How often to replace Shimano Hollowtech cranks to avoid catastrophic failure?

Might as well keep my Zee if I’m worried, as it’s non hollow and I have not read a single account of it snapping.

Or just get a non-hollowtech deore! Only 60 grams heavier than the SLX and cheaper

The new FC500 and FC600 are also not hollowtech, but they seem a tad heavier? I can’t find figures anywhere.

Never ever ever seen one snapped before.

Wow, I also never guessed they were ‘that’ hollow.

TBH I’m not phased, I’ve had 3 or 4 sets now on various bikes, SLX is my ‘go to’ Crank.

ive killed two of them, but it’s usually the spline that goes. I ‘think’ it’s caused by over-tightening the Pre-load. But they seem to reach a point when they loose and if I ride them, even for a short time loose they’re goosed.

I’m never sure about the lifespan of aluminium components; I’m fairly sure that my copy of Zinn and the Art … recommends replacing stems and bars every few years

Presumably that hat depends what you’re doing; a weekly bridleway mince isn’t likely to put too much fatigue load on?

Snapped a 105 axle after about 12k miles if that counts? Never done a crank though.

Or just get a non-hollowtech deore! Only 60 grams heavier than the SLX and cheaper

Also a u section, so far more likely to flex and fatigue…….. Probably why they make it heavier.

I replace all my hollowtech cranks every 2 weeks. Dura ace on road bike and xtr on the mtb just to be safe 🙂

I saw the 2 week old cranks in half before binning them so no one else maybe gets hurt !!

yohandsome

Are you saying non hollow tech cranks do not snap ever?

Are you saying non hollow tech cranks do not snap ever?

Seems like Deore non hollow tech and Zee do not snap off ever. I’ve tried to find any mention or photo of one snapped. Guessing they bend before they snap, allegedly deore and zee have the same arm so bending seems unlikely too.

If you google snapped crank arms there are a lot of pictures of sold snapped crank arms.

As far as I can see it’s simply a case of the right tool for the job or there wouldn’t be any point in the heavy duty versions of a crank in any group set.

I googled shimano broken crank.

most of the broken ones I could see were solid.

fwiw, i use slx cranks on my rigid surly, and i weigh 20 stone.

im not that strong, but can still exert (I imagine) a serious amount of leverage on these cranks.

they’ve been on 3 bikes and they haven’t snapped yet.

my experience, (31 years mtb, and have worked in 5 different shops) some people can break anything, but the vast majority actually break nothing.

I remember in about 1990/91, we ordered a pair of campag record cranks in for a tt specialist, he brought his bike in, we fitted them and torqued them up for him and off he went to test them out.

half hour later, he’s back, covered in cuts and grazes, blood all over the place, ‘aw man, those cranks are **** brilliant’

we are like, ‘wtf happened to you?’

apparently, he’d been riding along and looked down to check his pedalling smoothness, and rode straight into a whole family of cyclists. On a Dual Carraigeway. 😳

Found a size 8 black Croc…

Anybody missing one?

I googled shimano broken crank.

most of the broken ones I could see were solid.

I’m counting 10 hollow ones (the seemingly solid one is a hollow 105) and 0 solid crank arms snapped.Still looking for a say post 2010 snapped solid-deore or zee crank arm.

ive killed two of them, but it’s usually the spline that goes. I ‘think’ it’s caused by over-tightening the Pre-load.

Under-tightening the two crank bolts will do this, if they come loose so does the crank wreaking the splines, the pre load does very little beyond helping installation.

Is this the stw version of flat earthers? Evidence of 10 snapped cranks mean a design issue… shimano have only ever sold 100 sets* of cranks that 10% that fail.

*i saw it on a forum post once.

Some people do over think things…

Is today actually 1st April?

I’m counting 10 hollow ones (the seemingly solid one is a hollow 105) and 0 solid crank arms <span class=”skimlinks-unlinked”>snapped.Still</span> looking for a say post 2010 snapped solid-deore or zee crank arm.

What does a search for unsnapped cranks come up with,what about snapped oak trees?

Is this the stw version of flat earthers? Evidence of 10 snapped cranks mean a design issue… shimano have only ever sold 100 sets* of cranks that 10% that fail.

*i saw it on a forum post once.

2 people in this thread reported snapped SLX. That’s 2 out of say 500-2000 people who read the thread. Not insignificant. In 97 shimano had to do a mega recall of cranks that snapped at the pedal I believe.
Also people on trials forums warn against hollowtech so that’s additional anecdotal evidence. Not really an issue though as you can get non hollowtech for less money and only 60 grams more.

I’m taking a week off the forums now..

Only a week.?

Do you work for SRAM/ Campagnolo/ FSA by any chance.?

Wasn’t there some chap about 10 years ago used to collect stories and pics of carbon bikes and components that had snapped? Stuck them all in a blog.

That put a stop to carbon being used in the bicycle industry fo’shure

I’m never sure about the lifespan of aluminium components; I’m fairly sure that my copy of Zinn and the Art … recommends replacing stems and bars every few years but some folk seem to still ride aluminium frames that are decades old (I’m riding a pretty ancient Thomson post too)

I’d love to know also, although it’s possibly better measured in mileage rather than time. I have had a Middleburn crank snap before but it was second hand and then on a commuter so high mileage  (I reckon about 15,000 miles)

The only cranks I have broken were SRAM  / Truvative, that spiral fracture of the spindle thing after 5 years of my 14st battering down trails.

These threads are exactly what I love about Internet forums!  Basically like allowing by of those foil hat wearing American survivalists have access to the internet!

That’s 2 out of say 500-2000 people who read the thread. Not insignificant

Incorrect. Your figures give between 0.4% and 0.1% failure rate. Are you actually saying these cranks are shit when, by your own admission, (admittedly based on made up numbers) 99.9% will be fine?

For something to be considered ‘statistically significant’, by people who know about such things, it has to be above 5%. Anything less is just down to chance. Or insignificant, if you will.

There is a reason that trials riders warn off hollow cranks.

Ever seen the front edge of a trials riders leading crank ?

Equally for failures of solid cranks Google – raceface cranks snapping.

I’m counting 10 hollow ones ……. and 0 solid crank arms <span class=”skimlinks-unlinked”>snapped.</span>

That’s google displaying what you want to see…..

Have you tried more specific searches?

When I searched snapped crank arm, out of the first 21 hits 12 were solid, 8 hollow and 1 I couldnt tell from picture range. It looks like a problms faced by a high stress part to me, not a weakness with HT.

Incorrect. Your figures give between 0.4% and 0.1% failure rate. Are you actually saying these cranks are shit when, by your own admission, (admittedly based on made up numbers) 99.9% will be fine?

For something to be considered ‘statistically significant’, by people who know about such things, it has to be above 5%. Anything less is just down to chance. Or insignificant, if you will.

I’ve been a bike mechanic for 5 years (No that long, sure) and a cyclist for 30, I’ve got lots of mates who cycle too. I’d say thats a decent amount of experience.

I’ve never, ever seen a snapped crank of any type with my own eyes, none, not ever.

I’m not saying it doesn’t happen, obviously it does, but it’s rare. Very very rare.

I’ve seen bent BB axles, mashed pedal threads, bent chainrings, twisted spiders, BBs ground into the frame, inserts in carbon frames trashed (£5k Cervelo if you’re interested) and HT2 LHS cranks with the serrated teeth stripped out (That’s not uncommon). There’s way, way more things to worry about before you get to snapped cranks!

I’ve got some 10 year old XT HT2 which are fine and I bought some used LX (Not SLX) ones which are fine too. But I’m not a crank-arm-rubber like some. I’ve still got the XT logos on my XTs…..

I have a set that are worn by heelrub significantly.  I am sure they are now a lot weaker than when they were made.  I think replacing them at some point would be prudent.

Don’t assume solid arms won’t snap. They’re made of non-bendy aluminium, so won’t just ‘bend’. They’d be rubbish as levers otherwise

For ten years, I’ve only ever used Shimano Hollowtech cranks (SLX and XT).  Reading through this thread, it’s as though I’ve narrowly avoided being killed to death numerous times.

A picture doesn’t tell you much about whether the crank has been mashed into the ground repeatedly, or whether they’ve been subject to accelerated wear thanks to heel rubbage. There are various statutory bodies which will have the authority to force a manufacturer to recall products in event of safety concerns (a quick google brought up this: https://www.evanscycles.com/help/product-recall-notices)

I am troubled that the OP has started another thread with an unsupported assertion in the title.

I managed to snap an xt crank that was over 10 yrs old by rubbing my heels on it over this period, just fell off while I was riding along a canal towpath. I’d been waiting for it to go, I’d rubbed a hole in it a few months before it gave way. Replaced it with deore because that’s what I had lying around in my shed.

Only other crank snapper I’ve known in 30 years riding is my son who in his teens snapped a solid crank on a road bike when he was in a chain gang. I had to drive 40 miles to collect him. This was 20 yrs ago.

Still, most of the things we worry about won’t  happen so maybe the OP isn’t so far wide of the mark

10 years in bike shops, never had any snapped hollowtech cranks in. Doing the maths that means they are 100% reliable and will never break.

I’m counting 10 hollow ones (the seemingly solid one is a hollow 105) and 0 solid crank arms <span class=”skimlinks-unlinked”>snapped.Still</span> looking for a say post 2010 snapped solid-deore or zee crank arm.

Hang on a moment

Snapped axle – solid crank

Bent crank – solid crank

Hollowtech failure

Guy who cut’n’shut them into a 100mm fat bike

road bike (hollowtech failure)

snapped axle

holowtech failure

road bike (hollowtech failure)

axle

axle

Seems like they’re no more likely to fail than any other part of the crank, even if the sample is representative (and it was common enough to be a worry).

<Trump> AND some of those you’ve ticked are cutaway cranks they take to trade shows to show off their hollowness! Not failures, FAKE NEWS </Trump>

Ohh, and at the bottom of  your printscreen we have (drumroll please)

The guy replaced it with SLX.

Hmmmm, Basically 30 years in and out of the workshop. (Thats more depressing than it sounds)

I’ve seen about 30 snapped cranks in that time. Except when i started, state of the art was long and slender, and extremely bendy (relative to todays cranks) Think 7400 D-A and early 80’s Campag Record. They used to actually snap under bigger stronger riders, or those who pedaled like they were riding a weight bench. I’d say most were in that era.

Then you have nothing much of actually snapping through normal use until the latest bonded hollowtech cranks. Where the glue joint fails and the two halves of the crank peel apart. But you can feel those going for a while before they let go.

Seen plenty were idiots have over tightened pinch bolts, or the taper bolts, or screwed the pedal in to over 40Nm, or modified the crank, or gouged it to ferk in a vice.

I’m taking a week off the forums now..

Why? Because people disagree with you?

Never seen this happening in 15 years of using Shimano cranks. As said above, most failure is from over torqued pinch bolts. Seen this happening a few times over the years, so much so that I’ve gave up the plastic preloader and always install alloy ones instead, far more robust from out on the trail over torqueing.

Here are some bike parts which can break during use. You should endeavour to replace each part pictured every few weeks or so to prevent the inevitable catastrophe.