Check your cranks?

[davidphilips]

Just watched this on utube, know the cyclist a really nice guy, the crank came of and caused the accident (tightened by a bike shop) he has a broken collar bone.

View: https://www.facebook.com/michael.mckelvey.7/videos/pcb.3078586268852694/3078669815511006/?type=3&theater&ifg=1

 

[DCLane]

If it happens - and it has once to me - you can feel the crank loosening about 30 seconds before it comes off.

 

[silva]

My cases were 1 (bridge up) and 8 (bridge down) sec.
I now swim.

 

[fossyant]

Cranks falling off, what's this ? TBH, it depends on the crank system how easily they might come off'. I can see hollowtech coming off much easier than GXP or Square taper (I've got all three) if things aren't tight.

 

[neil_merseyside]

Looks a nothing 'fall' so very unlucky to get hurt, but 'good' it's only a collar bone as it's quick to heal... BTDTGTTS

 

[Drago]

Thats we religiously do our BESTCOPa pre ride checks.

 

[Milkfloat]

A friend had a groin to top tube coming together after his hollowtech crank came off 25 miles after a new bottom bracket from his LBS. After we finished laughing we had to push him home 15 miles because the splines were totally knackered.

 

[raleighnut]

With any crank I've fitted I have a little test ride (4-5 miles) then check em for tightness, a lot of the time they've 'settled in' and do need a tweak. BTW this has been with every type of crank from cottered to hollowtech, the nicest/best system I've owned is my TT bike with Campagnolo Centaur (10spd) which has a 'Hirth Coupling' in the centre.

 

[Racing roadkill]

It’s part of any sensible ‘M check’. It’s one of the reasons we do it.

 

[Levo-Lon]

I'm of the opinion, if you ride in a group you'll get injured eventually.

Crank coming off while sat? Bit unlucky

 

[MontyVeda]

I'm a bit baffled by this. Didn't the cyclist know they were getting loose?

My cranks used to regularly come loose until I started carrying a long 8mm Allen key... they spent a lot of miles feeling loose rather than just coming off all of a sudden.

 

[Blue Hills]

I'm a bit baffled by this. Didn't the cyclist know they were getting loose?

My cranks used to regularly come loose until I started carrying a long 8mm Allen key... they spent a lot of miles feeling loose rather than just coming off all of a sudden.

Maybe he's one of those cyclists who entrusts his bike to bike shops for services and doesn't do much himself.
I don't actually test ride as such my square taper installs but like you carry a 8mm key around for a while and check and tighten a few times on the first rides. It seems to need tightening at least once at the beginning, then all is fine.
(come to think of maybe he's also the sort who would be horrified at the idea of carrying round a full size 8mm key)

edit - just re-read the initial post more closely - yep, seems he relies on someone else to keep things tight.

Trust he'll recover - might be an idea to peruse the Park Book with a cup of tea while he's laid up.

 

[mjr]

I'm of the opinion, if you ride in a group you'll get injured eventually.

Crank coming off while sat? Bit unlucky

What's being in a group got to do with it? Steel cranks pulled off by magnetic attraction of steel parts on other nearby bikes?

 

[presta]

I've never had a crank come off, but I had one break:

My mother's partner gave me his bike to repair a puncture once, it had about 30 degrees of free play on the crank. He'd ridden it loose until the axle had chewed a lump out of the cotter pin, so that when he tightened it the nut just ran up against the end of the thread. From the vacant look I got when I replaced it, the improvement was lost on him.

I'm a bit baffled by this. Didn't the cyclist know they were getting loose?

My cranks used to regularly come loose until I started carrying a long 8mm Allen key... they spent a lot of miles feeling loose rather than just coming off all of a sudden.

It probably depends on whether or not the bolt falls out before the crank works loose on the taper. I went into the LBS to buy a crank tool once, the guy just gave me a blank look and said "What do you want that for, we just take the bolt out and jump on the pedals until the crank comes off".

 

[MontyVeda]

...
It probably depends on whether or not the bolt falls out before the crank works loose on the taper. I went into the LBS to buy a crank tool once, the guy just gave me a blank look and said "What do you want that for, we just take the bolt out and jump on the pedals until the crank comes off".

In my experience, the crank works loose on the spline/taper as soon as it's got somewhere to go. i.e. the bolt is slightly loose. I can't see how the bolt can work itself out all the way without the rider noticing a bit of wobble on the crank.

I've advised folk on here many a time to do similar to what your LBS does if they don't have a crank tool... loosen the bolt, ride round the block and the crank will come loose in no time.