Snapped Crank

So last night I somehow managed to snap my crank in half while track standing at a red light. I’m just glad it didn’y happen 5 minutes earlier on Yarra Blvd.

I’m only 85kg so I’m guessing they were already cracked but I’ve got a few question and any help would be appreciated

i) I don’t own a crank puller but seeing as how the cranks are rooted already is there any harm in whacking them with a hammer to get them off?

ii) I’m pretty sure I’ve got an old set of cranks in the shed somewhere. What is the best way to work out if these are going to go on without messing up my chainline?

Thanks

What cranks were on there? If they were JIS taper, most road cranks will give you the same chainline with the same BB.

Despite the crank being broken, still use a crank puller. It will make life a lot easier. Trust me, I’ve learnt this lesson the hard way.

Cheers. They are driveline but I’m not sure what taper they are I’ll do some research…

lolwtf, what cranks were they… get a crank puller rip them off, then compare and measure with the shed set?

edit:beaten.

Nothing some duct tape wouldn’t fix.

Seriously though, don’t use a hammer, you could damage other things.

Disturbing how things can catastrophically fail like this.

Yeh, I was thinking as I walked my way home about what would of happened if had occurred a few minutes earllier while I was mashing down a hill.

The bike has never seriously been crashed and Dan installed the cranks for me so I know they were done right.

I’m not sure what I could done differently to prevent this sort of thing. Apart form more regular inspections of everything.

As anyone heard any bad things about drivelines failing?

you’re a lucky guy, obviously that could have been heaps worse. Did you eat tarmac?

The photo by itself tells us next to nothing, but it appears the drive side crank failed completely, at or near the chainring spider (arms), which suggests the possibility of a stress riser creating a crack from poor forging, bad design, or just because. We’d have to see better photos of both broken bits, particularly the break itself which might show discolouration etc from a long term crack which propagated…

more please?

Did it feel wonky before hand? I broke my drive side crank, but it didn’t break off like yours as the minute it cracked I could feel my pedal moving laterally. Probably rode another 5k’s (carefully) with it broken, but it didn’t snap off.

To paraphrase JLN and Kiasu: what cranks were they so we know never to buy from that company ever again?

Was it these?

DRIVELINE Fixie Crankset

I’m putting my money on JIS square taper.

i reckon send the manufacturer some pics of the snapped crank and spider, next to a turd.

The Australian site I saw the cranks on said there was a 12 month warranty on the cranks too…

post up some pics of the fracture faces (with or without a turd) it’d be intersting to see if crackign initated from a manufacturing defect or what.

Looking at them its pretty much how rustychisel described them

Here’s a pic of the crank shear face

They are DRIVELINE brand as JLN posted but there older (~4years but I don’t do huge kms) and only 170mm. There’s no markings giving a model name. They were bought off Dan and up till now they’ve been fine.

I didn’t notice anything until I went to take off and my foot went straight to the floor. Could of been much worse.

The good news is I’ve managed to get the cranks off and the shed ones look like they will match up OK.

Anyone got any tips for getting a pedal off a broken crank w/out a bench vice (I do actually have a vice just no bench)?

Also if any one in need of a biopace chain ring (52 or 40) let me know and they are yours. Or if you want a non-drive side crank you can have that too

Classic fatigue failure. Even without a close up shot you can see the initiation, early crack growth (dark areas radiating out from inside edge of crank), later striations and then final fracture.

Here’s a close up

I guess the question is should they be fatiguing with this sort of usage (~ 30-40kms/week) and how often do you need to inspect to be able to pick up the warning signs of this?

Dude. Fatty.

In all seriousness, things break. I know it sucks - I break things too. The best thing about breaking things, is getting to buy better things.

lol straight out.

I’m 8"

I live near Yarra Blvd. If you’re in the area, I could probably help you out with a crank puller.

You’re 8 inches? I’m not sure that I want more details on that…