Left crank arm fell off on yesterday's ride

[Fishbike]

Having a left crank arm hanging from your shoe while still attached to your pedal is a very unsettling sight.

I am spending the long weekend on Nantucket and was riding one of the excellent bike paths. At first I noticed I was having trouble shifting into the big ring and figured I would adjust the cable next time I stopped. A few miles later I thought my left pedal was loose and next thing I notice is the crank arm is scraping the pavement while attached to the shoe. I slowed down and managed to unclip the right shoe but toppled over on my right side. Fortunately I fell on grass and just ended up with some minor scratches and a small bruise on my right hip.

The crank is Rival and needed an 8 mm hex to reattach. I had one on my mini tool but could not get nearly enough leverage to tighten the crank. I called a local bike shop who I persuaded to make a house call and meet me out on the path. The guy came -- begrudgingly -- and attached the crank. $45 later and I was on my way. I was lucky I was just noodling along and had a patch of grass to fall into.

Anyone else ever have crank arm come off? I must admit I said a few naughty works about SRAM.

[Cicli]

That sucks. Unfortunately, it will probably happen again. The interface gets damaged from all the wobboling before it finally fell of. It may not stay tight.

[ajz07]

I have heard of it mostly being a problem with FSA cranks, and indeed it is why I got rid of my Energy crank in favor of a 105. The non-drive side kept coming loose in the middle of rides and it was very close to coming off several times before I would realize, stop, reposition it and tighten all the bolts...so I finally ditched it.

I second the comment above. From what I have read (a least with FSA cranks), once it starts happening it will keep happening. Might try to get a warranty replacement depending on how old the crank is.

[AJosiahK]

1+ above comments

Once it happens it will keep happening. FSA most commonly

Shimano or SRAM over FSA

[shovelhd]

I have an FSA Stages. Never had a single problem. A torque wrench is mandatory.

[mecse]

The crank is Rival and needed an 8 mm hex to reattach. I had one on my mini tool but could not get nearly enough leverage to tighten the crank. I called a local bike shop who I persuaded to make a house call and meet me out on the path. The guy came -- begrudgingly -- and attached the crank. $45 later and I was on my way. I was lucky I was just noodling along and had a patch of grass to fall into.

Anyone else ever have crank arm come off? I must admit I said a few naughty works about SRAM.

I ride a SRAM Rival crank that has managed to stay on, comfortably, for at least 20,000 miles. I've replaced the BB, chainrings

Question: Who did the last crank installation? What about the last takeoff/put on?

[brewsmith]

Hmm, making me rethink my most recent FSA crank purchase....

[oldpotatoe]

ooppsie-not gonna get a warranty, installed poorly(not tight enough) is my guess.

[R3awak3n]

This has happened to me before, I was going slow enough that I just unclaimed the other foot. This was on a Square taper that was not tight enough. It's a awkward feeling to have a crank attached to your pedal lol.

I also have broken a pedal while ridding and it remained attached to the shoe

[Ray]

Never had one fall off, but I had one snap in two during an out of saddle climb. I was lucky there were no cars because it was the left crank that failed and I fell straight over into the travel lane and would have been dead if there was traffic there. It was an old Ritchey crank that was later recalled. It's unsettling at best, potentially fatal at worst. Check your gear at regular intervals to make sure everything is tight and look for the early stages of stress cracks...

-Ray

[tuscanyswe]

I had my left crank arm come off on an ultegra 6800 crank after service. I fell but luckily at a slow speed, crank was still attached to my shoe. Was rather scary even at slow speed.

Same shop also serviced my headset a year later. Then as i ride away and try to steer the only thing moving is the stem and bars. Wheels still pointing straight ahead or at least not as much left as the bars. That was really scary and could have gone really bad had i gained enough speed.

I obv hasn't been using their services since.

[Robbos]

I've seen this happen to two cyclists, and it happened to me once with SRAM GXP cranks. Can validate that there was proper torque spec on two of the three. Solution? Very liberal use of Loctite. Poor design, IMO.

[oldpotatoe]

I've seen this happen to two cyclists, and it happened to me once with SRAM GXP cranks. Can validate that there was proper torque spec on two of the three. Solution? Very liberal use of Loctite. Poor design, IMO.

A lot of these and some FSA weren't tapered spindle meaning it just slid on. Purple loctite, onto dry spindle, as tight as you can make it.

[chiasticon]

yeah I had this happen to a friend with an FSA crank recently. he decided to give cross a shot and me and a couple other friends convinced him that riding your cross bike on the local singletrack is a good way for a roadie to get some handling skills. half a mile into it, his crank arm falls off. he lost the preload adjustment doohicky in the process, but was able to re-attach and finish the ride at least. we all assumed it was the fault of the last person to ride the bike (it had been loaned around to a few people by the previous owner), but it sounds like it may have just been an FSA issue...?

OP: did you use a torque wrench to install your crank arms before this? sram gxp and bb30 are dead simple to install, but a torque wrench is a good idea. this is the first I've heard of one just working its way off, when torqued properly.

[benb]

I had my cranks come apart, but it was an XT Mountain bike setup, and it's one of the older style ones from > 10 years ago where it had the big bolt instead of the new "pinch" design.

Shop guy hadn't tightened it properly. When I took it back to complain about how dangerous it was he tightened it again with a teeny little wrench and I then said something about getting a torque wrench.

Thankfully I have never had a problem with that crankset again.

[bobswire]

Easy fix, pre ride check but I realize some of you depend on shops to do things like torque a bolt,inflate tires,tape handlebars,change a flat. ;)
Well I did have a pedal come off once still attached to my shoe.:o

[fuzzalow]

http://d7ab823tjbf2qywyt3grgq63.wpengine.netdna-cdn.com/wp-content/uploads/readers/Souleur/2011.08.10.01.30.49/fignonmech.jpg

The OP is in good company. This happened to Fignon years ago. The failure was from a break of the bottombracket spindle, Campagnolo titanium Super Record. Which then, as now, has the upgrade from Record to Super Record given pretty much to the added weight savings of titanium, as opposed to steel, bits.

Never experienced a crankset failure of any kind. I do my own wrenching and I trust me.

[benb]

Easy fix, pre ride check but I realize some of you depend on shops to do things like torque a bolt,inflate tires,tape handlebars,change a flat. ;)
Well I did have a pedal come off once still attached to my shoe.:o

You're pretty much right.. in my case I had a tight schedule that week and I had a race & let the shop do some work. My main mistake there was that I had not been out on that bike for a shakedown ride before the race. In my case I did not actually crash when the crank came loose, I was able to stop normally as I detected it loose before it completely fell off. (I think the older design for cranks may have actually been superior in this failure case!) That was right around the time I stopped depending on a shop much. IIRC I had tons and tons of problems with creaking BBs the first 5 years I was cycling and didn't have any BB/Crankset problems. Shortly after that incident I bought a BB/crank tools and torque wrenches and have never had any issues with that part of the bike again. (Other than creaky SRAM chainrings in my 2007-2009 failed SRAM experiment.)

It is fairly bad when you can't depend on shops to do basic stuff like fasten the bike together.. this is a safety issue, and no matter what happens there will always be lots of cyclists who depend on the shop. Some of these incidents surely involve high end/expensive shops too.

[54ny77]

If a ride lasting longer than 4 hours results in your crank falling off, seek medical help immediately.

[distanc3]

Yep, happened to me on the SRAM Rival crank. luckily it was on the flat and not too fast. Replaced the bolt and got rid of it.

[oldpotatoe]

http://d7ab823tjbf2qywyt3grgq63.wpengine.netdna-cdn.com/wp-content/uploads/readers/Souleur/2011.08.10.01.30.49/fignonmech.jpg

The OP is in good company. This happened to Fignon years ago. The failure was from a break of the bottombracket spindle, Campagnolo titanium Super Record. Which then, as now, has the upgrade from Record to Super Record given pretty much to the added weight savings of titanium, as opposed to steel, bits.

Never experienced a crankset failure of any kind. I do my own wrenching and I trust me.

Yup, that generated the v2 solid titanium spindle.