Whats the best course of action for us now then..?
😕

Either get in touch with who you bought in from or try and forget about it and hope they don't break I suppose.

I thought they were hollow forged – which then raises another question – where is the forging split line.

Ive been thinking about this a bit more and i reckon i know what there cracks are. The cranks are made from an extruded tube and i reckon the poster above has got it right, its just the join where the inside surfaces of the tube are squished together, leading to a weaker join in the middle of the crank compared to the solid parent material at the edges. Im (now ive thought about it) pretty sure those cracks wont extend any further than the pictures we have here.

EDIT: The crack cant easilly extend past the end of the join made in the hollow forge process, it would take a significant impact/force to force the crack to extend into the edges of the crack, prob about the same size force that would snap a normal crank! Of course if the crack entend from the end of the crank arm upto the pedal threads then if your pedal works loose it could have the leverage to peel the front part of the crank arm off (though theyd have been screwed anyway as a loose pedal would ruin the threads)

Those with cracks in XT cranks, can you take your pedal off and see if the crack can be seen in the threads?

Good thinking stato.

Thanks for that Stato – makes perfect sense.

I still think youd be within your rights to ask for a replacement if your cranks look as bad as the first pic in this thread tho. No matter what the manufac process is you shouldnt be forced into a situation where you worry about wether a crack is going to get worse and possibly injure you, not matter how unlikely it is.

Hi everyone, Albert from Madison here.

Understandably some of you are concerned about what might appear to be cracks at the tips of your crankarms just below the pedal inserts.

This was brought to Shimano's attention some time ago and upon further investigation they were identified as forging marks (Stato's hit the nail on the head with his explaination). This is why so many of you will have discovered them upon further investigation.

Rest assured these marks do not in any way affect the performance or durability of the cranks/chainsets and to date no cranks have been returned to us with actual cracks at the end of the crank arm.

Thanks
Albert
(Madison)

Oh Gwad… – going to check my XT / XTR cranks very carefully over the weekend…

So, Shimano cranks don't have an inherent design flaw, and it hasn't been discovered on this very website?

😆

how is it a design flaw? surely they are functionally fine then, just show a mark where the tube has been forged together?

I dunno, I can't say I'm too bothered if they're not going to break. I probably would have never thought about it if I hadn't read this thread.

Well thats that cleared up, though I'd have thought it odd to leave the join visible in that manner. Certainly had me baffled as to the stresses that might be causing a crack there!

Has anyone else (Alb?) found their shaft flaking off where it sits in the top hats? Mine is and I'm concerned about it. While its only a surface coating, thats a fairly tight tolerance fit and any gaps will a) let gack down the shaft and b) could cause the shaft to spin in the tophat, wrecking it (if the bearings dont remain perfect).

No-one else had this?

I won't be buying the slx double chainset I had in mind. Maddison – it's a cop out, it's not a quality product, and whats going to happen over time, these cranks haven't exactly been around for long.

Ck, i have that on some oldish lx ht2's so much so that with direct contact bb like hope, there is play within the axle/bearing interface, fine with a shimano bb though, but still clearly visable as a worn groove on the axle..

but, how else would you expect them to make a hollow alluminium crank?

Extrude, then squish together, but you see the mark

Extrude, squish together, wrap in crabon to cover all manufacturing marks? Adding cost and weight?

I reckon Shimano make the best performing cranksets, at a very good price, on the market at the moment.

A small mark (not crack) at the end of the arm due to a manufacturing process is fine by me.

yeah I'm really not bothered about the crack – don't like the sound of the axle wear thing though.

If the crack isn't visible when new and unused then it is a deterioration. I had a look at riding buddies slx after reading this thread, and it was more of a jagged seperation or de-lamination (if you don't want to call it a crack) than a mark!

I check my saint cranks but they're a little battered so no joy there 😳

If the crack isn't visible when new and unused then it is a deterioration

SLX – XT and XTR in the shop all new and unused still in box – all bar XTR showing hte marks ….

my XTs do not …. imho its not an issue.

Old and battered Saints Mk.1 here – no "cracks".
All it means is that in a couple of years' time I'll be changing them to Middleburn, simple.

Coffeeking

Has anyone else found their shaft flaking off

*snigger*

BoardingBob – I should bloody hope not! 😉

Back to the subject in matter – you pays your money you make your choice etc etc.

It ain't good what ever way you dress it up IMO.

have anyones failed yet ? how longs the system been out ? 5 years ? show me a failure caused by these pseudo cracks and i might worry

worry machine at work – some people just want to create problems.

checked my mk1 saints and they have the cracks. you can just about make them out on one side.

the other side they are hidden by the gouges and chips missing where I keep smashing into rocks.

not too concerned….

(1) Strong, (2) light, (3) cheap.. 😉

Has anyone else (Alb?) found their shaft flaking off where it sits in the top hats? Mine is and I'm concerned about it. While its only a surface coating, thats a fairly tight tolerance fit and any gaps will a) let gack down the shaft and b) could cause the shaft to spin in the tophat, wrecking it (if the bearings dont remain perfect).

Yeah I had this problem a while back. My shaft was flaking really badly. Everytime I went to the loo, great big flakes would come off. I think it was because I got gack down my shaft in the first place that caused the problem. Next time I will make sure I wear a tophat before putting my shaft into any other tight fits. 😀

Albert from Madison – are the cranks cold forged? if they are then the inside surfaces of the extrusion may not be bonding properly on the cranks in the photos. As the ends are worked on (pedal thread and shaping of end) after this process any marks/evidence of this would only become visable when the cranks are put into use, appearing as cracks due to movement between the front and back of the crank.

Be interesting to see if anyone with first gen hollowtech (octalink style bb) has found any cracks.

No cracks on my aged Octalink XTs.

Has anyone else (Alb?) found their shaft flaking off where it sits in the top hats?

I have marks on my Hone ones (triples) where they fit the BB but it all seems fine to me though it would be the reason that i replace them (or the one i use with the wife). i also have the marks at the end of th ecranks but am not to worried about it as i can't see how it would lead to any kind of failier of the cranks.

Thanks all,

I think the flaking has come from when the bearings have seized without me realising and the tophats have spun on the shaft. Annoying but doesn't seem to currently affect the performance of my new BB.

worry machine at work – some people just want to create problems.

yup, that's right, no-one had genuine concerns, they were just trying to create problems for no reason, even going to the effort of posting their images on a public forum to get more exposure… 😆

Hi Stato, you're correct in that the HTII crankarms are forged and not cast. This process is pretty complex and Shimano aren't too keen on digressing too much info on how exactly they're made (although information on the patent is readily available for all to see on the internet).

It goes without saying that Shimano are world leaders in drop forged technology and have one of the highest QC levels in the industry. Rest assured the marks on the crankarms do not affect in any way the structural integrity of the crank – they're merely an unsightly byproduct of the manufacturing process.

I agree coffeeking, we're all trouble making bastards, and the importer and shop owner selling the products are of course technically and morally in the right!

Anyone know where I can buy a cracked frame…

I think the flaking has come from when the bearings have seized without me realising and the tophats have spun on the shaft

That was my conclusion too except i know that mine have siezed in the past.

i've got a crack! no flaking on my shaft, though.

if it breaks, i'll get a replacement.

The Madison bloke's explanation sounds entirely plausible to me. It's just a byproduct of how they are made – no different to machining marks on stems or beading on welds.

I had a look at my XTs and one side has a fine line on it, on the other side the end of the crank is sort of not really there any more as it's presumably been grounded against rocks.

Frankly the Shimano cranks are amazing things for the money and am not remotely worried. As for the bloke who reckons he'd be better off on Middleburns 😆 though they do make great chainrings.

It all depends on the original design intent and what the assumptions were when the analysis was done on the design (assuming some structural analysis was carried out).

If the analysis assumed this was a closed volume, then that will give different stress results to an open volume of metal. However, even if this was the case, then seeing as Shimano obviously know of the issue I would assume that any analysis has been re-visited with this in mind. In addition, assuming that the cranks have been physically tested (which I am certain they will have been) and that the test samples are representative of the whole population then this effect will have been considered in this process.

Madison should be applauded for responding to the concerns so quickly and publicly.

On having a 'flaking shaft':

….though it would be the reason that i replace them (or the one i use with the wife)

…the mind boggles (tee hee!) 😆