# Zipp Vuma Quad Crank --rings flexing



## skygodmatt (May 24, 2005)

My riding buddy just got a Zipp Vuma crank. 

I can't keep the Vuma Quad chainrings from hitting the cage of the front derailleur. It does that in many gears. That crank was very expensive and those rings flex like crazy. According to Zipp, this is not a problem. Wrong. The crank is on a Cervelo R3-Sl so theres not much frame movement. If you push on the ring laterally near the chain with your finger, they move like they're made of cardboard. He's 150lbs and I weigh 190lbs. We both grind away at the FD under normal power loads.
I know the crank spider is a 110mm with 53/39 rings. That's the problem I think.. Too much distance between the ring's teeth and spider assembly. I'd expect more from a $1200 crank. Anyone have similiar problems?
Thoughts?


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## Rubber Lizard (May 10, 2007)

Assuming everything is in proper adjustment/alignment and working order then you shouldn't have a problem. Since everything is proprietary on the Zipp crankset you can't swap rings out for some very nice Shimano dura-ace rings you are stuck with Zipp chainrings. 
If you really don't like it, sell it on ebay, it'll get gobbled up quick.


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## Juanmoretime (Nov 24, 2001)

No problem here and I use the VumaQuad with the same 53, 39 ring combination although I ride a Lynskey R320. I find them just as stiff as the Campagnolo Record Ultra cranks they replaced. I would suspect bottom bracket shell flex. 

It is a Cervelo are the cups coming un-bonded?


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## skygodmatt (May 24, 2005)

Cervelo R3's don't flex much in the BB. As far as the shell cups, it's a brand new frame but i'll check the cups.


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## gitoutdaway (Nov 28, 2007)

oh dear, i was thinking of geting the same setup this spring... please let us know how it goes.


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## dadoflam (Jan 19, 2008)

Interesting..I have a set of Vuma compacts which haven't given any problems of this type yet but after reading the above I conducted a bit of a subjective test on the chainrings by seeing what degree of lateral movement I could get by pushing the larger ring towards the downtube using my thumb on my bike and a selection of other products at LBS. There was a sufficient difference for me to have liitle doubt that they move more under this type of load than any of the others I tried (FSA, Record, Ultegra, UltegraSL etc) - Record chainrings were the next 'flexy' whilst the other were too close to call.

I gues to be pragmatic I haven't had an issue on the road yet (I'm 215lbs) as far as rubbing goes and as long as this is the case I am willing to accept some degree of movement as long as it does not affect performance as I have achieved a pretty good weight saving. Logically they are lighter because there is simply less alloy there. How much energy do you realistically lose with lateral flexing of the chainring given most of the load is parallel?

That said it is disappointing discovery given the product hype about the stiffness of the chainrings rings and if indeed this rather subjective assessment actually turns out to be correct.

Overall though I am very happy with them and the affectt hey have had on the feel of the bike.


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## Juanmoretime (Nov 24, 2001)

dadoflam said:


> Interesting..I have a set of Vuma compacts which haven't given any problems of this type yet but after reading the above I conducted a bit of a subjective test on the chainrings by seeing what degree of lateral movement I could get by pushing the larger ring towards the downtube using my thumb on my bike and a selection of other products at LBS. There was a sufficient difference for me to have liitle doubt that they move more under this type of load than any of the others I tried (FSA, Record, Ultegra, UltegraSL etc) - Record chainrings were the next 'flexy' whilst the other were too close to call.
> 
> I gues to be pragmatic I haven't had an issue on the road yet (I'm 215lbs) as far as rubbing goes and as long as this is the case I am willing to accept some degree of movement as long as it does not affect performance as I have achieved a pretty good weight saving. Logically they are lighter because there is simply less alloy there. How much energy do you realistically lose with lateral flexing of the chainring given most of the load is parallel?
> 
> ...


This is not a good indicator of ring stiffness since rings are not designed or meant to be pushed from the side. Its like people spinning a bearing by hand unloaded when the bearing is designed to be ridden at low RPM's with a load on them.


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## dadoflam (Jan 19, 2008)

Juanmoretime - I agree - as I noted the load on chainrings is mostly parallel to the rings and not at right angles which is largely what the lateral-finger-pushing-exercise illustrates - my noted consideration is that because the load on chainrings is not absolutely parallel has a small lateral aspect arising both from off-line chain direction and botton bracket flex that the Vumas may be giving a small degree of potential performance if they are a bit softer laterally than other rings - this is more a theoretical than practical proposition I am sure but skygodmatt's experience does raise the question.

I am very happy with the responsiveness opf my Vumas and have not had any chain rub issues noted by skygodmatt but on the other hand I am using compact configuration not standard.


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## Forrest Root (Dec 22, 2006)

dadoflam said:


> Juanmoretime - I agree - as I noted the load on chainrings is mostly parallel to the rings and not at right angles which is largely what the lateral-finger-pushing-exercise illustrates - my noted consideration is that because the load on chainrings is not absolutely parallel has a small lateral aspect arising both from off-line chain direction and botton bracket flex that the Vumas may be giving a small degree of potential performance if they are a bit softer laterally than other rings - this is more a theoretical than practical proposition I am sure but skygodmatt's experience does raise the question.
> 
> I am very happy with the responsiveness opf my Vumas and have not had any chain rub issues noted by skygodmatt but on the other hand I am using compact configuration not standard.


Well considering that BB or frame flex has no demonstrated deleterious effect on performance, chainring flex, I'll bet, has a magnitude or two less effect than those first to things. I'd worry more about aero drag caused by body hair.


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## redcorn (Jan 20, 2007)

*I have the same problem*

I just installed the Vuma Quads on a Cervelo SLC SL with the Sram Red FD. The large chainring looks like a noodle laterally when pedaling in the 53-11, 12, 13 and rubs against the front derailleur. If I compensate and let more slack out on the front derailleur set screw the chain pops off the crank arm side of the large chainring. Never had this issue with Dura Ace, Campy UT cranks only with the Vuma Quads. 

That being said I noticed when I spin the cranks the chain line moves laterally like a wheel that is not true. If I take the chainrings off and set them on top of a table the chainrings are flat but when bolted together on the crank arms they bend where the bolts hold them together laterally. Very dissapointed in how they hyped these chainrings to be the stiffest in the industry.

I can say the acceleration, stiffness and how solid it feels is as good if not better than Dura Ace by a small margin. 

SLC SL Bottom bracket area is one of the stiffest on the market right now so frame flex is not the issue.


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## bikeboy389 (May 4, 2004)

redcorn said:


> If I take the chainrings off and set them on top of a table the chainrings are flat but when bolted together on the crank arms they bend where the bolts hold them together laterally. Very dissapointed in how they hyped these chainrings to be the stiffest in the industry.


If this is happening, then it sounds like your problem isn't flex--it's that the crank spider isn't true. A much bigger problem, IMO.


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## redcorn (Jan 20, 2007)

bikeboy389 said:


> If this is happening, then it sounds like your problem isn't flex--it's that the crank spider isn't true. A much bigger problem, IMO.


My friend I ride with has the exact same set up as me and noticed his Vuma Quad does the same thing, the rings are not true laterally. The large chainring when spun deviates laterally which excerbates the rubbing of the front derailleur. He rides with Dura Ace though and I ride with Sram Red. We are conducting testing to see if its the front derailleurs causing the problems or the chainrings. Rubbing only occurs on the 53-11 combo under heavy loads.


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## bikeboy389 (May 4, 2004)

redcorn said:


> My friend I ride with has the exact same set up as me and noticed his Vuma Quad does the same thing, the rings are not true laterally. The large chainring when spun deviates laterally which excerbates the rubbing of the front derailleur. He rides with Dura Ace though and I ride with Sram Red. We are conducting testing to see if its the front derailleurs causing the problems or the chainrings. Rubbing only occurs on the 53-11 combo under heavy loads.


Is the poor alignment/bent-ness there when _*not*_ under heavy load? I got the impression (perhaps wrong) from your post above that merely mounting the chainrings on the spider caused them to deform. That's why I thought you might have a problem with the spider. Now it sounds like you're seeing the deformation under load, which would be a different issue entirely.


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## redcorn (Jan 20, 2007)

bikeboy389 said:


> Is the poor alignment/bent-ness there when _*not*_ under heavy load? I got the impression (perhaps wrong) from your post above that merely mounting the chainrings on the spider caused them to deform. That's why I thought you might have a problem with the spider. Now it sounds like you're seeing the deformation under load, which would be a different issue entirely.


You assumed right. Its there when no load is applied. I have seen it now with three different Vuma Quad cranksets. The chainrings are not true laterally when they are bolted onto the spider. The amount of deviance is .5-2 mm laterally. It does not sound significant until you put load on them and they deviate laterally another 2-3mm causing the big chainring to rub on the inner side of outter plate of the front derailleur. If you let the front derailleur set screw out to compensate for the rubbing you will cause the chain to pop off the big chain ring to the outside wrapping around the crank arm when going from 39 to the 53 chainring. Rubbing only occurs at 53-11 ratio under even light load. 

I emailed Zipp and waiting for an answer.


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## bikeboy389 (May 4, 2004)

redcorn said:


> You assumed right. Its there when no load is applied. I have seen it now with three different Vuma Quad cranksets. The chainrings are not true laterally when they are bolted onto the spider. The amount of deviance is .5-2 mm laterally. It does not sound significant until you put load on them and they deviate laterally another 2-3mm causing the big chainring to run on the inner side of outter plate of the front derailleur. If you let the front derailleur set screw out to compensate for the rubbing you will cause the chain to pop off the big chain ring to the outside wrapping around the crank arm when going from 39 to the 53 chainring. Rubbing only occurs at 53-11 ratio under even light load.
> 
> I emailed Zipp and waiting for an answer.


When you consider the small clearances most derailler setups ask for, .5 mm is significantly out of true, and 2 mm might as well be a meter. Hope Zipp can get you a decent answer on this.


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## redcorn (Jan 20, 2007)

bikeboy389 said:


> When you consider the small clearances most derailler setups ask for, .5 mm is significantly out of true, and 2 mm might as well be a meter. Hope Zipp can get you a decent answer on this.


I am trying to figure out if all front derailleurs from different manufactures do this with this crank or is it this crank specifically is causing the problems. The Red front derailleur has such tight tolerances that it could be adding to the problem. If anyone out there has campy, shimano or red with this crank and has the problem please post or if you dont have this crank and any of the above derailleurs please post. Best way to test this is put the chain on 53-11 and pedal with moderate force and see if your chain hits the front derailleur plates.


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## Kerry Irons (Feb 25, 2002)

*Here's the fix*



redcorn said:


> IThat being said I noticed when I spin the cranks the chain line moves laterally like a wheel that is not true.


This wobble is likely either a slightly off spider arm, or a slightly off chainring. Either/both is a very common thing (I won't say problem, because in most cases, it has no effect on performance).

Assuming that your BB is OK (i.e. not loose - it's extremely unlikely that it's bent), you have to straighten your spiders and/or chain rings. Hold a small screwdriver or other short, pointed object against the seat tube so that the tip just grazes the crank spiders as they pass. If the spiders are bent (most likely problem), you can even them out as follows:

Place the bike on its side with the crank supported on a block of wood at the axle. With another block of wood or a stout dowel placed at the end of the offending spider(s) give it a whack with a hammer. Check for change in alignment. If you got no change, hit it harder next time. Repeat until all the spiders are even. You may need to bend them away from the frame (brace the right crank on the block of wood) or toward the frame (brace the left crank).

Once the spiders are even, check the chain rings with the same technique except put the point of your screwdriver at the teeth of the rings (most likely the big ring only if the spiders are even). Straighten the chain ring by placing a large adjustable wrench over the ring with the jaws adjusted for a slip fit over the ring. Bend gently, and check alignment. Repeat until you've got it right.

Even with the chain rings dead straight, you still will get some deflection due to pedaling forces, but that should greatly improve your situation.


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## redcorn (Jan 20, 2007)

*Zipp will warranty the cranks*

Contacted Zipp and they were great with customer service stating that everything I have said above is not normal and to send the cranks back. Thats a relief. I will keep you guys updated.


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## Forrest Root (Dec 22, 2006)

Kerry Irons said:


> This wobble is likely either a slightly off spider arm, or a slightly off chainring. Either/both is a very common thing (I won't say problem, because in most cases, it has no effect on performance).
> 
> Assuming that your BB is OK (i.e. not loose - it's extremely unlikely that it's bent), you have to straighten your spiders and/or chain rings. Hold a small screwdriver or other short, pointed object against the seat tube so that the tip just grazes the crank spiders as they pass. If the spiders are bent (most likely problem), you can even them out as follows:
> 
> ...


If the OP takes your advice, I hope he posts a video to YouTube of him trying to straighten the arms on the spider of his CF Vuma Quad crankset!


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## redcorn (Jan 20, 2007)

*I am not touching my cranks like that*

I would never try to straighten out a carbon crank or any crankset that cost 1250 bucks. As long as Zipp is going to warranty it then I am happy.


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## dadoflam (Jan 19, 2008)

Forrest Root said:


> Well considering that BB or frame flex has no demonstrated deleterious effect on performance, chainring flex, I'll bet, has a magnitude or two less effect than those first to things. I'd worry more about aero drag caused by body hair.


You mean there might be an issue after all and I got that full-body wax for nothing!


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## Forrest Root (Dec 22, 2006)

dadoflam said:


> You mean there might be an issue after all and I got that full-body wax for nothing!


No, don't say that. Remember what Confucius said:

_*It is better to look good than to feel good.*_


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## Kerry Irons (Feb 25, 2002)

*Oops*



Forrest Root said:


> If the OP takes your advice, I hope he posts a video to YouTube of him trying to straighten the arms on the spider of his CF Vuma Quad crankset!


Missed the point on the crank arms being CF  At any rate, you can use the procedure I listed as a way to determine if/how much the spider arms are off. It could still just be the chainrings.


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## Forrest Root (Dec 22, 2006)

Kerry Irons said:


> Missed the point on the crank arms being CF  At any rate, you can use the procedure I listed as a way to determine if/how much the spider arms are off. It could still just be the chainrings.


Yeah, yeah, yeah. I got all that, but does that mean that I can't be sub-serious in response?


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## ricker (Mar 25, 2008)

The chainring mating surfaces of the spider are either turned on a lath or machined co-planar on an index/rotating table. It's not likely they are out of co-planarity by much more than a couple of thousanths. 

One thing that comes to mind that might cause deformation would be stresses induced by the carbon arm process,...maybe. It's easily measured though to confirm.

So what's the off-set angle from the big chainring to say the 11,.. a degree or so?

Under load the Vuma chainring looks like it would certainly deflect more than DA.

Also, make sure the pre-load on the bottom bracket bearings is proper to eliminate a lateral displacement issue.


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## Mdeth1313 (Nov 1, 2001)

Forrest Root said:


> No, don't say that. Remember what Confucius said:
> 
> _*It is better to look good than to feel good.*_



Wasnt that billy crystal on SNL in Fernando's Hideaway?


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## redcorn (Jan 20, 2007)

ricker said:


> The chainring mating surfaces of the spider are either turned on a lath or machined co-planar on an index/rotating table. It's not likely they are out of co-planarity by much more than a couple of thousanths.
> 
> One thing that comes to mind that might cause deformation would be stresses induced by the carbon arm process,...maybe. It's easily measured though to confirm.
> 
> ...


Zipp does a good job of engineering a crank that is easy to install. All you do is add the required washers as in the instructions and torque one bolt down to the proper torque. There is no chance of lateral movement from the BB or Arms. 

I finally got my cranks back from Zipp and was kind of disappointed on how they handled the situation. First off the original guy I talked to made it sound like they were just going to give me new cranks since these were two days old when I sent them back to Zipp. However when they got my cranks they said they tested it on their work bench and the results were considered normal with no defects. I dont know what they did to test those cranks but you can see the lateral deviation of the chainrings sid to side when bolted together by just spinnning them on a bike. So after I *****ed and moaned they gave me some new chainrings and sent me back my cranks. First off the new chainrings were definitely stiffer than the original ones but still had the lateral deviations from being bolted onto the spider. I studied the rotations and marked where the rings were being pulled to hard and figured out it was the 4th chainring bolt, the one that bolts right onto the crank arm. I went to the hardware store to look for any washers that were 8mm ID, 13mm OD and 1mm thick. Well that turned into a wild goose chase and I finally found a C clamp retainning clip that was exactly those dimensions. I spent 1 hour sanding layer by layer .2mm thick till the chain rings where true when bolted together. So now I fixed my problem myself thanks alot Zipp! Its a real shame I have to custom mod a 1250 dollar crankset when non of my Shimano, Campy or FSA cranksets had issues out of the box. No more chain rub, no more excessive play in the FD derailling the chain and my chainrings are straight as they should be. 

Overall I love the Zip cranks for the stiffnesss and lightness. As usual I got less than stellar performance from the Zipp staff. :cryin: Live and Learn. If they only knew how much money I have spent on their products. Oh well. Hope I helped someone else out there. This will be my last purchase of Zipp products which are over hyped, over priced and below industry standards for quality.


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## redcorn (Jan 20, 2007)

*Save your money*

Guys save your money don't buy the Zipp Vuma Quads, buy the new FSA BB30 cranksets. They are just as stiff if not stiffer at a cost of 80gms but at least you know their chainrings align right and you can use the extra money on Zero gravity brakes to shave more weight. Not only that but the BB30 standard of FSA and SRAM RED allows internal bearings with standard non proprietory chainrings from all manufacturers. You will save 500 bucks going to FSA. 

http://www.fullspeedahead.com/bb30/

http://www.fullspeedahead.com/bb30/


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## Forrest Root (Dec 22, 2006)

Don't blow your money on BB30 'cuz the odds are that you ain't sufferin' any ill effects from the pittance of BB or BB axle flex you think you're seeing.


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