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Loose crank arm and squeaky noise
#1
Hey people,

I recently bought an old road bike and the left crank arm has recently started to make a lot of noise and just recently became very loose. It moves freely about an inch and makes riding a bit difficult. I looked around for some help but for some reason my crank doesnt seem to have a crank cap, key hole or anything for me to get the crank off. I've attached some pics to show what I'm working with.

Cheers
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#2
pictures did not come through - and definitely are required.

How old a bike?
What kind of crank (1 piece, 3 piece cottered, 3 piece cotterless, 2 piece, etc)?
Nigel
  Reply
#3
I believe its from the 70s if not older. Not knowledgeable on bikes on the whole. So
http://img.photobucket.com/albums/v422/Rage_Against_Me/IMAG0828.jpg[/IMG]
http://img.photobucket.com/albums/v422/Rage_Against_Me/IMAG0829.jpg

http://img.photobucket.com/albums/v422/Rage_Against_Me/IMAG0830.jpg

http://img.photobucket.com/albums/v422/Rage_Against_Me/IMAG0831.jpg
  Reply
#4
Where are you located? Please add that information to your profile.

Your bike is pre-1980 almost definitely.

You have 3 piece cottered cranks. See: http://sheldonbrown.com/cotters.html

Given your initial description, your BB axle is probably damaged beyond repair.

I would replace your BB and crankset with these:
http://www.amazon.com/Shimano-Crankset-FC-A050-170-Chainguard/dp/B002K2GR76/
http://www.amazon.com/Shimano-Square-Bottom-Bracket-68x113mm/dp/B005DTIKQE/
in the 68x110 size - ASSUMING that your bike is English or Japanese. If it is Italian or French, it will require something different.
Nigel
  Reply
#5
If the bearings are OK, you could just replace the cotter pin. The cotter pins are much softer than the spindle and It's unlikely that being lose would have damaged the spindle. Cotter pins should cost less than a dollar each and a bike shop might fit it for you for a small charge if you don't have tools.

If the bearings are shot, then, as Nigel suggests, I'd consider getting a newer style square taper chainset, or possibly one of the newer types, octalink or ISIS, Hollowtech etc. with a cartridgle style bottom bracket, just make sure you get a compatible crankset and bottom bracket.

However, you will need to check the threading on the bottom bracket shell, as it's an older bike, there's a chance it may be an Italian thread, or possibly something else. Here's some info on BB types/sizes:

http://www.bikeman.com/bicycle-repair-tech-info/bikeman-tech-info/1599-bottom-bracket-types?start=1

http://sheldonbrown.com/bbsize.html

Measure the width of the bottom bracket shell, if it's 68 or 73mm chances are it's an English thread, if it's 70mm, it's likely an Italian thread.
  Reply
#6
Xerxes and I disagree from time to time Smile my personal experience with 3 pcs cottered cranks was the BB axle becoming damaged beyond repair. Possibly because I was young, and lacking knowledge.

From an Engineering perspective, what happens if a cottered crank is ridden for an extended period with it loose is the pounding the cotter pin takes work hardens it to the point where it is about the same hardness as the axle; so continued pounding results in axle damage too.

Based on: "....left crank arm has recently started to make a lot of noise and just recently became very loose..." I strongly suspect that the work hardening was taking place during the noise period.
Nigel
  Reply


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