XTR Rims Warranty???

[Odion]

Does anyone know what the warranty is on Shimano XTR rims. I found a hairline crack at the valve, so it's not holding air. The rims are just over a year old, so hoping the warranty is not 12 months. Anyone know???

[Johan Bornman]

Does anyone know what the warranty is on Shimano XTR rims. I found a hairline crack at the valve' date=' so it's not holding air. The rims are just over a year old, so hoping the warranty is not 12 months. Anyone know???[/quote']

 

I can't help you, I suggest you phone Coolheat. However, I'll be very interested to have a look at that crack. It'll be interesting to see where the crack started and how far it propagated. So much for the super-tough scandium alloy.

 

Do you have a camera with a good macro function for some photos please?

 

[Odion]

 

[Johan Bornman]

Thanks. It is quite interesting that it should crack from the valve hole outwards. There's very little stress there and certainly none of the cyclical stress found at the spoke holes.

 

It appears as if there is quite a nasty burr there on the inside of the hole, I wonder if the crack started there? Where's Greatwhite, Bruce, Straatvark, Lefty, Edman and Christie?

 

[Guest Big H]

Johan, what do you think is the mark on the front of the picture, could that have been a mark left when the rim was bumped or banged against something????? Could a bump there cause a crack?????? Funny place as you say it is unstressed.

Bit off topic, I read somewhere today that the little hole some people drill in the BB shell to drain water can cause the BB shell to crack???? Is this possible???

[greatwhite]

Johan' date=' what do you think is the mark on the front of the picture, could that have been a mark left when the rim was bumped or banged against something????? Could a bump there cause a crack?????? Funny place as you say it is unstressed.[/quote']

 

I'm with you on this - my guess, the rim took a knock in the valve hole area - the right hand crack came 1st and the left hand one is more recent.

 

The valve hole area is more stressed than many think and sometime subject too abuse too (valves twisted of knocked etc)

 

Eldron might give some info, this sort of thing is more in his line.  (Does anyone have any info on scandium fatigue characteristics?)

 

 

Bit off topic' date=' I read somewhere today that the little hole some people drill in the BB shell to drain water can cause the BB shell to crack???? Is this possible???[/quote']

 

Possible (but improbable) - especially is the hole wasn't deburred and clean nicely

[Johan Bornman]

I can't figure out what that mark is. Perhaps Odion can give us some insight.  I'm still not happy that this is a stress crack from abuse at the valve. If the valve had received a powerful knock in the up-down plane of this photo (The only way a knock would have initiated the left-right crack), I would have expected some evidence of deformation around the valve hole.

 

I don't know if that rim is anodised or painted. If painted, the spot can be explained. If anodised, I'm clueless.

 

Looking at the surface of that rim, I think it has been shot-peened in order to create some surface tension and make it stronger. This works but not if holes are drilled through the peened area, it would give plenty of points for the crack to start.

 

I don't think there is more than two molecules of Scandium in that alloy. The stuff is so expensive and so precious that I think the legal minimimum of two molecules is in there just to justify the Scandium Technology sticker and R7000-00 (?) tag.

 

 

 

[Johan Bornman]

Bit off topic' date=' I read somewhere today that the little hole some people drill in the BB shell to drain water can cause the BB shell to crack???? Is this possible???

[/quote']

 

I don't think so. Those holes have been drilled in bicycles since the day BBs were invented and so evidence of that in the last 100 years. Most bicycles up to recently used to have a hole there in anyway for the bolt that holds the cable guide.

 

The hole is in cyclical compression and thus in little danger of cracking.

 

I drill all my bicycles and encourage all my students to drill holes there. It doesn't take much convincing if we take the BB off and a cup of water pours out.

 

 

[Guest Big H]

Bit off topic' date=' I read somewhere today that the little hole some people drill in the BB shell to drain water can cause the BB shell to crack???? Is this possible???

[/quote']

 

I don't think so. Those holes have been drilled in bicycles since the day BBs were invented and so evidence of that in the last 100 years. Most bicycles up to recently used to have a hole there in anyway for the bolt that holds the cable guide.

 

The hole is in cyclical compression and thus in little danger of cracking.

 

I drill all my bicycles and encourage all my students to drill holes there. It doesn't take much convincing if we take the BB off and a cup of water pours out.

 

 

 

Thanx.... el rapido is geboor ek sal nou Cavallo do Ferro en die Raleigh ook boor.

[Christie]

My first impressions are that an impact below the valve hole would cause the rim to deform inwards between the spokes. From gut feel only, I would guess that maximum tensile stress due to this around the hole will be located 90 deg around from the crack locations.

 

Speculating now, I think it could crack like that from overpressure. This could still have been caued by impact - if the tire was inflated to  max / high pressure, and the wheel takes a big knock on something sharp like a kerb/rock, the resulting pressure peak could make it crack like that. This would probably not happen if the tyre pressure was low. 

[chatterbox]

Odion , send the wheel direct to shimano if you have no joy from your lbs . They will ultimately have to make the warranty call. Speak to Jade or even pm steve on the hub  

[Odion]

Hi all,

 

 

 

You are right, the spot below the valve hole seems to be an impact

point. for the life of me, I can't recall when and how this happened.

Looking at that impact point I would have expected, the tyre to burst,

which hasn't occured. The other possibility I thought of is that the

valve took a knock and somehow impacted internally, however the outer

rim at the valve hole has no wear or abrasions, so that would rule that

out (no counterpoint to the impact).

 

I run these tyres at 3 bar, so I can't think the pressure is to high.

 

I agree with Johan, that regardless I wouldn't expect to see this

happen even if a direct knock had occured - especially for a R7000

scandium rim.

[Johan Bornman]

My first impressions are that an impact below the valve hole would cause the rim to deform inwards between the spokes. From gut feel only' date=' I would guess that maximum tensile stress due to this around the hole will be located 90 deg around from the crack locations.

 [/quote']

 

Do you mean an impact from the tyre side or from the hub side?

 

If you mean an impact from the tyre side (i.e. road impact), then I can visualise your tensile stress location but not the direction of the crack.

 

QUOTE=Christie]

 

Speculating now, I think it could crack like that from overpressure. This could still have been caued by impact - if the tire was inflated to  max / high pressure, and the wheel takes a big knock on something sharp like a kerb/rock, the resulting pressure peak could make it crack like that. This would probably not happen if the tyre pressure was low. 

 

This is of course, all speculation and half the fun.

 

However, I can't see overpressure opening up the inner spoke bed. I see it going into compression and the inner spoke bed going in tension.

 

I'll take a photo of an XTR rim in profile and post that.

 

 

[intern]

I'd say a year's use out of a wheel is pretty good value, if I think of how I bliksem mine. Get a new rim and lace it on. That's what I have to do with my Roval E5s. The rear one is toast, man!

[Christie]

I'm saying for the rim bending inwards, I would guess the highest stress around the valve hole would be here:

 

[Johan Bornman]

 

 

OK, here's the promised photo. Looking at this, I now realise I've been geometrically dyslexic all the time. I've imagined the crack on the hub-side of the rim and committed the double sin of overlooking the verbal clue - "doesn't hold air".

 

To me it's like one of those funny pictures that you stare at forever and suddenly something comes into focus and voila! There's a camel or a dolphin right there. I now see the curve as inwards rathern than outwards.

 

Now that I know my arse from my face, I agree that over inflation could cause that crack but as Odion said, he didn't overinflate it and why would he? It's not a mistake one easily make with MTB wheels. Beside, the tyres usually climb off the rim long before any rim damage can be done.

 

The photo doesn't show the rim's edges so we can't see if there is an impact dent there but I still don't think a blow over the hole will cause that type of crack.

 

I think the clue lies with that ugly and careless burr.