Broken crank axle

How old was the spindle/crankset? Have you overhauled it/repacked the bearings regularly?

It looks to me, and it wasn't 100% clear through the pics, that you actucally broke the spindle on the bottom bracket. If that's the case, it should be an easy and realatively cheap fix (you'll need a new BB, but they aren't too pricy).

Good luck.

L

threaded said:

Last night I was going for a "power up" on a slight incline and the crank axle broke. Quite scarey as I was going as fast as possible, as usual. Hurt both knees through sudden stretch and a good thump in the right buttock from crashing onto the seat.

Here are some pictures: threadeds dead bicycle It looks like a classic fatigue fracture to me.

Not cheap parts, all Shimano kit. Bike is used all year round, recently rebuilt rear wheel as 5 spokes were broken. If any of you know Denmark I cycle the length of Roskildevej and back everyday, so the way is a moderately rough cycle path, mostly flat, one hill. Speed is anywhere between 30 and 50 kph, cadence is 70 to 120, usually try to keep to 90.

My questions: What am I doing wrong? Have I just happened to get a "failed" part? What would you recommend as a replacement?

I agree with Lonnie. You need a new BB. That should not be too expensive, $30 USD or less for a basic one.

I had an expert look at it, and it is a fatigue fracture! That's a new claim to fame, "Wore out a crank axle". Who'd have thought it possible?

The front cog would not come off what was left of the crank axle (yes I have the proper tools), it was well hooked anyways, and the arms always felt a little too short, didn't like the pedals either, so that lot got binned. I was finding my cadence topping out in the fastest gear anyways so have gone for a new bottom bracket with sealed bearings, New front is Shimano 105 using a 50 tooth and 175 mm arms, (so now have a left over cog as it is only a single up front), new cassette at the back, a new chain and SPD PD-A520 pedals.

I don't top out on cadence any longer, and consequently cut 6 minutes from my round trip commute first time out, which is now just below 2 hours. And still getting faster as I get used to the new gears of which I find a need for the full range instead of the fastest three previously.

threaded said:

Last night I was going for a "power up" on a slight incline and the crank axle broke. Quite scarey as I was going as fast as possible, as usual. Hurt both knees through sudden stretch and a good thump in the right buttock from crashing onto the seat.

Here are some pictures: threadeds dead bicycle It looks like a classic fatigue fracture to me.

Not cheap parts, all Shimano kit. Bike is used all year round, recently rebuilt rear wheel as 5 spokes were broken. If any of you know Denmark I cycle the length of Roskildevej and back everyday, so the way is a moderately rough cycle path, mostly flat, one hill. Speed is anywhere between 30 and 50 kph, cadence is 70 to 120, usually try to keep to 90.

My questions: What am I doing wrong? Have I just happened to get a "failed" part? What would you recommend as a replacement?

The good news is, that were apparently not out of the saddle, or it could have been your balls and not your butt. Maybe even your face into the top of the bars, if not a bone breaking crash. I don't know of any crankset that has an axel, except the 2007 Campy, and it's not availible yet that I know of. I think you broke your bottom bracket axel/spindle. If the break was vertically in line with the center of the bottom bracket bearings, I would suspect the bearings were the cause or at least a contributing factor, if the bearings shows damage. If not, I would look for a failure, caused by a over tightening of the the crank bolt. Also, is the bottom bracket threaded cup loose? If not, I don't know what is left but axel/spindle fatigue. But at this point, only a metallurgist could tell for sure. As far as a bottom bracket replacement, I have no experience in this area except for what I use. It is from Phil Wood/USA and is considered, pre ceramic, one of the best bottom brackets in the world. It ain't what you pay, but what it costs. This bottom bracket has an unconditional life time warranty, the more miles you put on it, the less it costs per mile. I might add, that Phil originally made his reputation, by making bottom brackets that were needed but not availible. It was for mountain bike riders, before there were mountain bikes and riders were converting beach cruisers to ride in the mountains, mud and salt water surf.

1)defective part
2)counterfeit part

If it is a cone and spindle you could get a new spindle