Is this supposed to happen?

[tsarpepe]

I was riding along today when I felt a strange wobble in my right pedal. I dismounted and discovered this:

http://i77.photobucket.com/albums/j79/tsarpepe/Bikes/IMGP1314.jpg

http://i77.photobucket.com/albums/j79/tsarpepe/Bikes/IMGP1313.jpg

[LegendRider]

Is the crank arm drilled out?

[nm87710]

"How can the DA top-quality alloy just tear like that (under minimal strain and with basically no mileage on it)?"

Maybe because it was not designed or engineered to have a milled cut out in the arm

[gemship]

"How can the DA top-quality alloy just tear like that (under minimal strain and with basically no mileage on it)?"

Maybe because it was not designed or engineered to have a milled cut out in the arm :crap: .


yep, now was that really worth the weight savings :confused: Dude you're so lucky you didn't get hurt.

[Pete Serotta]

It should not have done that under any condition. That is the 1st one I ever saw cut out like that with the Dure Ace lettering... Looks like a special run or model.

Shimano in every instance I have heard is very responsive. When I had a wheel problem they corrected it in less than a week (but then my local bike shop is excellent also - so the two of them had me back riding in less than a week.

[tsarpepe]

The crank came on a bike I got on eBay. It was mint. I just assumed that this is the design. It's supposed to be a special anniversary issue of the DA gruppo.

[eddief]

really biz like. And let them know you are concerned about your safety going forward with their products and that you are well connected via the internet with the national and international cycling community. i'd remove the photo immediately.

if you want a full replacement of your crank, or the bike you could have wrecked due to this quality problem...then going public is your ace in the hole, not what you should be doing first.

big company big reputation big quality issue = opportunity for them treating you fairly or much much better...me thinks.

[Pegoready]

Yes, this is Shimano's best crank, broken in TWO places.

You received it broken already with that aftermarket drilling.

[Pete Serotta]

I do not know if it was bought from a dealer or from a private individual, but that has a bearing on warranty.

Being diplomatic and pleasant always works best. Your local LBS may be able to assist you also.

[eddief]

you need to find out. if yes, you are screwed and ought to quit bad mouthing shimano on the world wide web.

[tsarpepe]

Yes, these are the issues:
1) it was bought used
2) I cannot be sure that this was not aftermarket alteration
I also have not seen cranks like that, but as I said, this was supposed to be a "special" edition.

[itspeedmoore]

Something ain't right. I have never seen a dura-ace crank milled out like that. Also, I don't think thats the original chainring, its from the previous generation. I predict you will have a hard time getting anything from Shimano as I don't think that is their problem.

[dave thompson]

I'm going to guess that you will have no recourse with Shimano. That is not a standard crank, it has been obviously modified. 'Special anniversary group'? Someone else's other than Shimano perhaps. I'd be in very close contact with whoever you got the crank from. That is a *very* dangerous modification that could lead to severe injuries.

[shinomaster]

Maybe that was demo/ display crank to show people that it's hollow? Sort of like those cut in half Cannondale frames hanging around in shops.

[tsarpepe]

This is similar: same chainring and same arm, but without the cut out.

http://www.pezcyclingnews.com/photos/tech/scott/Columbia-Dura_Ace.jpg

[shinomaster]

Duraace cranks are not supposed to be cut out that way (the way your crank is.)

[djg]

This is where the powertap comes in handy -- keep it under 2,700 watts and you'll avoid this problem in the future.

[tv_vt]

buy a new one. And chalk it up to experience. Some bozo ruined that crank by cutting that hole in it. Just be glad you didn't get hurt.
Those cranks are not meant to be treated that way.

[nahtnoj]

2) I cannot be sure that this was not aftermarket alteration


Yes, you can. Some douche cut up a $500 crank and sold it to you on eBay as a "special edition".

Now that you know better, I'd be going after the seller. You should have some recourse through eBay or PayPal, especially given the dangerous nature of what you have been sold.

BTW, that is a 55 tooth time trial chain ring.

[tsarpepe]

Yes, you can. Some douche cut up a $500 crank...

Why would anyone do that? To reduce weight?

[ald]

Maybe that was demo/ display crank to show people that it's hollow? Sort of like those cut in half Cannondale frames hanging around in shops.

That is exactly what what that is. Shimano made these cranks as part of a demo display for dealers to show how the cranks are hollow inside. They were never, ever made to used. Somebody with a low iq or low eq (ethical quotient) installed them on a bike. Caveat emptor

[tsarpepe]

BTW, that is a 55 tooth time trial chain ring.

Actually, it's 54.

[tsarpepe]

That is exactly what what that is. Shimano made these cranks as part of a demo display for dealers to show how the cranks are hollow inside. They were never, ever made to used. Somebody with a low iq or low eq (ethical quotient) installed them on a bike. Caveat emptor

Yes, this sounds most plausible. This is most certainly not some "home-made" alteration. The cutout is extremely smooth: clearly, an expert job.

[eddief]

of the manufacturing process that turns out those beauties.

[labratmatt]

That is exactly what what that is. Shimano made these cranks as part of a demo display for dealers to show how the cranks are hollow inside. They were never, ever made to used. Somebody with a low iq or low eq (ethical quotient) installed them on a bike. Caveat emptor

Ding! Ding! Ding! This is a display crank that was given/sold to bike shops to show that the crank arm is hollow.

[Ken Robb]

this should make you wonder about everything else on this bike.

[rugbysecondrow]

this should make you wonder about everything else on this bike.

Agreed. Too bad it happened but glad you are alright.

Hopefully none of these got passed on to anybody else.

Thanks,

Paul

[Dekonick]

Wow. Some sleezeball almost killed you - I would definitely contact fleabay and the seller w/ pics. What ever happened to ethics?

[tsarpepe]

I certainly did! Thanks to everyone who responded. I guess I owe an apology to Shimano, which I am hereby offering. Now, how much was that DA crank? $500? Ouch!

[eddief]

or delete it. can we have a vote?

[pbjbike]

Go back to the seller, and then ebay after, if there is no response. PayPal has buyer protection as well. Not right. Don't take this.

[dannyg1]

I've seen people selling the arms alone, new or in new condition for around $200/set. You can use the chainrings + bolts you've got now. Give us a size and people will keep an eye open for you.

I think that I got a 50% off Shimano sale email from PBK the other day as well.

[tsarpepe]

Well, as it happens, only one of the arms is drilled. The other one is not. So, I guess I just need one.

[spamjoshua]

You got off lucky, as the "ass" that sold you that crank did not actually end up hospitalizing you.

It is scary, and dangerous, and you were lucky.

Hit him for what you can.

Joshua

[toaster]

Quote: 'is this supposed to happen?'

Yes, and it did.

That's why all real Shimano 7800 crankarms do not have cut-outs. This one did and failed spectactularly.

Big ooops!

[Ahneida Ride]

Might I humbly suggest, now that you know the status of this crank arm,
that you go back and edit/manage your original post. :argue:

This way, Shimano does not appear culpable. ;)
I think both Serotta & Shimano would appreciate this correction.

Thanks ....

This is the first post, at least that I can recall, where a major Shimano
component has failed catastrophically. Hmmm, I can' even recall
searching thru my rumor mill recollections, of a Shimano
catastrophic failure event.

Shimano has established a solid reputation with good reason.

[tsarpepe]

Yes, I will certainly alter the post, erasing all negative references to Shimano. But I think no harm will be done if I keep the pictures, as a kind of museum showpiece on the "underworld of road biking."

[BengeBoy]

Reminds me of the golden years of drillium parts:

http://www.velo-retro.com/peterjohnson.html

http://www.tearsforgears.com/2005/09/drillium-info.html

[Ahneida Ride]

Thanks ...

I think this is a lesson here. Use common sense, especially with
every day training components.

If it "Looks" too light, it probably is.

All components should be regularly checked.
and perhaps not by the owner, sometimes one is too familiar with
one's bike and misses stuff.

[Bud_E]

Isn't it stupid for Shimano to make these demo drilled-out-not-meant-to-be-ridden cranks if there's a chance someone will mistakenly ride them and have a catastrophic failure ? It seems sort of reasonable to assume that they are just sexy looking production cranks.

[tsarpepe]

Isn't it stupid for Shimano to make these demo drilled-out-not-meant-to-be-ridden cranks if there's a chance someone will mistakenly ride them and have a catastrophic failure ? It seems sort of reasonable to assume that they are just sexy looking production cranks.

That's exactly what I assumed: that this is some sort of very limited production run. The cutout looked so professional (no sharp edges, perfectly round curves) that it never even occurred to me that it might be a demo. Since decorative drilling on certain bike parts has been done in the past (including crank arms), I didn't for a moment think that it might be unsafe.

[billy58]

Those pics make me shiver!!!!
A crank arm is one component i never want to see daylight through..
Even carbon cranks make me nervous..
I would buy a lottery ticket mate...

[Ahneida Ride]

I'll just bet Shimano never even pondered that these display cranks would
be sold on the open market in a deceptive duplicitous fashion.

Otherwise, they would have installed some form of "Lawyers Lips".

[rustychisel]

preformed cracks or rotating knives at the spindle boss, I wonder?

WWC do?

[RADaines]

Well, as it happens, only one of the arms is drilled. The other one is not. So, I guess I just need one.

Are you saying that the cranks did not match, that one was solid and one was cut out? If so, I would think that would have put up a red flag. Glad you were not hurt.

Maybe it would be worth contacting Shimano to let them know that their display cranks are being sold to unsuspecting buyers? I'm sure that they would appreciate the heads-up.

[ospreybike]

Why would Shimano make a display crank like that, it should have been one that is cut in half or something so they can NEVER be used, Shimano may give you a new crank for letting something like that out to the public. Try to get in touch with someone higher up than the first person you talk to at Shimano.
I am pretty sure they would want that back in their position, legal issues.

[William]

IMO, a display only part should be made non-operable in some way. For example, the cut-out crank could have been made without a pedal hole to prevent something like this from happening. Can't be used if if you can't mount a pedal to it.

Sorry the buyer ended up with this, but I'm happy that you didn't get hurt. Things could have ended up really bad if that happened while you were sprinting or hammering down a decent.





William

EDIT: I didn't see the last response before posting.....obviously we agree. :beer:

[J.Greene]

http://www.atienza.com/wp-content/uploads/2007/10/darwin_awards_hdlg.jpg

[rugbysecondrow]

http://www.atienza.com/wp-content/uploads/2007/10/darwin_awards_hdlg.jpg

This is a little uncalled for.

Most people who ride bikes have better things to do than commit to memory every style of DA crank that may or may not have come off the line. If it looked right, looked professional, then most people would accept this and move on.

I agree that Shimano ought not to have created a crank that was operable at all. Who knows, the bike or an employee from the shop could have sold it like this and passed on the bad info. It should never have been in circulation, IMO.

[John M]

My guess is that part of the appeal of this display model to Shimano is that it could be assembled. It does look cool. They should have engraved on the crank arm back: "display model only--not for actual riding"

[toaster]

What Shimano might have done, IMHO, is to have welded a pedal permanently onto crank and made the weld obvious or welded in an insert that would not accept standard pedal threads.

[gemship]

It's actually pretty easy to make that slot. All you need is some sort of clamp and or fixturing on a bridgeport milling machine. You then set up a tool with a center drill or even just a drill to make a pilot hole for a I don't know what size maybe a 3/8 or 1/2 three fluted end mill. Spin up the end mill a couple grand maybe as fast as 5k rpm's feed the end mill into the pilot hole and then just move the table side to side feeding the crank arm along length wise. The radius, well the finish of the cut looks so nice for the most basic reason as the endmill spinning very fast and the material brought into it's path very slowly. The op noted the nicely rounded ends, well... those ends are naturally formed from the radius of the end mill. This is all very easy to do if one has the proper tools and some very basic understanding. I doubt it saves any notable weight either although that was the first thought of mine was weight savings but display sounds a little more logical.

[RPS]

I doubt it saves any notable weight either although that was the first thought of mine was weight savings but display sounds a little more logical.
Not to me. I have a very hard time visualizing how Shimano would produce display-specific anything that could be installed; particularly when it’s so compromised and dangerous. Disabling would be very simple by either drilling out the pedal threads with a large bit or by cutting off the BBKT axle. If this crank was meant for display to highlight how it is hollow inside, you’d want a person to be able to pick it up in their hands and look at it closely. As a display-specific crank I can not think of any reason there would ever be a need to install it on a bike, or to install a pedal on it. And Shimano knows that.

I could see some machine shop manufacturing a few of these things and selling them to high-volume bike shops for profit, but I just can’t see a company like Shimano doing it themselves without making them inoperable – not unless it was done by a rogue employee in the US without going through the correct channels. And if that’s the case, (s)he should be fired on the spot. That's the main benefit I see in reporting the crank to them -- just in case they have a clueless person on their payroll.

[tsarpepe]

Are you saying that the cranks did not match, that one was solid and one was cut out? If so, I would think that would have put up a red flag. Glad you were not hurt.

Maybe it would be worth contacting Shimano to let them know that their display cranks are being sold to unsuspecting buyers? I'm sure that they would appreciate the heads-up.

No, it's not that the arms didn't match. After all, they were both Dura Ace, with identical lettering. It sort of made sense that the one attached to the flashy TT chainring would also be more flashy. They are, of course, the same length, and came in identical mint condition. The pedals installed easily on both. My first ride was perfectly OK. On the second, however...

[Tobias]

My first ride was perfectly OK. On the second, however...
I'm surprised it lasted that long ..... must have been an easy short ride.

A tubular cross section is very strong and stiff in torsion. When it was cut as in the picture, the top and bottom sections have to resist torque as if they are independent small "C" sections, which would have very little torsional stiffness.

Additionally, the top and bottom segments also have to resist bending as two small cross sections which compounds the stresses at the point of failure. Count yourself lucky you didn't end up on the pavement.

I'm a skeptic by nature and think there has to be more to this than Shimano using poor judgment. Any person with any technical training could look at that crank and see it wasn't meant to be used on a bike. And Shimano engineers are very good.

[Ahneida Ride]

I can easily see how this occurred. We were all newbies at one
time or anther. How is a newbie suppose to discern components?

Hey, I once called up Serotta, got Mr. Bedford and asked some
absurd question like how do I use bartape in my bottom bracket.

Purchasing a new bike, entering the sport, can be intimidating ....
The collective wisdom of this forum should ease this transition.

I can remember the Kahuma days of this forum and how the early
members (many now ATH) graciously entertained all my dumb questions.

:D

[TMB]

It's an "extra feature", really.


OK, maybe not. Glad you were not hurt and I hope you are able to get the seller to deal with the issue - straight up. somehow, I have my doubts on that though.


Ahneida Ride - I have to ask this. What did Bedford say to you in answer to that question???


I've been sitting here laughing at even the thought of the question, I can't imagine being on the other end of the phone .............

[fiamme red]

Hey, I once called up Serotta, got Mr. Bedford and asked some absurd question like how do I use bartape in my bottom bracket.Bottom bracket bra? ;)

[MattTuck]

I can easily see how this occurred. We were all newbies at one
time or anther. How is a newbie suppose to discern components?



Yep.

And on top of that, I see the appeal of saving a few bucks buying used on eBay or even this forum. But at the end of the day, I don't mind paying retail prices to have the peace of mind that the equipment is new and in good shape, and I have someone to go to if something does happen.

[vjp]

I would think that there WAS a "For display only" sticker on the backside of that crank arm at one time.

Have you owned a bike before? Anything else mechanical? Did any bells go off when only one of the arms was milled that way? You have to be at least a little responsible for your own safety and well being.

I am glad that you are OK.

vjp

[veggieburger]

I would try to find out what shop they came from. Is there a serial # anywhere on the crank? If so, Shimano can likely trace its history...once you find out which shop you can make some calls.

[Hai H. Ho]

The crank came on a bike I got on eBay. It was mint. I just assumed that this is the design. It's supposed to be a special anniversary issue of the DA gruppo.

May I ask who the Ebay member is? I'm wondering what sort of Feeback score this seller has? Did this seller present the bike as having a "special annivesary issue of the DA group" or did you assume this as well? I wonder how the seller sourced this one crank arm?

Maybe the seller is not even a bike nut like us and is just a Ebay consignment-type shop. I would love to see the original Ebay ad.

Inquiring minds want to know.

Best of luck with the drama.

P.S. What length arms do you ride? Maybe we here can help you out.

[Hai H. Ho]

Have you owned a bike before? Anything else mechanical? Did any bells go off when only one of the arms was milled that way? You have to be at least a little responsible for your own safety and well being. vjp

Maybe the OP can take pictures of the rest of the bike so that we all can have a glance over to make sure no other bells go off?

I'm in Houston, Texas. Feel free to pm me if you would like for me to glance over the bike in person. I sold and wrenched on bikes for a local bike shop for nearly 4 years during college and would love to help.

[207 cm]

JB weld.

[TMB]

I would think that there WAS a "For display only" sticker on the backside of that crank arm at one time.

Have you owned a bike before? Anything else mechanical? Did any bells go off when only one of the arms was milled that way? You have to be at least a little responsible for your own safety and well being.

I am glad that you are OK.

vjp

Are you doing Whistler????

[tsarpepe]

May I ask who the Ebay member is? I'm wondering what sort of Feeback score this seller has? Did this seller present the bike as having a "special annivesary issue of the DA group" or did you assume this as well? I wonder how the seller sourced this one crank arm?

Maybe the seller is not even a bike nut like us and is just a Ebay consignment-type shop. I would love to see the original Ebay ad.

Inquiring minds want to know.

Best of luck with the drama.

P.S. What length arms do you ride? Maybe we here can help you out.

I myself am an inquiring mind, but the story of this crank is a bit convoluted. I got it together with a 1980s Guerciotti bike on eBay. Here is a picture from the original post. The ill-fated crank is clearly visible:

http://i77.photobucket.com/albums/j79/tsarpepe/Bikes/Guerciotti/Guerciotti1.jpg

I have no reason to believe that the person I got it from is in any way connected with Shimano. Nor did he seem to have been personally involved in putting the bike together (I am basing this assumption on the way he responded to technical questions about the bike). He was a Chinese guy, from LA I think, operating one of those eBay businesses that somehow lay hands on a variety of (unrelated) items, some of them--pretty nice finds. It is probably impossible now to trace how he got his hands on the bike. Especially since I purchased it some six months ago. In any case, I ended up transferring the componennts onto another frame. The newly-assembled bike collected dust for a few months, until I finally took it out of the garage recently. And on the second ride... So, this is the story, folks. If I search through my inbox, I'll probably be able to find the buyer's email. But I am highly sceptical that this would lead to anything. Besides, I am not sure that my inquisitiveness is enough to last me through the kind of recon mission this would require.

[tsarpepe]

The crank is in no way marked as a demo model. Both crank arms bear the standard inscription "Shimano FC-7800". The length is 175. There is no serial number.

[TMB]

That stem is about 180 mm .............

[Lifelover]

Besides, I am not sure that my inquisitiveness is enough to last me through the kind of recon mission this would require.


This one statement proves that you are Wise way beyond what this one series of events might lead some people to believe. I'm a degreed, mechanical Engineer, consider myself to be very mechanically inclined and am pretty familiar with all thinks bike related, I could easily see me buying and riding those cranks with no more than a nagging curiosity as to why only one side was drilled.

Be thankful that you still have your health, replace them with some cheap 105 cranks and ride you bike like you stole it.

[Louis]

with no more than a nagging curiosity as to why only one side was drilled

You mean you would not have calculated the torsional stiffness of the open vs the closed sections to compare the two? ;)

[false_Aest]

Hommé,

Like a bunch of other people, I'm happy you still have your testicles. I'm sorry you learned the hard way.

We all do bone-headed, unenlightened things. The learning curve is steep sometimes; the bling in the bling-bling sometimes blinds us; sometimes you pull the trigger and find out it wasn't a quail you shot but another human.

Count your lucky stars and your lucky testeeeeez. Buy a new crank.
Competitive Cyclist has Ultegra SL cranks for $99 bucks right now. BUY ONE!!!

Does anything more need to be said?

----

HEY! Has anyone seen George Hincapie's new bike. The fit looks wrong.

----

[tsarpepe]

Hommé,
Count your lucky stars and your lucky testeeeeez. Buy a new crank.
Competitive Cyclist has Ultegra SL cranks for $99 bucks right now. BUY ONE!!!

Does anything more need to be said?



Thanks for the tip. One of them cranks is already on its way to me!

[Ahneida Ride]

I'm glad you are alive and healthy my friend !!!! :) :beer:

[RPS]

I'm a degreed, mechanical Engineer, consider myself to be very mechanically inclined and am pretty familiar with all thinks bike related, I could easily see me buying and riding those cranks with no more than a nagging curiosity as to why only one side was drilled.
Who's to say the other side wasn't originally, broke in two, and the owner replaced it so he could sell the bike. :rolleyes:

The lessons I get from this are that we should never alter bike stuff, and that trying to lightweight things to an extreme to save 5 grams on a 20-pound bike is not a good idea. :no:

[tsarpepe]

Who's to say the other side wasn't originally, broke in two, and the owner replaced it so he could sell the bike. :rolleyes:

The lessons I get from this are that we should never alter bike stuff, and that trying to lightweight things to an extreme to save 5 grams on a 20-pound bike is not a good idea. :no:

This is a highly unlikely scenario. The following things have to happen:
1) a DA crank arm breaks (in itself, unbelievable);
2) the guy considers it too much of a trouble or expense to get a new arm;
3) and yet he somehow finds a unique, never-before-seen drilled-out arm of the same model, and same length.

[bshell]

I think he was suggesting the possibility of

a. 2 hole-y cranks
b. breaking one of 'em
c. replacing with a solid one

[RPS]

This is a highly unlikely scenario. The following things have to happen:
1) a DA crank arm breaks (in itself, unbelievable);
2) the guy considers it too much of a trouble or expense to get a new arm;
3) and yet he somehow finds a unique, never-before-seen drilled-out arm of the same model, and same length.
I tried to communicate the very opposite scenario. I was thinking that we don’t really know if the non-drive (i.e. – the left crank) was originally drilled out also along with the drive side crank (as in a matching set of drilled out cranks). If that was the case and it broke in two while the drive-side crank was still OK, the owner may have replaced the non-drive drilled-out crank with a standard crank in order to sell the bike. That’s one of many possible explanations on how you may have gotten the bike with only one crank drilled out.

I did not imply that a standard DA crank would fail. That’s even more unlikely than the scenario I described above.

By the way, one of the most impressive things about the photos you posted is that they show just how good the wall thickness distribution is for the DA hollow cranks. Excellent quality control in my opinion. I like Shimano.

[dlflemingos]

You mean you would not have calculated the torsional stiffness of the open vs the closed sections to compare the two? ;)

Amazing Photo.

If the slot was milled to show the quality of the crank arm it worked because it is amazing quality, lightweight, efficient structure. However it should have been red striped or marked "not for flight". That means modified to preclude use by drilling an oversized hole or cutting off the end. (No hole would allow future use with a mod)

If the slot was intended to save weight, it may have saved 50% of the weight of the modified section and reduced the bending resistance (I) by (wag) 20% at most. But, a bending failure would have been at the max bending section and that is not how it failed.

The section failed in torsion. The pedal force is offset from the crank and also twists the crank arm. The torsion resistance (J) was probably reduced by (wag) 90%. A closed section (tube) is efficient for torsion but the remaining open section is terrible in torsion. The open section has to resist twist with differential bending of the upr and lwr remaining sections and the slot is way too long. Shorter slots (2 or 3?) or just a few holes spaced at 2d might have had a chance but that long slot was a massacre. These parts have obviously been thoroughly optimized and there is no room improvement especially by amateurs.

I'm glad you survived unscathed and passed on this valuable information on. Thanks. You might try JBWeld to fix it because it's stronger than steel.

[tsarpepe]

It's always good to know the physics behind your mishap. Thanks!