failure, am I right in thinking it will be in the order of a spoke failure? i.e., there might be some riding left in the rim?  I'm looking to replace, but it's not going to happen today, so wondering about riding for now, or not.

 

Help with the forensics is appreciated because these are brilliant wheels and I'm keen to replace with the same rim, but not if there's going to be a repeat.  I have ridden the bike with a light load (10-15kg) but I'm not exactly a buffalo on the bike either.  Most of my riding is dirt-roadie stuff although I was doing a bit of trail last year.  No proper drop-offs and few rock gardens to speak of.  Real granny stuff with the occasional hooligan turn (ah hem).  Tyres have been mostly 2.2's, and pressure between 1.9 and 2.2 as well.  The rims are rated for much higher.  So that's what I'm looking to replace for, with the emphasis on more touring and less trail.

[droo]

As Dave said, the Mavic rims are made of very hard alloy and are therefore quite brittle and prone to cracking. That said, if the wheels are properly and evenly tensioned you shouldn't have a problem. I'd also recommend double butted spokes since they allow the spoke to elastically deform in the middle rather than create stress risers at the J-bend and thread. A properly built and stress relieved wheelset should last you upwards of 10 years.

 

You don't say where you are, otherwise I could recommend someone in your area to speak to.