spacecadetkid

Hey y'all. First post, so here goes. I bought a Nashbar Cyclocross bike and assembled it myself from the box. I, if it's not obvious yet, am a TOTAL NEWBIE when it comes to bicycle mechanics. I have the "Zen and the Art of Road Bike Maintenance book", and I peruse through when I can to learn things.

Today, on the bike ride back home from where I teach, my crank started feeling loose. I didn't have any tools with me or any other way to get back home...7 miles is a long way to walk in clipless shoes, so I just kept pedaling, hoping for the best.

Well, the left crank arm fell completely off. The drive arm is attached still. Is there any way to salvage this crank or do I just have to completely get a new crank/fix the bottom bracket now?

Again, I'm a huge novice at this stuff - so my mistake if I'm making some huge bike mechanic faux pas right now asking these questions.

I just want to be able to commute on my beautiful bike again Please help a brother out!

Mondo734

Am I to understand that you don't have the crank arm that fell off? Because if you still have it and there isn't any damage to the splines on the bb or the crankarm you should just be able to put back on and tighten it up.

spacecadetkid

I definitely still have the crank arm...I just put it in my panier and walked the 3 miles back to my house in my clipless shoes (btw, that sucks).

I don't think anything is honestly damaged at all, I just think it fell apart because I was a dumbass and didn't do anything more than hand-tighten and ghetto-tighten with a torque wrench. It's 100% my fault I believe. I just don't know how to go about re-attaching everything. No pieces are missing I don't think, but I have to go check it out...

corrado33

I agree with above. If nothing looks horribly damaged, you should jsut be able to put it on and crank it down.

BTW, you were wearing clipless shoes, why not just ride home/pedal with one foot? Surely would have been quicker.

spacecadetkid

When the left crank arm came off, the drive-crank kept sliding out and too the right, which sketched me out. I didn't want to keep pedaling like that, especially clipped in to the drive-crank if I fell off for some reason, I wouldn't be able to unclip and would have taken the whole chainring with me haha.

Mondo734

Lol, I take it you have an external bearing setup. In that case I wouldn't have ridden either, having the crankset moving left and right would probably be a bad idea :0

rm -rf

See this Park Tool external bearing crank repair page.

Do you have this style of FSA crankset, with two 5mm bolts that pinch the end of the left crank onto the spindle?


In the photo, the cap that the blue hex wrench is screwing into the spindle is used to tighten the bearings correctly. It doesn't hold the left crank on the spindle, the two 5mm bolts do that. But the cap is critical to adjust before tightening.

You probably lost the cap. (It can actually unscrew without affecting the crank as long as the two bolts keep the crankarm on.) See if your local bike store can order one.

And test fit your crankarm onto the spindle. Are the splines mangled or does the crankarm fit on okay?

Photos would help!

EDIT-- I see that you "assembled it myself from the box". You probably just tightened the cap and then didn't tighten the two bolts correctly. Or maybe the crank was assembled already, and done incorrectly.


You NEED to also redo your stem attachment after reading the Park Tool Repair page for stems. Both the cranks and the stem have the same method of tightening a cap to snug down the bearings--with just a little bit of force! Then securing the stem or the crank with a pair of bolts to hold it in place. The caps can't hold it by themselves.

Both of these aren't very obvious at first, but once you've found out how to assemble them correctly, it then makes sense. A little research up front is a good idea.

spacecadetkid

Let me check this out and I will post photos! Thanks everybody for being so kind to a fellow biker and internet denizen!