Have questions or want to discuss cycling? Join Now or Sign In to participate in the BikeRide community.

New: Take Part in the May's Giveaway: Win the LIVALL PikaBoost 2 E-bike Conversion Kit


Crank arm replacement for an idiot
#1
Hi,

I would if anyone could help?
sometime ago, I clipped a kerb with my nearside (to kerb) pedal, resulting in this crank arm falling off.

Since then I have been unable to get the arm to stay on the bike, as I pedal the nut holding the arm in place loosens, the arm begins to wobble and the pedal/arm falls off :-(

I have 3 parts, in the pics attached, crank arm, nut and the hub. what I am missing?

Thanks
Tony
[attachment=1480][attachment=1481][attachment=1482]
  Reply
#2
If you fit the crank arm (without the nut), can you wiggle it off the spindle with your hands?

If so there's your problem:
you've killed the crank arm.
  Reply
#3
i wouldnt say wobble with my hands at all, fits quite nicely really...

in fact this is a new crank arm, I figured the original must be shot after its unexpected meeting with the kerb

Tony
  Reply
#4
If you're tightening the nut down at all firmly and the arm still falls off like that, the crank arm itself is probably damaged. It could be the BB spindle, but since those are steel, they're much harder to damage than the aluminum crank arm. You might try putting your old one back on just for comparison. A curb strike might not have actually done anything beyond cosmetic damage to it. But riding a loose crank arm very far will damage it very quickly.
  Reply
#5
look at the square on the crank arm from the back, if this looks at all bell-mouthed it will need replacing as it will never stay tight again.
It needs to be nutted up very tight the first time it is fitted and never ride with it loose, as this will keep happening.
  Reply
#6
i have the same problem with the second and third picture....i think they're stripped because when i ride it wobbles n falls off.....ive tried wrenching the nut back onto it as tightly as i can but when i ride it goes back to wobbling.....my brother in law[[i think]]said that it was stripped. Im wondering like how to fix it? any answers
  Reply
#7
(10-03-2010, 04:03 AM)Ro-Ro Wrote:  i have the same problem with the second and third picture....i think they're stripped because when i ride it wobbles n falls off.....ive tried wrenching the nut back onto it as tightly as i can but when i ride it goes back to wobbling.....my brother in law[[i think]]said that it was stripped. Im wondering like how to fix it? any answers

See my previous answer, it is rare for the axle itself to be the problem as this is heat treated steel and you can easily see if the axle thread is stripped, but I would always replace the nut as well as the crank arm, note if you buy a new crank arm, make sure the length of the arm and the orientation of the the square is the same as there are 2 types.
  Reply


Possibly Related Threads...

Forum Jump:

[-]
10 Latest Posts
POLL: Are non-recumbent riders looking a...
Yesterday 06:42 PM
Third best reason to ride a bent or trik...
Yesterday 10:13 AM
What was your first bicycle?
Yesterday 04:45 AM
Is anyone riding with music?
Yesterday 04:32 AM
Great Giro
Yesterday 04:18 AM
What are the best pitch black dark night...
Yesterday 01:11 AM
The great thing about trikes
06-05-2025 12:06 PM
Biking with helmet laws
06-04-2025 10:23 AM
"There's been better times
06-03-2025 09:10 PM
Where are you from and What is your favo...
06-02-2025 06:22 PM

[-]
Join BikeRide on Strava
Feel free to join if you are on Strava: www.strava.com/clubs/bikeridecom

[-]
Top 5 Posters This Month
no avatar 1. Criminal
23 posts
no avatar 2. rydabent
18 posts
no avatar 3. Flowrider
17 posts
no avatar 4. GirishH
17 posts
no avatar 5. SPINMAN
12 posts