Repairing Vuma Quad

Discuss light weight issues concerning road bikes & parts.
cllrhodgen
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by cllrhodgen

That's great. Really well done to you! You're right though... they shouldn't have given in so easily... guess it's why zipp and easton stopped making their cranks - too much hassle with warranties / failures!

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Waldo
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by Waldo

Or it could be that SRAM purchased us after we developed that crank, which was rather expensive to make in the US.

Subsequently, the new Red crank was in development with a similar target mass and a price ~50% lower than the Vuma Quad. Pretty obvious business decision to discontinue our crank, really.

monchito, impressive work. Can I ask why you didn't send the crank in for warranty?
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by Weenie


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monchito
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by monchito

Hello, Waldo.

I didn´t send the cranks for warranty because i thought that the warranty was over (more than 2 years), and because the shop i bought it, here in Barcelona, are probably the more slow acting way people in the world. :noidea: What in any shop could be 2 days, in this shop will be more than 2 months for sure.

But the principal reason was that i thought that i could fix it, and control all the process. (and just two days without the cranks in my bike :D )

cllrhodgen, mnmasotto and you all, thanks for your comments :thumbup: , i really appreciate them.

egebhardt
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Joined: Wed Mar 19, 2008 8:38 pm

by egebhardt

So did the repair work this time?
I have one with the drive side loose. I highly doubt that can be fixed.
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jvanv8
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by jvanv8

Monchito, what type of play are you feeling in the cranks?
Lateral - side to side, or vertical - pedaling one crank forward and the other backward?
I've got one set with mild vertical play. Feels like a bad freehub or failing bb bearings when pedaling, but it's indeed the VumaQuad but I've yet to isolate the issue or attempt a repair. Not sure if this is what you are feeling as well.
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latman
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by latman

Was it cold there just before the bond failures ? aluminum (the axle) shrinks A LOT more than carbon/epoxy (the crankarm) and it might be possible that thermal issues have contributed to the failure ?

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monchito
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by monchito

jvanv8 wrote:Monchito, what type of play are you feeling in the cranks?
Lateral - side to side, or vertical - pedaling one crank forward and the other backward?
I've got one set with mild vertical play. Feels like a bad freehub or failing bb bearings when pedaling, but it's indeed the VumaQuad but I've yet to isolate the issue or attempt a repair. Not sure if this is what you are feeling as well.



Hi jvanv8.

Sorry for this six month of delay. Hard times...

I had vertical play only. In theory we could fix the lateral play just squeezing the nut.

Yes, i tried to repair the BB bearings few times ( when climbing i heard some annoying noise: clack, clack, clack) since i realized that the problem was with the vumaQuad. When finally i realized about the real problem i scared a bit, but finally was not a big deal. Just two tries to do it well, and still are working fine.

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monchito
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by monchito

egebhardt wrote:So did the repair work this time?
I have one with the drive side loose. I highly doubt that can be fixed.



Hi egebhardt.

Yes, the repair is still fine. And +7000 Kmts.

If the problem is in the drive side is more difficult to fix, but still possible.

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monchito
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by monchito

latman wrote:Was it cold there just before the bond failures ? aluminum (the axle) shrinks A LOT more than carbon/epoxy (the crankarm) and it might be possible that thermal issues have contributed to the failure ?


Sure that the termal issues have some influence in this problem, but i think that the main problem is a poor dessing, too trusting dessing (too trust in epoxy adhesive). If they had a toothing machining on the axis as I have done in mine they had not had any problems.

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mythical
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by mythical

egebhardt wrote:I have one with the drive side loose.
I had a similar problem and got rid of mine after basically getting nowhere with Zipp's customer service.
monchito wrote:Yes, the repair is still fine. And +7000 Kmts.

If the problem is in the drive side is more difficult to fix, but still possible.
That's impressive! How would you fix the drive side?
monchito wrote:i think that the main problem is a poor dessing
My thoughts exactly. It's the joints that are so hard to get right with carbon cranksets, especially with QC and larger production numbers. I'm very impressed with the current BB30 Exogram Red cranks though.
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monchito
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by monchito

monchito wrote:Yes, the repair is still fine. And +7000 Kmts.

If the problem is in the drive side is more difficult to fix, but still possible.
mythical wrote:That's impressive! How would you fix the drive side?


The first thing i would do is surgery :wink: , i mean, taking off the aluminium piece, make some new teeth in it (as i did in the axis) and put again in its place with epoxy/carbón fiber (taking care to put the piece parallel to the plane of the chainring).

The point is to make those teeth; otherwise you could do some little holes in the strategic places and fill up the space between aluminium and carbón with some epoxy paste (and a syringe), but I think that would be just a short-term solution. In fact, the first repair i did in my Vuma, i did just with puting some (very good) adhesive again, but that repair only lasted two weeks.

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